Add Blockstate and Model data providers (#6241)

build.gradle

@@ -159,7 +159,10 @@ project(':forge') {
                 ]
             }
             resources {
-                srcDirs = ["$rootDir/src/test/resources"]
+                srcDirs = [
+                    "$rootDir/src/test/resources",
+                    "$rootDir/src/generated_test/resources"
+                ]
             }
         }
         userdev {
@@ -308,7 +311,8 @@ project(':forge') {
                 source sourceSets.main
                 source sourceSets.userdev
                 
-                args '--mod', 'forge', '--all', '--output', rootProject.file('src/generated/resources/')
+                args '--mod', 'forge', '--all', '--output', rootProject.file('src/generated/resources/'), '--validate',
+                        '--existing', sourceSets.main.resources.srcDirs[0]
             }
 
             forge_test_data {
@@ -321,7 +325,8 @@ project(':forge') {
                     tests { sources  sourceSets.test }
                 }
                 
-                args '--mod', 'data_gen_test', '--all', '--output', rootProject.file('src/generated_test/resources/')
+                args '--mod', 'data_gen_test', '--all', '--output', rootProject.file('src/generated_test/resources/'), '--validate',
+                        '--existing', sourceSets.main.resources.srcDirs[0]
             }
         }
     }

patches/minecraft/net/minecraft/data/Main.java.patch

@@ -7,10 +7,11 @@
  import java.io.IOException;
  import java.nio.file.Path;
  import java.nio.file.Paths;
-@@ -21,8 +22,10 @@
+@@ -21,8 +22,11 @@
        OptionSpec<Void> optionspec6 = optionparser.accepts("all", "Include all generators");
        OptionSpec<String> optionspec7 = optionparser.accepts("output", "Output folder").withRequiredArg().defaultsTo("generated");
        OptionSpec<String> optionspec8 = optionparser.accepts("input", "Input folder").withRequiredArg();
++      OptionSpec<String> existing = optionparser.accepts("existing", "Existing resource packs that generated resources can reference").withRequiredArg();
 +      OptionSpec<File> gameDir = optionparser.accepts("gameDir").withRequiredArg().ofType(File.class).defaultsTo(new File(".")).required();
 +      OptionSpec<String> mod = optionparser.accepts("mod", "A modid to dump").withRequiredArg().withValuesSeparatedBy(",");
        OptionSet optionset = optionparser.parse(p_main_0_);
@@ -19,7 +20,7 @@
           Path path = Paths.get(optionspec7.value(optionset));
           boolean flag = optionset.has(optionspec6);
           boolean flag1 = flag || optionset.has(optionspec2);
-@@ -30,10 +33,11 @@
+@@ -30,10 +34,12 @@
           boolean flag3 = flag || optionset.has(optionspec3);
           boolean flag4 = flag || optionset.has(optionspec4);
           boolean flag5 = flag || optionset.has(optionspec5);
@@ -28,8 +29,9 @@
 -         }).collect(Collectors.toList()), flag1, flag2, flag3, flag4, flag5);
 -         datagenerator.func_200392_c();
 +         Collection<Path> inputs = optionset.valuesOf(optionspec8).stream().map(Paths::get).collect(Collectors.toList());
++         Collection<Path> existingPacks = optionset.valuesOf(existing).stream().map(Paths::get).collect(Collectors.toList());
 +         java.util.Set<String> mods = new java.util.HashSet<>(optionset.valuesOf(mod));
-+         net.minecraftforge.fml.ModLoader.get().runDataGenerator(mods, path, inputs, flag2, flag1, flag3, flag4, flag5);
++         net.minecraftforge.fml.ModLoader.get().runDataGenerator(mods, path, inputs, existingPacks, flag2, flag1, flag3, flag4, flag5);
 +         if (mods.contains("minecraft") || mods.isEmpty())
 +            func_200264_a(mods.isEmpty() ? path : path.resolve("minecraft"), inputs, flag1, flag2, flag3, flag4, flag5).func_200392_c();
        } else {

src/generated_test/resources/.cache/cache

@@ -1,2 +1,64 @@
+dc2deb0c2da07695855bbb88882455a80787ccac assets\data_gen_test\models\block\acacia_door_bottom.json
+e987df4921fc71322984556e9617915d4df2bdff assets\data_gen_test\models\block\acacia_door_bottom_hinge.json
+5103910559b21ce74f315358935a3e582b0c45cd assets\data_gen_test\models\block\acacia_door_top.json
+590e2cc0ba335ffc618441d6fcc582401ee646cc assets\data_gen_test\models\block\acacia_door_top_hinge.json
+9c4e371aace89c681b4ea367975f9b4569acaada assets\data_gen_test\models\block\acacia_fence_gate.json
+1e2e4ace5adef04a3cee3d528c33382a18f40513 assets\data_gen_test\models\block\acacia_fence_gate_open.json
+557312487766c0801958d72d13b0ac16d8d5d9fd assets\data_gen_test\models\block\acacia_fence_gate_wall.json
+dd8d2e76831b2a445737f378458db5c505a9b03d assets\data_gen_test\models\block\acacia_fence_gate_wall_open.json
+4d5b8be3e004e34e75c0f7d415595e14f8985d6c assets\data_gen_test\models\block\acacia_fence_post.json
+90491fcfa42ee4d8ec7958655866f5a3b55811ad assets\data_gen_test\models\block\acacia_fence_side.json
+9bf079dec64b632446a867744149d0fccff6fc70 assets\data_gen_test\models\block\acacia_log.json
+462367a50d9ab2306ca642a72b5fd20c217dc451 assets\data_gen_test\models\block\acacia_slab.json
+3032bec1f17684ceef914e3763b9be773d17b02f assets\data_gen_test\models\block\acacia_slab_top.json
+3611756373823dced8f5db5237a6ee0a5f3cbb7a assets\data_gen_test\models\block\acacia_stairs.json
+72a7c67a73c6217ad117d5583a329e89fd34f246 assets\data_gen_test\models\block\acacia_stairs_inner.json
+34f85d11d44a198433f530bd54c2c172d7699872 assets\data_gen_test\models\block\acacia_stairs_outer.json
+31c3b7793cb61870bd74e8e85af7597be57827c6 assets\data_gen_test\models\block\acacia_trapdoor_bottom.json
+8be9644fe5227cb2c3af52af01b02e9c2c4f9a38 assets\data_gen_test\models\block\acacia_trapdoor_open.json
+8978e4a1d2902029738eac82749ffc2c30088fe9 assets\data_gen_test\models\block\acacia_trapdoor_top.json
+88c7bca952fda50e5287ddb5c2e74ff179d08eb2 assets\data_gen_test\models\block\barrel.json
+ce5d10ee7ab7afed216f3159bdcd5b1deb114104 assets\data_gen_test\models\block\barrel_open.json
+c3ecb601615c300cafbdd9dc28f9fc42b6835dcd assets\data_gen_test\models\block\birch_fence_gate.json
+3bcea12fba8714c7ad7c00f440f3e7546a8958ce assets\data_gen_test\models\block\birch_fence_gate_open.json
+13b47687fb80334b3e51781e691f53f8073843a7 assets\data_gen_test\models\block\birch_fence_gate_wall.json
+dd0a89461e5f72c08ccf6f3d07bce9c290019022 assets\data_gen_test\models\block\birch_fence_gate_wall_open.json
+1d0f4dceda264528ae1b1f5f971ae84202405e51 assets\data_gen_test\models\block\block.json
+42fcd2c027f204708f423808f22f6e4c0d5f586b assets\data_gen_test\models\block\cobblestone_wall_post.json
+21d8ec1410152c67c4b7a06184be545ef1e1d0cf assets\data_gen_test\models\block\cobblestone_wall_side.json
+26c80ee9a99336b434c9984445bfcf01b25f2cd0 assets\data_gen_test\models\block\cube.json
+428f68585535789c809eb40d8151a5baa2b0045b assets\data_gen_test\models\block\furnace.json
+51a161348cf0c51252dbdbad035b7945e02a8763 assets\data_gen_test\models\block\furnace_on.json
+eb911d39c848d09bc5910aef1a86af63b4fbb6c6 assets\data_gen_test\models\block\glass_pane_noside.json
+e5df8cc0b7dd9f79fe930711bcf8e60385b8b7ab assets\data_gen_test\models\block\glass_pane_noside_alt.json
+b178beb42e1db7d177ceb28f0703876943c22a90 assets\data_gen_test\models\block\glass_pane_post.json
+17cd1168c6c32e1fbd870a9e61716aed6ba7c8a2 assets\data_gen_test\models\block\glass_pane_side.json
+85326250de254ad1bba0ad183c78e876afa3da51 assets\data_gen_test\models\block\glass_pane_side_alt.json
+cebd38234491e0882901230538b4205bcf816597 assets\data_gen_test\models\block\oak_trapdoor_bottom.json
+d8842f8f1a63ee4ac0bcc52e83a375de983b8bb0 assets\data_gen_test\models\block\oak_trapdoor_open.json
+091f1cf54c828d8c8315cedeb28a3f864a72456e assets\data_gen_test\models\block\oak_trapdoor_top.json
+a5ace137c931b71acf2599184832187a241acc9c assets\data_gen_test\models\block\stone.json
+78f9176f15f3a728ee20b5a734e89a32c8108395 assets\data_gen_test\models\block\torch.json
+e1820400e7b8e4011121eae3f7c873d73f301cd7 assets\data_gen_test\models\block\wall_torch.json
+d96ff395b92ed2419c8c4aa6e61a610ef78b3216 assets\data_gen_test\models\item\fishing_rod.json
+abe69efd05a6349acca7e39f3353d7c928a55a72 assets\data_gen_test\models\item\fishing_rod_cast.json
+e1a3a09af48181e868c26741053e36eafe8bead6 assets\data_gen_test\models\item\test_block_model.json
+9a27e0d9a3f3d2a834eff92661e090eeda1c59fe assets\data_gen_test\models\item\test_generated_model.json
+1767c874758bd7c3235db446b6219e6e1edd25b4 assets\minecraft\blockstates\acacia_door.json
+e41383b4c13ec922c0f5cfa2cc313d88fd294685 assets\minecraft\blockstates\acacia_fence.json
+967d268bfcf32474b61578bef16e853b6360dd73 assets\minecraft\blockstates\acacia_fence_gate.json
+e9af65f877e6d012bce27ae35eef3822dda98675 assets\minecraft\blockstates\acacia_log.json
+2fc1c2cff82aaebdb4ecf298e6de278c62cce3b3 assets\minecraft\blockstates\acacia_slab.json
+075938fd82340c895eff226d11898abae9a5e178 assets\minecraft\blockstates\acacia_stairs.json
+9384d458574395650a976b3ad1fe5905b100ddbf assets\minecraft\blockstates\acacia_trapdoor.json
+42a10a132337264c8821426e17d0c09b92ad42f9 assets\minecraft\blockstates\barrel.json
+9bc8ba4b8e4ad3cc7074838cf1bf8dad89e2b339 assets\minecraft\blockstates\birch_fence_gate.json
+acbf9f921b05785d49d8526870ba13aee1a322f7 assets\minecraft\blockstates\cobblestone_wall.json
+6a3c8e2691b6b7f39f1236a17bb6aa145a9db53f assets\minecraft\blockstates\furnace.json
+1b2a1344020237ab877e27c43934b042d259bf36 assets\minecraft\blockstates\glass_pane.json
+bf2e445b48b024354a69138b20a4a4a8aa5d15d1 assets\minecraft\blockstates\oak_trapdoor.json
+9c4cc92efb78811e8d70a383a1a89eb75b69db04 assets\minecraft\blockstates\stone.json
+570fdd86046df75a073b759ff7aaf4c4caf43115 assets\minecraft\blockstates\torch.json
+16f12628d0c23a4ca66961b0a1c837c3b1e4457d assets\minecraft\blockstates\wall_torch.json
 4fbaf6f4a3ea05cc071076e27f44ac81f9cc50e3 data\data_gen_test\advancements\conditional.json
 ed4cbf1a3a2f5d8969f6346fdc9acdbe81d0c919 data\data_gen_test\recipes\conditional.json

src/generated_test/resources/assets/data_gen_test/models/block/acacia_door_bottom.json

@@ -0,0 +1,7 @@
+{
+  "parent": "block/door_bottom",
+  "textures": {
+    "bottom": "block/acacia_door_bottom",
+    "top": "block/acacia_door_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_door_bottom_hinge.json

@@ -0,0 +1,7 @@
+{
+  "parent": "block/door_bottom_rh",
+  "textures": {
+    "bottom": "block/acacia_door_bottom",
+    "top": "block/acacia_door_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_door_top.json

@@ -0,0 +1,7 @@
+{
+  "parent": "block/door_top",
+  "textures": {
+    "bottom": "block/acacia_door_bottom",
+    "top": "block/acacia_door_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_door_top_hinge.json

@@ -0,0 +1,7 @@
+{
+  "parent": "block/door_top_rh",
+  "textures": {
+    "bottom": "block/acacia_door_bottom",
+    "top": "block/acacia_door_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_fence_gate.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_fence_gate",
+  "textures": {
+    "texture": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_fence_gate_open.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_fence_gate_open",
+  "textures": {
+    "texture": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_fence_gate_wall.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_fence_gate_wall",
+  "textures": {
+    "texture": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_fence_gate_wall_open.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_fence_gate_wall_open",
+  "textures": {
+    "texture": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_fence_post.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/fence_post",
+  "textures": {
+    "texture": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_fence_side.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/fence_side",
+  "textures": {
+    "texture": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_log.json

@@ -0,0 +1,7 @@
+{
+  "parent": "block/cube_column",
+  "textures": {
+    "side": "block/acacia_log",
+    "end": "block/acacia_log_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_slab.json

@@ -0,0 +1,8 @@
+{
+  "parent": "block/slab",
+  "textures": {
+    "side": "block/acacia_planks",
+    "bottom": "block/acacia_planks",
+    "top": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_slab_top.json

@@ -0,0 +1,8 @@
+{
+  "parent": "block/slab_top",
+  "textures": {
+    "side": "block/acacia_planks",
+    "bottom": "block/acacia_planks",
+    "top": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_stairs.json

@@ -0,0 +1,8 @@
+{
+  "parent": "block/stairs",
+  "textures": {
+    "side": "block/acacia_planks",
+    "bottom": "block/acacia_planks",
+    "top": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_stairs_inner.json

@@ -0,0 +1,8 @@
+{
+  "parent": "block/inner_stairs",
+  "textures": {
+    "side": "block/acacia_planks",
+    "bottom": "block/acacia_planks",
+    "top": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_stairs_outer.json

@@ -0,0 +1,8 @@
+{
+  "parent": "block/outer_stairs",
+  "textures": {
+    "side": "block/acacia_planks",
+    "bottom": "block/acacia_planks",
+    "top": "block/acacia_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_trapdoor_bottom.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_orientable_trapdoor_bottom",
+  "textures": {
+    "texture": "block/acacia_trapdoor"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_trapdoor_open.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_orientable_trapdoor_open",
+  "textures": {
+    "texture": "block/acacia_trapdoor"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/acacia_trapdoor_top.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_orientable_trapdoor_top",
+  "textures": {
+    "texture": "block/acacia_trapdoor"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/barrel.json

@@ -0,0 +1,8 @@
+{
+  "parent": "block/cube_bottom_top",
+  "textures": {
+    "side": "block/barrel_side",
+    "bottom": "block/barrel_bottom",
+    "top": "block/barrel_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/barrel_open.json

@@ -0,0 +1,8 @@
+{
+  "parent": "block/cube_bottom_top",
+  "textures": {
+    "side": "block/barrel_side",
+    "bottom": "block/barrel_bottom",
+    "top": "block/barrel_top_open"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/birch_fence_gate.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_fence_gate",
+  "textures": {
+    "texture": "block/birch_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/birch_fence_gate_open.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_fence_gate_open",
+  "textures": {
+    "texture": "block/birch_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/birch_fence_gate_wall.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_fence_gate_wall",
+  "textures": {
+    "texture": "block/birch_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/birch_fence_gate_wall_open.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_fence_gate_wall_open",
+  "textures": {
+    "texture": "block/birch_planks"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/block.json

@@ -0,0 +1,76 @@
+{
+  "display": {
+    "gui": {
+      "rotation": [
+        30,
+        225,
+        0
+      ],
+      "scale": [
+        0.625,
+        0.625,
+        0.625
+      ]
+    },
+    "ground": {
+      "translation": [
+        0,
+        3,
+        0
+      ],
+      "scale": [
+        0.25,
+        0.25,
+        0.25
+      ]
+    },
+    "fixed": {
+      "scale": [
+        0.5,
+        0.5,
+        0.5
+      ]
+    },
+    "thirdperson_righthand": {
+      "rotation": [
+        75,
+        45,
+        0
+      ],
+      "translation": [
+        0,
+        2.5,
+        0
+      ],
+      "scale": [
+        0.375,
+        0.375,
+        0.375
+      ]
+    },
+    "firstperson_righthand": {
+      "rotation": [
+        0,
+        45,
+        0
+      ],
+      "scale": [
+        0.4,
+        0.4,
+        0.4
+      ]
+    },
+    "firstperson_lefthand": {
+      "rotation": [
+        0,
+        225,
+        0
+      ],
+      "scale": [
+        0.4,
+        0.4,
+        0.4
+      ]
+    }
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/cobblestone_wall_post.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_wall_post",
+  "textures": {
+    "wall": "block/cobblestone"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/cobblestone_wall_side.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_wall_side",
+  "textures": {
+    "wall": "block/cobblestone"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/cube.json

@@ -0,0 +1,43 @@
+{
+  "parent": "data_gen_test:block/block",
+  "elements": [
+    {
+      "from": [
+        0,
+        0,
+        0
+      ],
+      "to": [
+        16,
+        16,
+        16
+      ],
+      "faces": {
+        "down": {
+          "texture": "#down",
+          "cullface": "down"
+        },
+        "up": {
+          "texture": "#up",
+          "cullface": "up"
+        },
+        "north": {
+          "texture": "#north",
+          "cullface": "north"
+        },
+        "south": {
+          "texture": "#south",
+          "cullface": "south"
+        },
+        "west": {
+          "texture": "#west",
+          "cullface": "west"
+        },
+        "east": {
+          "texture": "#east",
+          "cullface": "east"
+        }
+      }
+    }
+  ]
+}

src/generated_test/resources/assets/data_gen_test/models/block/furnace.json

@@ -0,0 +1,8 @@
+{
+  "parent": "block/orientable",
+  "textures": {
+    "side": "block/furnace_side",
+    "front": "block/furnace_front",
+    "top": "block/furnace_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/furnace_on.json

@@ -0,0 +1,8 @@
+{
+  "parent": "block/orientable",
+  "textures": {
+    "side": "block/furnace_side",
+    "front": "block/furnace_front_on",
+    "top": "block/furnace_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/glass_pane_noside.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_glass_pane_noside",
+  "textures": {
+    "pane": "block/glass"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/glass_pane_noside_alt.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_glass_pane_noside_alt",
+  "textures": {
+    "pane": "block/glass"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/glass_pane_post.json

@@ -0,0 +1,7 @@
+{
+  "parent": "block/template_glass_pane_post",
+  "textures": {
+    "pane": "block/glass",
+    "edge": "block/glass_pane_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/glass_pane_side.json

@@ -0,0 +1,7 @@
+{
+  "parent": "block/template_glass_pane_side",
+  "textures": {
+    "pane": "block/glass",
+    "edge": "block/glass_pane_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/glass_pane_side_alt.json

@@ -0,0 +1,7 @@
+{
+  "parent": "block/template_glass_pane_side_alt",
+  "textures": {
+    "pane": "block/glass",
+    "edge": "block/glass_pane_top"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/oak_trapdoor_bottom.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_trapdoor_bottom",
+  "textures": {
+    "texture": "block/oak_trapdoor"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/oak_trapdoor_open.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_trapdoor_open",
+  "textures": {
+    "texture": "block/oak_trapdoor"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/oak_trapdoor_top.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_trapdoor_top",
+  "textures": {
+    "texture": "block/oak_trapdoor"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/stone.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/cube_all",
+  "textures": {
+    "all": "block/stone"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/torch.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/template_torch",
+  "textures": {
+    "torch": "block/torch"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/block/wall_torch.json

@@ -0,0 +1,6 @@
+{
+  "parent": "block/torch_wall",
+  "textures": {
+    "torch": "block/torch"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/item/fishing_rod.json

@@ -0,0 +1,14 @@
+{
+  "parent": "item/handheld_rod",
+  "textures": {
+    "layer0": "item/fishing_rod"
+  },
+  "overrides": [
+    {
+      "predicate": {
+        "cast": 1.0
+      },
+      "model": "item/fishing_rod_cast"
+    }
+  ]
+}

src/generated_test/resources/assets/data_gen_test/models/item/fishing_rod_cast.json

@@ -0,0 +1,6 @@
+{
+  "parent": "data_gen_test:item/fishing_rod",
+  "textures": {
+    "layer0": "item/fishing_rod_cast"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/item/test_block_model.json

@@ -0,0 +1,48 @@
+{
+  "parent": "block/block",
+  "textures": {
+    "all": "block/dirt",
+    "top": "block/stone"
+  },
+  "elements": [
+    {
+      "from": [
+        0,
+        0,
+        0
+      ],
+      "to": [
+        16,
+        16,
+        16
+      ],
+      "faces": {
+        "down": {
+          "texture": "#all",
+          "cullface": "down"
+        },
+        "up": {
+          "texture": "#top",
+          "cullface": "up",
+          "tintindex": 0
+        },
+        "north": {
+          "texture": "#all",
+          "cullface": "north"
+        },
+        "south": {
+          "texture": "#all",
+          "cullface": "south"
+        },
+        "west": {
+          "texture": "#all",
+          "cullface": "west"
+        },
+        "east": {
+          "texture": "#all",
+          "cullface": "east"
+        }
+      }
+    }
+  ]
+}

src/generated_test/resources/assets/data_gen_test/models/item/test_generated_model.json

@@ -0,0 +1,6 @@
+{
+  "parent": "item/generated",
+  "textures": {
+    "layer0": "block/stone"
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/acacia_door.json

@@ -0,0 +1,124 @@
+{
+  "variants": {
+    "facing=north,half=upper,hinge=left,open=false": {
+      "model": "data_gen_test:block/acacia_door_top",
+      "y": 270
+    },
+    "facing=south,half=upper,hinge=left,open=false": {
+      "model": "data_gen_test:block/acacia_door_top",
+      "y": 90
+    },
+    "facing=west,half=upper,hinge=left,open=false": {
+      "model": "data_gen_test:block/acacia_door_top",
+      "y": 180
+    },
+    "facing=east,half=upper,hinge=left,open=false": {
+      "model": "data_gen_test:block/acacia_door_top"
+    },
+    "facing=north,half=lower,hinge=left,open=false": {
+      "model": "data_gen_test:block/acacia_door_bottom",
+      "y": 270
+    },
+    "facing=south,half=lower,hinge=left,open=false": {
+      "model": "data_gen_test:block/acacia_door_bottom",
+      "y": 90
+    },
+    "facing=west,half=lower,hinge=left,open=false": {
+      "model": "data_gen_test:block/acacia_door_bottom",
+      "y": 180
+    },
+    "facing=east,half=lower,hinge=left,open=false": {
+      "model": "data_gen_test:block/acacia_door_bottom"
+    },
+    "facing=north,half=upper,hinge=right,open=false": {
+      "model": "data_gen_test:block/acacia_door_top_hinge",
+      "y": 270
+    },
+    "facing=south,half=upper,hinge=right,open=false": {
+      "model": "data_gen_test:block/acacia_door_top_hinge",
+      "y": 90
+    },
+    "facing=west,half=upper,hinge=right,open=false": {
+      "model": "data_gen_test:block/acacia_door_top_hinge",
+      "y": 180
+    },
+    "facing=east,half=upper,hinge=right,open=false": {
+      "model": "data_gen_test:block/acacia_door_top_hinge"
+    },
+    "facing=north,half=lower,hinge=right,open=false": {
+      "model": "data_gen_test:block/acacia_door_bottom_hinge",
+      "y": 270
+    },
+    "facing=south,half=lower,hinge=right,open=false": {
+      "model": "data_gen_test:block/acacia_door_bottom_hinge",
+      "y": 90
+    },
+    "facing=west,half=lower,hinge=right,open=false": {
+      "model": "data_gen_test:block/acacia_door_bottom_hinge",
+      "y": 180
+    },
+    "facing=east,half=lower,hinge=right,open=false": {
+      "model": "data_gen_test:block/acacia_door_bottom_hinge"
+    },
+    "facing=north,half=upper,hinge=left,open=true": {
+      "model": "data_gen_test:block/acacia_door_top_hinge"
+    },
+    "facing=south,half=upper,hinge=left,open=true": {
+      "model": "data_gen_test:block/acacia_door_top_hinge",
+      "y": 180
+    },
+    "facing=west,half=upper,hinge=left,open=true": {
+      "model": "data_gen_test:block/acacia_door_top_hinge",
+      "y": 270
+    },
+    "facing=east,half=upper,hinge=left,open=true": {
+      "model": "data_gen_test:block/acacia_door_top_hinge",
+      "y": 90
+    },
+    "facing=north,half=lower,hinge=left,open=true": {
+      "model": "data_gen_test:block/acacia_door_bottom_hinge"
+    },
+    "facing=south,half=lower,hinge=left,open=true": {
+      "model": "data_gen_test:block/acacia_door_bottom_hinge",
+      "y": 180
+    },
+    "facing=west,half=lower,hinge=left,open=true": {
+      "model": "data_gen_test:block/acacia_door_bottom_hinge",
+      "y": 270
+    },
+    "facing=east,half=lower,hinge=left,open=true": {
+      "model": "data_gen_test:block/acacia_door_bottom_hinge",
+      "y": 90
+    },
+    "facing=north,half=upper,hinge=right,open=true": {
+      "model": "data_gen_test:block/acacia_door_top",
+      "y": 180
+    },
+    "facing=south,half=upper,hinge=right,open=true": {
+      "model": "data_gen_test:block/acacia_door_top"
+    },
+    "facing=west,half=upper,hinge=right,open=true": {
+      "model": "data_gen_test:block/acacia_door_top",
+      "y": 90
+    },
+    "facing=east,half=upper,hinge=right,open=true": {
+      "model": "data_gen_test:block/acacia_door_top",
+      "y": 270
+    },
+    "facing=north,half=lower,hinge=right,open=true": {
+      "model": "data_gen_test:block/acacia_door_bottom",
+      "y": 180
+    },
+    "facing=south,half=lower,hinge=right,open=true": {
+      "model": "data_gen_test:block/acacia_door_bottom"
+    },
+    "facing=west,half=lower,hinge=right,open=true": {
+      "model": "data_gen_test:block/acacia_door_bottom",
+      "y": 90
+    },
+    "facing=east,half=lower,hinge=right,open=true": {
+      "model": "data_gen_test:block/acacia_door_bottom",
+      "y": 270
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/acacia_fence.json

@@ -0,0 +1,48 @@
+{
+  "multipart": [
+    {
+      "apply": {
+        "model": "data_gen_test:block/acacia_fence_post"
+      }
+    },
+    {
+      "when": {
+        "north": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/acacia_fence_side",
+        "uvlock": true
+      }
+    },
+    {
+      "when": {
+        "south": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/acacia_fence_side",
+        "y": 180,
+        "uvlock": true
+      }
+    },
+    {
+      "when": {
+        "west": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/acacia_fence_side",
+        "y": 270,
+        "uvlock": true
+      }
+    },
+    {
+      "when": {
+        "east": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/acacia_fence_side",
+        "y": 90,
+        "uvlock": true
+      }
+    }
+  ]
+}

src/generated_test/resources/assets/minecraft/blockstates/acacia_fence_gate.json

@@ -0,0 +1,80 @@
+{
+  "variants": {
+    "facing=north,in_wall=false,open=false": {
+      "model": "data_gen_test:block/acacia_fence_gate",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=south,in_wall=false,open=false": {
+      "model": "data_gen_test:block/acacia_fence_gate",
+      "uvlock": true
+    },
+    "facing=west,in_wall=false,open=false": {
+      "model": "data_gen_test:block/acacia_fence_gate",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=east,in_wall=false,open=false": {
+      "model": "data_gen_test:block/acacia_fence_gate",
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=north,in_wall=true,open=false": {
+      "model": "data_gen_test:block/acacia_fence_gate_wall",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=south,in_wall=true,open=false": {
+      "model": "data_gen_test:block/acacia_fence_gate_wall",
+      "uvlock": true
+    },
+    "facing=west,in_wall=true,open=false": {
+      "model": "data_gen_test:block/acacia_fence_gate_wall",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=east,in_wall=true,open=false": {
+      "model": "data_gen_test:block/acacia_fence_gate_wall",
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=north,in_wall=false,open=true": {
+      "model": "data_gen_test:block/acacia_fence_gate_open",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=south,in_wall=false,open=true": {
+      "model": "data_gen_test:block/acacia_fence_gate_open",
+      "uvlock": true
+    },
+    "facing=west,in_wall=false,open=true": {
+      "model": "data_gen_test:block/acacia_fence_gate_open",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=east,in_wall=false,open=true": {
+      "model": "data_gen_test:block/acacia_fence_gate_open",
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=north,in_wall=true,open=true": {
+      "model": "data_gen_test:block/acacia_fence_gate_wall_open",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=south,in_wall=true,open=true": {
+      "model": "data_gen_test:block/acacia_fence_gate_wall_open",
+      "uvlock": true
+    },
+    "facing=west,in_wall=true,open=true": {
+      "model": "data_gen_test:block/acacia_fence_gate_wall_open",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=east,in_wall=true,open=true": {
+      "model": "data_gen_test:block/acacia_fence_gate_wall_open",
+      "y": 270,
+      "uvlock": true
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/acacia_log.json

@@ -0,0 +1,16 @@
+{
+  "variants": {
+    "axis=x": {
+      "model": "data_gen_test:block/acacia_log",
+      "x": 90,
+      "y": 90
+    },
+    "axis=y": {
+      "model": "data_gen_test:block/acacia_log"
+    },
+    "axis=z": {
+      "model": "data_gen_test:block/acacia_log",
+      "x": 90
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/acacia_slab.json

@@ -0,0 +1,13 @@
+{
+  "variants": {
+    "type=top": {
+      "model": "data_gen_test:block/acacia_slab_top"
+    },
+    "type=bottom": {
+      "model": "data_gen_test:block/acacia_slab"
+    },
+    "type=double": {
+      "model": "minecraft:block/acacia_planks"
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/acacia_stairs.json

@@ -0,0 +1,209 @@
+{
+  "variants": {
+    "facing=north,half=top,shape=straight": {
+      "model": "data_gen_test:block/acacia_stairs",
+      "x": 180,
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=south,half=top,shape=straight": {
+      "model": "data_gen_test:block/acacia_stairs",
+      "x": 180,
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=west,half=top,shape=straight": {
+      "model": "data_gen_test:block/acacia_stairs",
+      "x": 180,
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=east,half=top,shape=straight": {
+      "model": "data_gen_test:block/acacia_stairs",
+      "x": 180,
+      "uvlock": true
+    },
+    "facing=north,half=bottom,shape=straight": {
+      "model": "data_gen_test:block/acacia_stairs",
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=south,half=bottom,shape=straight": {
+      "model": "data_gen_test:block/acacia_stairs",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=west,half=bottom,shape=straight": {
+      "model": "data_gen_test:block/acacia_stairs",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=east,half=bottom,shape=straight": {
+      "model": "data_gen_test:block/acacia_stairs"
+    },
+    "facing=north,half=top,shape=inner_left": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "x": 180,
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=south,half=top,shape=inner_left": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "x": 180,
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=west,half=top,shape=inner_left": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "x": 180,
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=east,half=top,shape=inner_left": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "x": 180,
+      "uvlock": true
+    },
+    "facing=north,half=bottom,shape=inner_left": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=south,half=bottom,shape=inner_left": {
+      "model": "data_gen_test:block/acacia_stairs_inner"
+    },
+    "facing=west,half=bottom,shape=inner_left": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=east,half=bottom,shape=inner_left": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=north,half=top,shape=inner_right": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "x": 180,
+      "uvlock": true
+    },
+    "facing=south,half=top,shape=inner_right": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "x": 180,
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=west,half=top,shape=inner_right": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "x": 180,
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=east,half=top,shape=inner_right": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "x": 180,
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=north,half=bottom,shape=inner_right": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=south,half=bottom,shape=inner_right": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=west,half=bottom,shape=inner_right": {
+      "model": "data_gen_test:block/acacia_stairs_inner",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=east,half=bottom,shape=inner_right": {
+      "model": "data_gen_test:block/acacia_stairs_inner"
+    },
+    "facing=north,half=top,shape=outer_left": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "x": 180,
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=south,half=top,shape=outer_left": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "x": 180,
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=west,half=top,shape=outer_left": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "x": 180,
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=east,half=top,shape=outer_left": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "x": 180,
+      "uvlock": true
+    },
+    "facing=north,half=bottom,shape=outer_left": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=south,half=bottom,shape=outer_left": {
+      "model": "data_gen_test:block/acacia_stairs_outer"
+    },
+    "facing=west,half=bottom,shape=outer_left": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=east,half=bottom,shape=outer_left": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=north,half=top,shape=outer_right": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "x": 180,
+      "uvlock": true
+    },
+    "facing=south,half=top,shape=outer_right": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "x": 180,
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=west,half=top,shape=outer_right": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "x": 180,
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=east,half=top,shape=outer_right": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "x": 180,
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=north,half=bottom,shape=outer_right": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=south,half=bottom,shape=outer_right": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=west,half=bottom,shape=outer_right": {
+      "model": "data_gen_test:block/acacia_stairs_outer",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=east,half=bottom,shape=outer_right": {
+      "model": "data_gen_test:block/acacia_stairs_outer"
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/acacia_trapdoor.json

@@ -0,0 +1,68 @@
+{
+  "variants": {
+    "facing=north,half=top,open=false": {
+      "model": "data_gen_test:block/acacia_trapdoor_top"
+    },
+    "facing=south,half=top,open=false": {
+      "model": "data_gen_test:block/acacia_trapdoor_top",
+      "y": 180
+    },
+    "facing=west,half=top,open=false": {
+      "model": "data_gen_test:block/acacia_trapdoor_top",
+      "y": 270
+    },
+    "facing=east,half=top,open=false": {
+      "model": "data_gen_test:block/acacia_trapdoor_top",
+      "y": 90
+    },
+    "facing=north,half=bottom,open=false": {
+      "model": "data_gen_test:block/acacia_trapdoor_bottom"
+    },
+    "facing=south,half=bottom,open=false": {
+      "model": "data_gen_test:block/acacia_trapdoor_bottom",
+      "y": 180
+    },
+    "facing=west,half=bottom,open=false": {
+      "model": "data_gen_test:block/acacia_trapdoor_bottom",
+      "y": 270
+    },
+    "facing=east,half=bottom,open=false": {
+      "model": "data_gen_test:block/acacia_trapdoor_bottom",
+      "y": 90
+    },
+    "facing=north,half=top,open=true": {
+      "model": "data_gen_test:block/acacia_trapdoor_open",
+      "x": 180,
+      "y": 180
+    },
+    "facing=south,half=top,open=true": {
+      "model": "data_gen_test:block/acacia_trapdoor_open",
+      "x": 180
+    },
+    "facing=west,half=top,open=true": {
+      "model": "data_gen_test:block/acacia_trapdoor_open",
+      "x": 180,
+      "y": 90
+    },
+    "facing=east,half=top,open=true": {
+      "model": "data_gen_test:block/acacia_trapdoor_open",
+      "x": 180,
+      "y": 270
+    },
+    "facing=north,half=bottom,open=true": {
+      "model": "data_gen_test:block/acacia_trapdoor_open"
+    },
+    "facing=south,half=bottom,open=true": {
+      "model": "data_gen_test:block/acacia_trapdoor_open",
+      "y": 180
+    },
+    "facing=west,half=bottom,open=true": {
+      "model": "data_gen_test:block/acacia_trapdoor_open",
+      "y": 270
+    },
+    "facing=east,half=bottom,open=true": {
+      "model": "data_gen_test:block/acacia_trapdoor_open",
+      "y": 90
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/barrel.json

@@ -0,0 +1,56 @@
+{
+  "variants": {
+    "facing=down,open=false": {
+      "model": "data_gen_test:block/barrel",
+      "x": 180
+    },
+    "facing=up,open=false": {
+      "model": "data_gen_test:block/barrel"
+    },
+    "facing=north,open=false": {
+      "model": "data_gen_test:block/barrel",
+      "x": 90
+    },
+    "facing=south,open=false": {
+      "model": "data_gen_test:block/barrel",
+      "x": 90,
+      "y": 180
+    },
+    "facing=west,open=false": {
+      "model": "data_gen_test:block/barrel",
+      "x": 90,
+      "y": 270
+    },
+    "facing=east,open=false": {
+      "model": "data_gen_test:block/barrel",
+      "x": 90,
+      "y": 90
+    },
+    "facing=down,open=true": {
+      "model": "data_gen_test:block/barrel_open",
+      "x": 180
+    },
+    "facing=up,open=true": {
+      "model": "data_gen_test:block/barrel_open"
+    },
+    "facing=north,open=true": {
+      "model": "data_gen_test:block/barrel_open",
+      "x": 90
+    },
+    "facing=south,open=true": {
+      "model": "data_gen_test:block/barrel_open",
+      "x": 90,
+      "y": 180
+    },
+    "facing=west,open=true": {
+      "model": "data_gen_test:block/barrel_open",
+      "x": 90,
+      "y": 270
+    },
+    "facing=east,open=true": {
+      "model": "data_gen_test:block/barrel_open",
+      "x": 90,
+      "y": 90
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/birch_fence_gate.json

@@ -0,0 +1,104 @@
+{
+  "variants": {
+    "facing=north,in_wall=false,open=false": [
+      {
+        "model": "minecraft:builtin/generated"
+      },
+      {
+        "model": "data_gen_test:block/birch_fence_gate",
+        "y": 180,
+        "uvlock": true,
+        "weight": 100
+      }
+    ],
+    "facing=south,in_wall=false,open=false": [
+      {
+        "model": "minecraft:builtin/generated"
+      },
+      {
+        "model": "data_gen_test:block/birch_fence_gate",
+        "uvlock": true,
+        "weight": 100
+      }
+    ],
+    "facing=west,in_wall=false,open=false": [
+      {
+        "model": "minecraft:builtin/generated"
+      },
+      {
+        "model": "data_gen_test:block/birch_fence_gate",
+        "y": 90,
+        "uvlock": true,
+        "weight": 100
+      }
+    ],
+    "facing=east,in_wall=false,open=false": [
+      {
+        "model": "minecraft:builtin/generated"
+      },
+      {
+        "model": "data_gen_test:block/birch_fence_gate",
+        "y": 270,
+        "uvlock": true,
+        "weight": 100
+      }
+    ],
+    "facing=north,in_wall=true,open=false": {
+      "model": "data_gen_test:block/birch_fence_gate_wall",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=south,in_wall=true,open=false": {
+      "model": "data_gen_test:block/birch_fence_gate_wall",
+      "uvlock": true
+    },
+    "facing=west,in_wall=true,open=false": {
+      "model": "data_gen_test:block/birch_fence_gate_wall",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=east,in_wall=true,open=false": {
+      "model": "data_gen_test:block/birch_fence_gate_wall",
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=north,in_wall=false,open=true": {
+      "model": "data_gen_test:block/birch_fence_gate_open",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=south,in_wall=false,open=true": {
+      "model": "data_gen_test:block/birch_fence_gate_open",
+      "uvlock": true
+    },
+    "facing=west,in_wall=false,open=true": {
+      "model": "data_gen_test:block/birch_fence_gate_open",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=east,in_wall=false,open=true": {
+      "model": "data_gen_test:block/birch_fence_gate_open",
+      "y": 270,
+      "uvlock": true
+    },
+    "facing=north,in_wall=true,open=true": {
+      "model": "data_gen_test:block/birch_fence_gate_wall_open",
+      "y": 180,
+      "uvlock": true
+    },
+    "facing=south,in_wall=true,open=true": {
+      "model": "data_gen_test:block/birch_fence_gate_wall_open",
+      "uvlock": true
+    },
+    "facing=west,in_wall=true,open=true": {
+      "model": "data_gen_test:block/birch_fence_gate_wall_open",
+      "y": 90,
+      "uvlock": true
+    },
+    "facing=east,in_wall=true,open=true": {
+      "model": "data_gen_test:block/birch_fence_gate_wall_open",
+      "y": 270,
+      "uvlock": true
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/cobblestone_wall.json

@@ -0,0 +1,51 @@
+{
+  "multipart": [
+    {
+      "when": {
+        "up": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/cobblestone_wall_post"
+      }
+    },
+    {
+      "when": {
+        "north": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/cobblestone_wall_side",
+        "uvlock": true
+      }
+    },
+    {
+      "when": {
+        "south": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/cobblestone_wall_side",
+        "y": 180,
+        "uvlock": true
+      }
+    },
+    {
+      "when": {
+        "west": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/cobblestone_wall_side",
+        "y": 270,
+        "uvlock": true
+      }
+    },
+    {
+      "when": {
+        "east": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/cobblestone_wall_side",
+        "y": 90,
+        "uvlock": true
+      }
+    }
+  ]
+}

src/generated_test/resources/assets/minecraft/blockstates/furnace.json

@@ -0,0 +1,34 @@
+{
+  "variants": {
+    "facing=north,lit=false": {
+      "model": "data_gen_test:block/furnace"
+    },
+    "facing=south,lit=false": {
+      "model": "data_gen_test:block/furnace",
+      "y": 180
+    },
+    "facing=west,lit=false": {
+      "model": "data_gen_test:block/furnace",
+      "y": 270
+    },
+    "facing=east,lit=false": {
+      "model": "data_gen_test:block/furnace",
+      "y": 90
+    },
+    "facing=north,lit=true": {
+      "model": "data_gen_test:block/furnace_on"
+    },
+    "facing=south,lit=true": {
+      "model": "data_gen_test:block/furnace_on",
+      "y": 180
+    },
+    "facing=west,lit=true": {
+      "model": "data_gen_test:block/furnace_on",
+      "y": 270
+    },
+    "facing=east,lit=true": {
+      "model": "data_gen_test:block/furnace_on",
+      "y": 90
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/glass_pane.json

@@ -0,0 +1,77 @@
+{
+  "multipart": [
+    {
+      "apply": {
+        "model": "data_gen_test:block/glass_pane_post"
+      }
+    },
+    {
+      "when": {
+        "north": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/glass_pane_side"
+      }
+    },
+    {
+      "when": {
+        "north": "false"
+      },
+      "apply": {
+        "model": "data_gen_test:block/glass_pane_noside"
+      }
+    },
+    {
+      "when": {
+        "south": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/glass_pane_side_alt"
+      }
+    },
+    {
+      "when": {
+        "south": "false"
+      },
+      "apply": {
+        "model": "data_gen_test:block/glass_pane_noside_alt",
+        "y": 90
+      }
+    },
+    {
+      "when": {
+        "west": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/glass_pane_side_alt",
+        "y": 90
+      }
+    },
+    {
+      "when": {
+        "west": "false"
+      },
+      "apply": {
+        "model": "data_gen_test:block/glass_pane_noside",
+        "y": 270
+      }
+    },
+    {
+      "when": {
+        "east": "true"
+      },
+      "apply": {
+        "model": "data_gen_test:block/glass_pane_side",
+        "y": 90
+      }
+    },
+    {
+      "when": {
+        "east": "false"
+      },
+      "apply": {
+        "model": "data_gen_test:block/glass_pane_noside_alt"
+      }
+    }
+  ]
+}

src/generated_test/resources/assets/minecraft/blockstates/oak_trapdoor.json

@@ -0,0 +1,58 @@
+{
+  "variants": {
+    "facing=north,half=top,open=false": {
+      "model": "data_gen_test:block/oak_trapdoor_top"
+    },
+    "facing=south,half=top,open=false": {
+      "model": "data_gen_test:block/oak_trapdoor_top"
+    },
+    "facing=west,half=top,open=false": {
+      "model": "data_gen_test:block/oak_trapdoor_top"
+    },
+    "facing=east,half=top,open=false": {
+      "model": "data_gen_test:block/oak_trapdoor_top"
+    },
+    "facing=north,half=bottom,open=false": {
+      "model": "data_gen_test:block/oak_trapdoor_bottom"
+    },
+    "facing=south,half=bottom,open=false": {
+      "model": "data_gen_test:block/oak_trapdoor_bottom"
+    },
+    "facing=west,half=bottom,open=false": {
+      "model": "data_gen_test:block/oak_trapdoor_bottom"
+    },
+    "facing=east,half=bottom,open=false": {
+      "model": "data_gen_test:block/oak_trapdoor_bottom"
+    },
+    "facing=north,half=top,open=true": {
+      "model": "data_gen_test:block/oak_trapdoor_open"
+    },
+    "facing=south,half=top,open=true": {
+      "model": "data_gen_test:block/oak_trapdoor_open",
+      "y": 180
+    },
+    "facing=west,half=top,open=true": {
+      "model": "data_gen_test:block/oak_trapdoor_open",
+      "y": 270
+    },
+    "facing=east,half=top,open=true": {
+      "model": "data_gen_test:block/oak_trapdoor_open",
+      "y": 90
+    },
+    "facing=north,half=bottom,open=true": {
+      "model": "data_gen_test:block/oak_trapdoor_open"
+    },
+    "facing=south,half=bottom,open=true": {
+      "model": "data_gen_test:block/oak_trapdoor_open",
+      "y": 180
+    },
+    "facing=west,half=bottom,open=true": {
+      "model": "data_gen_test:block/oak_trapdoor_open",
+      "y": 270
+    },
+    "facing=east,half=bottom,open=true": {
+      "model": "data_gen_test:block/oak_trapdoor_open",
+      "y": 90
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/stone.json

@@ -0,0 +1,40 @@
+{
+  "variants": {
+    "": [
+      {
+        "model": "data_gen_test:block/stone"
+      },
+      {
+        "model": "data_gen_test:block/stone",
+        "y": 90
+      },
+      {
+        "model": "data_gen_test:block/stone",
+        "y": 180
+      },
+      {
+        "model": "data_gen_test:block/stone",
+        "y": 270
+      },
+      {
+        "model": "data_gen_test:block/stone",
+        "x": 180
+      },
+      {
+        "model": "data_gen_test:block/stone",
+        "x": 180,
+        "y": 90
+      },
+      {
+        "model": "data_gen_test:block/stone",
+        "x": 180,
+        "y": 180
+      },
+      {
+        "model": "data_gen_test:block/stone",
+        "x": 180,
+        "y": 270
+      }
+    ]
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/torch.json

@@ -0,0 +1,7 @@
+{
+  "variants": {
+    "": {
+      "model": "data_gen_test:block/torch"
+    }
+  }
+}

src/generated_test/resources/assets/minecraft/blockstates/wall_torch.json

@@ -0,0 +1,20 @@
+{
+  "variants": {
+    "facing=north": {
+      "model": "data_gen_test:block/wall_torch",
+      "y": 270
+    },
+    "facing=south": {
+      "model": "data_gen_test:block/wall_torch",
+      "y": 90
+    },
+    "facing=west": {
+      "model": "data_gen_test:block/wall_torch",
+      "y": 180
+    },
+    "facing=east": {
+      "model": "data_gen_test:block/wall_torch",
+      "y": 360
+    }
+  }
+}

src/main/java/net/minecraftforge/client/model/generators/BlockModelBuilder.java

@@ -0,0 +1,37 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2019.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.client.model.generators;
+
+import net.minecraft.util.ResourceLocation;
+
+/**
+ * Builder for block models, does not currently provide any additional
+ * functionality over {@link ModelBuilder}, purely a stub class with a concrete
+ * generic.
+ * 
+ * @see ModelProvider
+ * @see ModelBuilder
+ */
+public class BlockModelBuilder extends ModelBuilder<BlockModelBuilder> {
+
+    public BlockModelBuilder(ResourceLocation outputLocation, ExistingFileHelper existingFileHelper) {
+        super(outputLocation, existingFileHelper);
+    }
+}

src/main/java/net/minecraftforge/client/model/generators/BlockModelProvider.java

@@ -0,0 +1,14 @@
+package net.minecraftforge.client.model.generators;
+
+import net.minecraft.data.DataGenerator;
+
+/**
+ * Stub class to extend for block model data providers, eliminates some
+ * boilerplate constructor parameters.
+ */
+public abstract class BlockModelProvider extends ModelProvider<BlockModelBuilder> {
+
+    public BlockModelProvider(DataGenerator generator, String modid, ExistingFileHelper existingFileHelper) {
+        super(generator, modid, BLOCK_FOLDER, BlockModelBuilder::new, existingFileHelper);
+    }
+}

src/main/java/net/minecraftforge/client/model/generators/BlockStateProvider.java

@@ -0,0 +1,546 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2019.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.client.model.generators;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+
+import javax.annotation.Nonnull;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+
+import net.minecraft.block.Block;
+import net.minecraft.block.BlockState;
+import net.minecraft.block.DoorBlock;
+import net.minecraft.block.FenceBlock;
+import net.minecraft.block.FenceGateBlock;
+import net.minecraft.block.FourWayBlock;
+import net.minecraft.block.LogBlock;
+import net.minecraft.block.PaneBlock;
+import net.minecraft.block.RotatedPillarBlock;
+import net.minecraft.block.SixWayBlock;
+import net.minecraft.block.SlabBlock;
+import net.minecraft.block.StairsBlock;
+import net.minecraft.block.TrapDoorBlock;
+import net.minecraft.block.WallBlock;
+import net.minecraft.data.DataGenerator;
+import net.minecraft.data.IDataProvider;
+import net.minecraft.state.properties.AttachFace;
+import net.minecraft.state.properties.BlockStateProperties;
+import net.minecraft.state.properties.DoorHingeSide;
+import net.minecraft.state.properties.DoubleBlockHalf;
+import net.minecraft.state.properties.Half;
+import net.minecraft.state.properties.SlabType;
+import net.minecraft.state.properties.StairsShape;
+import net.minecraft.util.Direction;
+import net.minecraft.util.Direction.Axis;
+import net.minecraft.util.ResourceLocation;
+
+/**
+ * Data provider for blockstate files. Extends {@link BlockModelProvider} so that
+ * blockstates and their referenced models can be provided in tandem.
+ */
+public abstract class BlockStateProvider extends BlockModelProvider {
+
+    private static final Logger LOGGER = LogManager.getLogger();
+    private static final Gson GSON = (new GsonBuilder()).setPrettyPrinting().disableHtmlEscaping().create();
+
+    @VisibleForTesting
+    protected final Map<Block, IGeneratedBlockstate> registeredBlocks = new LinkedHashMap<>();
+
+    public BlockStateProvider(DataGenerator gen, String modid, ExistingFileHelper exFileHelper) {
+        super(gen, modid, exFileHelper);
+    }
+
+    @Override
+    protected final void registerModels() {
+        registeredBlocks.clear();
+        registerStatesAndModels();
+        for (Map.Entry<Block, IGeneratedBlockstate> entry : registeredBlocks.entrySet()) {
+            saveBlockState(entry.getValue().toJson(), entry.getKey());
+        }
+    }
+
+    protected abstract void registerStatesAndModels();
+
+    protected VariantBlockStateBuilder getVariantBuilder(Block b) {
+        if (registeredBlocks.containsKey(b)) {
+            IGeneratedBlockstate old = registeredBlocks.get(b);
+            Preconditions.checkState(old instanceof VariantBlockStateBuilder);
+            return (VariantBlockStateBuilder) old;
+        } else {
+            VariantBlockStateBuilder ret = new VariantBlockStateBuilder(b);
+            registeredBlocks.put(b, ret);
+            return ret;
+        }
+    }
+
+    protected MultiPartBlockStateBuilder getMultipartBuilder(Block b) {
+        if (registeredBlocks.containsKey(b)) {
+            IGeneratedBlockstate old = registeredBlocks.get(b);
+            Preconditions.checkState(old instanceof MultiPartBlockStateBuilder);
+            return (MultiPartBlockStateBuilder) old;
+        } else {
+            MultiPartBlockStateBuilder ret = new MultiPartBlockStateBuilder(b);
+            registeredBlocks.put(b, ret);
+            return ret;
+        }
+    }
+
+    private String name(Block block) {
+        return block.getRegistryName().getPath();
+    }
+
+    protected ResourceLocation blockTexture(Block block) {
+        ResourceLocation name = block.getRegistryName();
+        return new ResourceLocation(name.getNamespace(), BLOCK_FOLDER + "/" + name.getPath());
+    }
+
+    private ResourceLocation extend(ResourceLocation rl, String suffix) {
+        return new ResourceLocation(rl.getNamespace(), rl.getPath() + suffix);
+    }
+
+    protected ModelFile cubeAll(Block block) {
+        return cubeAll(name(block), blockTexture(block));
+    }
+
+    protected void simpleBlock(Block block) {
+        simpleBlock(block, cubeAll(block));
+    }
+
+    protected void simpleBlock(Block block, Function<ModelFile, ConfiguredModel[]> expander) {
+        simpleBlock(block, expander.apply(cubeAll(block)));
+    }
+
+    protected void simpleBlock(Block block, ModelFile model) {
+        simpleBlock(block, new ConfiguredModel(model));
+    }
+
+    protected void simpleBlock(Block block, ConfiguredModel... models) {
+        getVariantBuilder(block)
+            .partialState().setModels(models);
+    }
+
+    protected void axisBlock(RotatedPillarBlock block) {
+        axisBlock(block, blockTexture(block));
+    }
+
+    protected void logBlock(LogBlock block) {
+        axisBlock(block, blockTexture(block), extend(blockTexture(block), "_top"));
+    }
+
+    protected void axisBlock(RotatedPillarBlock block, ResourceLocation baseName) {
+        axisBlock(block, extend(baseName, "_side"), extend(baseName, "_end"));
+    }
+
+    protected void axisBlock(RotatedPillarBlock block, ResourceLocation side, ResourceLocation end) {
+        axisBlock(block, cubeColumn(name(block), side, end));
+    }
+
+    protected void axisBlock(RotatedPillarBlock block, ModelFile model) {
+        getVariantBuilder(block)
+            .partialState().with(RotatedPillarBlock.AXIS, Axis.Y)
+                .modelForState().modelFile(model).addModel()
+            .partialState().with(RotatedPillarBlock.AXIS, Axis.Z)
+                .modelForState().modelFile(model).rotationX(90).addModel()
+            .partialState().with(RotatedPillarBlock.AXIS, Axis.X)
+                .modelForState().modelFile(model).rotationX(90).rotationY(90).addModel();
+    }
+
+    private static final int DEFAULT_ANGLE_OFFSET = 180;
+
+    protected void horizontalBlock(Block block, ResourceLocation side, ResourceLocation front, ResourceLocation top) {
+        horizontalBlock(block, orientable(name(block), side, front, top));
+    }
+
+    protected void horizontalBlock(Block block, ModelFile model) {
+        horizontalBlock(block, model, DEFAULT_ANGLE_OFFSET);
+    }
+
+    protected void horizontalBlock(Block block, ModelFile model, int angleOffset) {
+        horizontalBlock(block, $ -> model, angleOffset);
+    }
+
+    protected void horizontalBlock(Block block, Function<BlockState, ModelFile> modelFunc) {
+        horizontalBlock(block, modelFunc, DEFAULT_ANGLE_OFFSET);
+    }
+
+    protected void horizontalBlock(Block block, Function<BlockState, ModelFile> modelFunc, int angleOffset) {
+        getVariantBuilder(block)
+            .forAllStates(state -> ConfiguredModel.builder()
+                    .modelFile(modelFunc.apply(state))
+                    .rotationY((int) state.get(BlockStateProperties.HORIZONTAL_FACING).getHorizontalAngle() + angleOffset)
+                    .build()
+            );
+    }
+
+    protected void horizontalFaceBlock(Block block, ModelFile model) {
+        horizontalFaceBlock(block, model, DEFAULT_ANGLE_OFFSET);
+    }
+
+    protected void horizontalFaceBlock(Block block, ModelFile model, int angleOffset) {
+        horizontalFaceBlock(block, $ -> model, angleOffset);
+    }
+
+    protected void horizontalFaceBlock(Block block, Function<BlockState, ModelFile> modelFunc) {
+        horizontalBlock(block, modelFunc, DEFAULT_ANGLE_OFFSET);
+    }
+
+    protected void horizontalFaceBlock(Block block, Function<BlockState, ModelFile> modelFunc, int angleOffset) {
+        getVariantBuilder(block)
+            .forAllStates(state -> ConfiguredModel.builder()
+                    .modelFile(modelFunc.apply(state))
+                    .rotationX(state.get(BlockStateProperties.FACE).ordinal() * 90)
+                    .rotationY((((int) state.get(BlockStateProperties.HORIZONTAL_FACING).getHorizontalAngle() + angleOffset) + (state.get(BlockStateProperties.FACE) == AttachFace.CEILING ? 180 : 0)) % 360)
+                    .build()
+            );
+    }
+
+    protected void directionalBlock(Block block, ModelFile model) {
+        directionalBlock(block, model, DEFAULT_ANGLE_OFFSET);
+    }
+
+    protected void directionalBlock(Block block, ModelFile model, int angleOffset) {
+        directionalBlock(block, $ -> model, angleOffset);
+    }
+
+    protected void directionalBlock(Block block, Function<BlockState, ModelFile> modelFunc) {
+        directionalBlock(block, modelFunc, DEFAULT_ANGLE_OFFSET);
+    }
+
+    protected void directionalBlock(Block block, Function<BlockState, ModelFile> modelFunc, int angleOffset) {
+        getVariantBuilder(block)
+            .forAllStates(state -> {
+                Direction dir = state.get(BlockStateProperties.FACING);
+                return ConfiguredModel.builder()
+                    .modelFile(modelFunc.apply(state))
+                    .rotationX(dir == Direction.DOWN ? 180 : dir.getAxis().isHorizontal() ? 90 : 0)
+                    .rotationY(dir.getAxis().isVertical() ? 0 : (((int) dir.getHorizontalAngle()) + angleOffset) % 360)
+                    .build();
+            });
+    }
+
+    protected void stairsBlock(StairsBlock block, ResourceLocation texture) {
+        stairsBlock(block, texture, texture, texture);
+    }
+
+    protected void stairsBlock(StairsBlock block, String name, ResourceLocation texture) {
+        stairsBlock(block, name, texture, texture, texture);
+    }
+
+    protected void stairsBlock(StairsBlock block, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        stairsBlockInternal(block, block.getRegistryName().toString(), side, bottom, top);
+    }
+
+    protected void stairsBlock(StairsBlock block, String name, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        stairsBlockInternal(block, name + "_stairs", side, bottom, top);
+    }
+
+    private void stairsBlockInternal(StairsBlock block, String baseName, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        ModelFile stairs = stairs(baseName, side, bottom, top);
+        ModelFile stairsInner = stairsInner(baseName + "_inner", side, bottom, top);
+        ModelFile stairsOuter = stairsOuter(baseName + "_outer", side, bottom, top);
+        stairsBlock(block, stairs, stairsInner, stairsOuter);
+    }
+
+    protected void stairsBlock(StairsBlock block, ModelFile stairs, ModelFile stairsInner, ModelFile stairsOuter) {
+        getVariantBuilder(block)
+            .forAllStatesExcept(state -> {
+               Direction facing = state.get(StairsBlock.FACING);
+               Half half = state.get(StairsBlock.HALF);
+               StairsShape shape = state.get(StairsBlock.SHAPE);
+               int yRot = (int) facing.rotateY().getHorizontalAngle(); // Stairs model is rotated 90 degrees clockwise for some reason
+               if (shape == StairsShape.INNER_LEFT || shape == StairsShape.OUTER_LEFT) {
+                   yRot += 270; // Left facing stairs are rotated 90 degrees clockwise
+               }
+               if (shape != StairsShape.STRAIGHT && half == Half.TOP) {
+                   yRot += 90; // Top stairs are rotated 90 degrees clockwise
+               }
+               yRot %= 360;
+               boolean uvlock = yRot != 0 || half == Half.TOP; // Don't set uvlock for states that have no rotation
+               return ConfiguredModel.builder()
+                       .modelFile(shape == StairsShape.STRAIGHT ? stairs : shape == StairsShape.INNER_LEFT || shape == StairsShape.INNER_RIGHT ? stairsInner : stairsOuter)
+                       .rotationX(half == Half.BOTTOM ? 0 : 180)
+                       .rotationY(yRot)
+                       .uvLock(uvlock)
+                       .build();
+            }, StairsBlock.WATERLOGGED);
+    }
+
+    protected void slabBlock(SlabBlock block, ResourceLocation doubleslab, ResourceLocation texture) {
+        slabBlock(block, doubleslab, texture, texture, texture);
+    }
+
+    protected void slabBlock(SlabBlock block, ResourceLocation doubleslab, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        slabBlock(block, slab(name(block), side, bottom, top), slabTop(name(block) + "_top", side, bottom, top), getExistingFile(doubleslab));
+    }
+
+    protected void slabBlock(SlabBlock block, ModelFile bottom, ModelFile top, ModelFile doubleslab) {
+        getVariantBuilder(block)
+            .partialState().with(SlabBlock.TYPE, SlabType.BOTTOM).addModels(new ConfiguredModel(bottom))
+            .partialState().with(SlabBlock.TYPE, SlabType.TOP).addModels(new ConfiguredModel(top))
+            .partialState().with(SlabBlock.TYPE, SlabType.DOUBLE).addModels(new ConfiguredModel(doubleslab));
+    }
+
+    protected void fourWayBlock(FourWayBlock block, ModelFile post, ModelFile side) {
+        MultiPartBlockStateBuilder builder = getMultipartBuilder(block)
+                .part().modelFile(post).addModel().end();
+        fourWayMultipart(builder, side);
+    }
+
+    protected void fourWayMultipart(MultiPartBlockStateBuilder builder, ModelFile side) {
+        SixWayBlock.FACING_TO_PROPERTY_MAP.entrySet().forEach(e -> {
+            Direction dir = e.getKey();
+            if (dir.getAxis().isHorizontal()) {
+                builder.part().modelFile(side).rotationY((((int) dir.getHorizontalAngle()) + 180) % 360).uvLock(true).addModel()
+                    .condition(e.getValue(), true);
+            }
+        });
+    }
+
+    protected void fenceBlock(FenceBlock block, ResourceLocation texture) {
+        String baseName = block.getRegistryName().toString();
+        fourWayBlock(block, fencePost(baseName + "_post", texture), fenceSide(baseName + "_side", texture));
+    }
+
+    protected void fenceBlock(FenceBlock block, String name, ResourceLocation texture) {
+        fourWayBlock(block, fencePost(name + "_fence_post", texture), fenceSide(name + "_fence_side", texture));
+    }
+
+    protected void fenceGateBlock(FenceGateBlock block, ResourceLocation texture) {
+        fenceGateBlockInternal(block, block.getRegistryName().toString(), texture);
+    }
+
+    protected void fenceGateBlock(FenceGateBlock block, String name, ResourceLocation texture) {
+        fenceGateBlockInternal(block, name + "_fence_gate", texture);
+    }
+
+    private void fenceGateBlockInternal(FenceGateBlock block, String baseName, ResourceLocation texture) {
+        ModelFile gate = fenceGate(baseName, texture);
+        ModelFile gateOpen = fenceGateOpen(baseName + "_open", texture);
+        ModelFile gateWall = fenceGateWall(baseName + "_wall", texture);
+        ModelFile gateWallOpen = fenceGateWallOpen(baseName + "_wall_open", texture);
+        fenceGateBlock(block, gate, gateOpen, gateWall, gateWallOpen);
+    }
+
+    protected void fenceGateBlock(FenceGateBlock block, ModelFile gate, ModelFile gateOpen, ModelFile gateWall, ModelFile gateWallOpen) {
+        getVariantBuilder(block).forAllStatesExcept(state -> {
+            ModelFile model = gate;
+            if (state.get(FenceGateBlock.IN_WALL)) {
+                model = gateWall;
+            }
+            if (state.get(FenceGateBlock.OPEN)) {
+                model = model == gateWall ? gateWallOpen : gateOpen;
+            }
+            return ConfiguredModel.builder()
+                    .modelFile(model)
+                    .rotationY((int) state.get(FenceGateBlock.HORIZONTAL_FACING).getHorizontalAngle())
+                    .uvLock(true)
+                    .build();
+        }, FenceGateBlock.POWERED);
+    }
+
+    protected void wallBlock(WallBlock block, ResourceLocation texture) {
+        wallBlockInternal(block, block.getRegistryName().toString(), texture);
+    }
+
+    protected void wallBlock(WallBlock block, String name, ResourceLocation texture) {
+        wallBlockInternal(block, name + "_wall", texture);
+    }
+
+    private void wallBlockInternal(WallBlock block, String baseName, ResourceLocation texture) {
+        wallBlock(block, wallPost(baseName + "_post", texture), wallSide(baseName + "_side", texture));
+    }
+
+    protected void wallBlock(WallBlock block, ModelFile post, ModelFile side) {
+        MultiPartBlockStateBuilder builder = getMultipartBuilder(block)
+                .part().modelFile(post).addModel()
+                    .condition(WallBlock.UP, true).end();
+        fourWayMultipart(builder, side);
+    }
+
+    protected void paneBlock(PaneBlock block, ResourceLocation pane, ResourceLocation edge) {
+        paneBlockInternal(block, block.getRegistryName().toString(), pane, edge);
+    }
+
+    protected void paneBlock(PaneBlock block, String name, ResourceLocation pane, ResourceLocation edge) {
+        paneBlockInternal(block, name + "_pane", pane, edge);
+    }
+
+    private void paneBlockInternal(PaneBlock block, String baseName, ResourceLocation pane, ResourceLocation edge) {
+        ModelFile post = panePost(baseName + "_post", pane, edge);
+        ModelFile side = paneSide(baseName + "_side", pane, edge);
+        ModelFile sideAlt = paneSideAlt(baseName + "_side_alt", pane, edge);
+        ModelFile noSide = paneNoSide(baseName + "_noside", pane);
+        ModelFile noSideAlt = paneNoSideAlt(baseName + "_noside_alt", pane);
+        paneBlock(block, post, side, sideAlt, noSide, noSideAlt);
+    }
+
+    protected void paneBlock(PaneBlock block, ModelFile post, ModelFile side, ModelFile sideAlt, ModelFile noSide, ModelFile noSideAlt) {
+        MultiPartBlockStateBuilder builder = getMultipartBuilder(block)
+                .part().modelFile(post).addModel().end();
+        SixWayBlock.FACING_TO_PROPERTY_MAP.entrySet().forEach(e -> {
+            Direction dir = e.getKey();
+            if (dir.getAxis().isHorizontal()) {
+                boolean alt = dir == Direction.SOUTH;
+                builder.part().modelFile(alt || dir == Direction.WEST ? sideAlt : side).rotationY(dir.getAxis() == Axis.X ? 90 : 0).addModel()
+                    .condition(e.getValue(), true).end()
+                .part().modelFile(alt || dir == Direction.EAST ? noSideAlt : noSide).rotationY(dir == Direction.WEST ? 270 : dir == Direction.SOUTH ? 90 : 0).addModel()
+                    .condition(e.getValue(), false);
+            }
+        });
+    }
+
+    protected void doorBlock(DoorBlock block, ResourceLocation bottom, ResourceLocation top) {
+        doorBlockInternal(block, block.getRegistryName().toString(), bottom, top);
+    }
+
+    protected void doorBlock(DoorBlock block, String name, ResourceLocation bottom, ResourceLocation top) {
+        doorBlockInternal(block, name + "_door", bottom, top);
+    }
+
+    private void doorBlockInternal(DoorBlock block, String baseName, ResourceLocation bottom, ResourceLocation top) {
+        ModelFile bottomLeft = doorBottomLeft(baseName + "_bottom", bottom, top);
+        ModelFile bottomRight = doorBottomRight(baseName + "_bottom_hinge", bottom, top);
+        ModelFile topLeft = doorTopLeft(baseName + "_top", bottom, top);
+        ModelFile topRight = doorTopRight(baseName + "_top_hinge", bottom, top);
+        doorBlock(block, bottomLeft, bottomRight, topLeft, topRight);
+    }
+
+    protected void doorBlock(DoorBlock block, ModelFile bottomLeft, ModelFile bottomRight, ModelFile topLeft, ModelFile topRight) {
+        getVariantBuilder(block).forAllStatesExcept(state -> {
+            int yRot = ((int) state.get(DoorBlock.FACING).getHorizontalAngle()) + 90;
+            boolean rh = state.get(DoorBlock.HINGE) == DoorHingeSide.RIGHT;
+            boolean open = state.get(DoorBlock.OPEN);
+            boolean right = rh ^ open;
+            if (open) {
+                yRot += 90;
+            }
+            if (rh && open) {
+                yRot += 180;
+            }
+            yRot %= 360;
+            return ConfiguredModel.builder().modelFile(state.get(DoorBlock.HALF) == DoubleBlockHalf.LOWER ? (right ? bottomRight : bottomLeft) : (right ? topRight : topLeft))
+                    .rotationY(yRot)
+                    .build();
+        }, DoorBlock.POWERED);
+    }
+
+    protected void trapdoorBlock(TrapDoorBlock block, ResourceLocation texture, boolean orientable) {
+        trapdoorBlockInternal(block, block.getRegistryName().toString(), texture, orientable);
+    }
+
+    protected void trapdoorBlock(TrapDoorBlock block, String name, ResourceLocation texture, boolean orientable) {
+        trapdoorBlockInternal(block, name + "_trapdoor", texture, orientable);
+    }
+
+    private void trapdoorBlockInternal(TrapDoorBlock block, String baseName, ResourceLocation texture, boolean orientable) {
+        ModelFile bottom = orientable ? trapdoorOrientableBottom(baseName + "_bottom", texture) : trapdoorBottom(baseName + "_bottom", texture);
+        ModelFile top = orientable ? trapdoorOrientableTop(baseName + "_top", texture) : trapdoorTop(baseName + "_top", texture);
+        ModelFile open = orientable ? trapdoorOrientableOpen(baseName + "_open", texture) : trapdoorOpen(baseName + "_open", texture);
+        trapdoorBlock(block, bottom, top, open, orientable);
+    }
+
+    protected void trapdoorBlock(TrapDoorBlock block, ModelFile bottom, ModelFile top, ModelFile open, boolean orientable) {
+        getVariantBuilder(block).forAllStatesExcept(state -> {
+            int xRot = 0;
+            int yRot = ((int) state.get(TrapDoorBlock.HORIZONTAL_FACING).getHorizontalAngle()) + 180;
+            boolean isOpen = state.get(TrapDoorBlock.OPEN);
+            if (orientable && isOpen && state.get(TrapDoorBlock.HALF) == Half.TOP) {
+                xRot += 180;
+                yRot += 180;
+            }
+            if (!orientable && !isOpen) {
+                yRot = 0;
+            }
+            yRot %= 360;
+            return ConfiguredModel.builder().modelFile(isOpen ? open : state.get(TrapDoorBlock.HALF) == Half.TOP ? top : bottom)
+                    .rotationX(xRot)
+                    .rotationY(yRot)
+                    .build();
+        }, TrapDoorBlock.POWERED, TrapDoorBlock.WATERLOGGED);
+    }
+
+    private void saveBlockState(JsonObject stateJson, Block owner) {
+        ResourceLocation blockName = Preconditions.checkNotNull(owner.getRegistryName());
+        Path mainOutput = generator.getOutputFolder();
+        String pathSuffix = "assets/" + blockName.getNamespace() + "/blockstates/" + blockName.getPath() + ".json";
+        Path outputPath = mainOutput.resolve(pathSuffix);
+        try {
+            IDataProvider.save(GSON, cache, stateJson, outputPath);
+        } catch (IOException e) {
+            LOGGER.error("Couldn't save blockstate to {}", outputPath, e);
+        }
+    }
+
+    @Nonnull
+    @Override
+    public String getName() {
+        return "Block States";
+    }
+
+    public static class ConfiguredModelList {
+        private final List<ConfiguredModel> models;
+
+        private ConfiguredModelList(List<ConfiguredModel> models) {
+            Preconditions.checkArgument(!models.isEmpty());
+            this.models = models;
+        }
+
+        public ConfiguredModelList(ConfiguredModel model) {
+            this(ImmutableList.of(model));
+        }
+
+        public ConfiguredModelList(ConfiguredModel... models) {
+            this(Arrays.asList(models));
+        }
+
+        public JsonElement toJSON() {
+            if (models.size()==1) {
+                return models.get(0).toJSON(false);
+            } else {
+                JsonArray ret = new JsonArray();
+                for (ConfiguredModel m:models) {
+                    ret.add(m.toJSON(true));
+                }
+                return ret;
+            }
+        }
+
+        public ConfiguredModelList append(ConfiguredModel... models) {
+            return new ConfiguredModelList(ImmutableList.<ConfiguredModel>builder().addAll(this.models).add(models).build());
+        }
+    }
+}

src/main/java/net/minecraftforge/client/model/generators/ConfiguredModel.java

@@ -0,0 +1,301 @@
+package net.minecraftforge.client.model.generators;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Function;
+import java.util.stream.IntStream;
+
+import javax.annotation.Nullable;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ObjectArrays;
+import com.google.gson.JsonObject;
+
+import net.minecraft.client.renderer.model.ModelRotation;
+import net.minecraftforge.client.model.generators.MultiPartBlockStateBuilder.PartBuilder;
+import net.minecraftforge.client.model.generators.VariantBlockStateBuilder.PartialBlockstate;
+
+/**
+ * Represents a model with blockstate configurations, e.g. rotation, uvlock, and
+ * random weight.
+ * <p>
+ * Can be manually constructed, created by static factory such as
+ * {@link #allYRotations(ModelFile, int, boolean)}, or created by builder via
+ * {@link #builder()}.
+ */
+public final class ConfiguredModel {
+
+    /**
+     * The default random weight of configured models, used by convenience
+     * overloads.
+     */
+    public static final int DEFAULT_WEIGHT = 1;
+
+    public final ModelFile model;
+    public final int rotationX;
+    public final int rotationY;
+    public final boolean uvLock;
+    public final int weight;
+
+    private static IntStream validRotations() {
+        return IntStream.range(0, 4).map(i -> i * 90);
+    }
+
+    public static ConfiguredModel[] allYRotations(ModelFile model, int x, boolean uvlock) {
+        return allYRotations(model, x, uvlock, DEFAULT_WEIGHT);
+    }
+
+    public static ConfiguredModel[] allYRotations(ModelFile model, int x, boolean uvlock, int weight) {
+        return validRotations()
+                .mapToObj(y -> new ConfiguredModel(model, x, y, uvlock, weight))
+                .toArray(ConfiguredModel[]::new);
+    }
+
+    public static ConfiguredModel[] allRotations(ModelFile model, boolean uvlock) {
+        return allRotations(model, uvlock, DEFAULT_WEIGHT);
+    }
+
+    public static ConfiguredModel[] allRotations(ModelFile model, boolean uvlock, int weight) {
+        return validRotations()
+                .mapToObj(x -> allYRotations(model, x, uvlock, weight))
+                .flatMap(Arrays::stream)
+                .toArray(ConfiguredModel[]::new);
+    }
+
+    /**
+     * Construct a new {@link ConfiguredModel}.
+     * 
+     * @param model     the underlying model
+     * @param rotationX x-rotation to apply to the model
+     * @param rotationY y-rotation to apply to the model
+     * @param uvLock    if uvlock should be enabled
+     * @param weight    the random weight of the model
+     * 
+     * @throws NullPointerException     if {@code model} is {@code null}
+     * @throws IllegalArgumentException if x and/or y rotation are not valid (see
+     *                                  {@link ModelRotation})
+     * @throws IllegalArgumentException if weight is less than or equal to zero
+     */
+    public ConfiguredModel(ModelFile model, int rotationX, int rotationY, boolean uvLock, int weight) {
+        Preconditions.checkNotNull(model);
+        this.model = model;
+        checkRotation(rotationX, rotationY);
+        this.rotationX = rotationX;
+        this.rotationY = rotationY;
+        this.uvLock = uvLock;
+        checkWeight(weight);
+        this.weight = weight;
+    }
+
+    /**
+     * Construct a new {@link ConfiguredModel} with the {@link #DEFAULT_WEIGHT
+     * default random weight}.
+     * 
+     * @param model     the underlying model
+     * @param rotationX x-rotation to apply to the model
+     * @param rotationY y-rotation to apply to the model
+     * @param uvLock    if uvlock should be enabled
+     * 
+     * @throws NullPointerException     if {@code model} is {@code null}
+     * @throws IllegalArgumentException if x and/or y rotation are not valid (see
+     *                                  {@link ModelRotation})
+     */
+    public ConfiguredModel(ModelFile model, int rotationX, int rotationY, boolean uvLock) {
+        this(model, rotationX, rotationY, uvLock, DEFAULT_WEIGHT);
+    }
+
+    /**
+     * Construct a new {@link ConfiguredModel} with the default rotation (0, 0),
+     * uvlock (false), and {@link #DEFAULT_WEIGHT default random weight}.
+     * 
+     * @throws NullPointerException if {@code model} is {@code null}
+     */
+    public ConfiguredModel(ModelFile model) {
+        this(model, 0, 0, false);
+    }
+
+    static void checkRotation(int rotationX, int rotationY) {
+        Preconditions.checkArgument(ModelRotation.getModelRotation(rotationX, rotationY) != null, "Invalid model rotation x=%d, y=%d", rotationX, rotationY);
+    }
+
+    static void checkWeight(int weight) {
+        Preconditions.checkArgument(weight >= 1, "Model weight must be greater than or equal to 1. Found: %d", weight);
+    }
+
+    JsonObject toJSON(boolean includeWeight) {
+        JsonObject modelJson = new JsonObject();
+        modelJson.addProperty("model", model.getLocation().toString());
+        if (rotationX != 0)
+            modelJson.addProperty("x", rotationX);
+        if (rotationY != 0)
+            modelJson.addProperty("y", rotationY);
+        if (uvLock)
+            modelJson.addProperty("uvlock", uvLock);
+        if (includeWeight && weight != DEFAULT_WEIGHT)
+            modelJson.addProperty("weight", weight);
+        return modelJson;
+    }
+
+    /**
+     * Create a new unowned {@link Builder}.
+     * 
+     * @return the builder
+     * @see Builder
+     */
+    public static Builder<?> builder() {
+        return new Builder<>();
+    }
+
+    static Builder<VariantBlockStateBuilder> builder(VariantBlockStateBuilder outer, VariantBlockStateBuilder.PartialBlockstate state) {
+        return new Builder<>(models -> outer.setModels(state, models), ImmutableList.of());
+    }
+
+    static Builder<PartBuilder> builder(MultiPartBlockStateBuilder outer) {
+        return new Builder<PartBuilder>(models -> {
+            PartBuilder ret = outer.new PartBuilder(new BlockStateProvider.ConfiguredModelList(models));
+            outer.addPart(ret);
+            return ret;
+        }, ImmutableList.of());
+    }
+
+    /**
+     * A builder for {@link ConfiguredModel}s, which can contain a callback for
+     * processing the finished result. If no callback is available (e.g. in the case
+     * of {@link ConfiguredModel#builder()}), some methods will not be available.
+     * <p>
+     * Multiple models can be configured at once through the use of
+     * {@link #nextModel()}.
+     *
+     * @param <T> the type of the owning builder, which supplied the callback, and
+     *            will be returned upon completion.
+     */
+    public static class Builder<T> {
+
+        private ModelFile model;
+        @Nullable
+        private final Function<ConfiguredModel[], T> callback;
+        private final List<ConfiguredModel> otherModels;
+        private int rotationX;
+        private int rotationY;
+        private boolean uvLock;
+        private int weight = DEFAULT_WEIGHT;
+
+        Builder() {
+            this(null, ImmutableList.of());
+        }
+
+        Builder(@Nullable Function<ConfiguredModel[], T> callback, List<ConfiguredModel> otherModels) {
+            this.callback = callback;
+            this.otherModels = otherModels;
+        }
+
+        /**
+         * Set the underlying model object for this configured model.
+         * 
+         * @param model the model
+         * @return this builder
+         * @throws NullPointerException if {@code model} is {@code null}
+         */
+        public Builder<T> modelFile(ModelFile model) {
+            Preconditions.checkNotNull(model, "Model must not be null");
+            this.model = model;
+            return this;
+        }
+
+        /**
+         * Set the x-rotation for this model.
+         * 
+         * @param value the x-rotation value
+         * @return this builder
+         * @throws IllegalArgumentException if {@code value} is not a valid x-rotation
+         *                                  (see {@link ModelRotation})
+         */
+        public Builder<T> rotationX(int value) {
+            checkRotation(value, rotationY);
+            rotationX = value;
+            return this;
+        }
+
+        /**
+         * Set the y-rotation for this model.
+         * 
+         * @param value the y-rotation value
+         * @return this builder
+         * @throws IllegalArgumentException if {@code value} is not a valid y-rotation
+         *                                  (see {@link ModelRotation})
+         */
+        public Builder<T> rotationY(int value) {
+            checkRotation(rotationX, value);
+            rotationY = value;
+            return this;
+        }
+
+        public Builder<T> uvLock(boolean value) {
+            uvLock = value;
+            return this;
+        }
+
+        /**
+         * Set the random weight for this model.
+         * 
+         * @param value the weight value
+         * @return this builder
+         * @throws IllegalArgumentException if {@code value} is less than or equal to
+         *                                  zero
+         */
+        public Builder<T> weight(int value) {
+            checkWeight(value);
+            weight = value;
+            return this;
+        }
+
+        /**
+         * Build the most recent model, as if {@link #nextModel()} was never called.
+         * Useful for single-model builders.
+         * 
+         * @return the most recently configured model
+         */
+        public ConfiguredModel buildLast() {
+            return new ConfiguredModel(model, rotationX, rotationY, uvLock, weight);
+        }
+
+        /**
+         * Build all configured models and return them as an array.
+         * 
+         * @return the array of built models.
+         */
+        public ConfiguredModel[] build() {
+            return ObjectArrays.concat(otherModels.toArray(new ConfiguredModel[0]), buildLast());
+        }
+
+        /**
+         * Apply the contained callback and return the owning builder object. What the
+         * callback does is not defined by this class, but most likely it adds the built
+         * models to the current variant being configured.
+         * <p>
+         * Known callbacks include:
+         * <ul>
+         * <li>{@link PartialBlockstate#modelForState()}</li>
+         * <li>{@link MultiPartBlockStateBuilder#part()}</li>
+         * </ul>
+         * 
+         * @return the owning builder object
+         * @throws NullPointerException if there is no owning builder (and thus no callback)
+         */
+        public T addModel() {
+            Preconditions.checkNotNull(callback, "Cannot use addModel() without an owning builder present");
+            return callback.apply(build());
+        }
+
+        /**
+         * Complete the current model and return a new builder instance with the same
+         * callback, and storing all previously built models.
+         * 
+         * @return a new builder for configuring the next model
+         */
+        public Builder<T> nextModel() {
+            return new Builder<>(callback, Arrays.asList(build()));
+        }
+    }
+}

src/main/java/net/minecraftforge/client/model/generators/ExistingFileHelper.java

@@ -0,0 +1,84 @@
+package net.minecraftforge.client.model.generators;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.Collection;
+
+import com.google.common.annotations.VisibleForTesting;
+
+import net.minecraft.resources.FilePack;
+import net.minecraft.resources.FolderPack;
+import net.minecraft.resources.IResource;
+import net.minecraft.resources.IResourceManager;
+import net.minecraft.resources.IResourcePack;
+import net.minecraft.resources.ResourcePackType;
+import net.minecraft.resources.SimpleReloadableResourceManager;
+import net.minecraft.resources.VanillaPack;
+import net.minecraft.util.ResourceLocation;
+import net.minecraftforge.fml.event.lifecycle.GatherDataEvent;
+
+/**
+ * Enables data providers to check if other data files currently exist. The
+ * instance provided in the {@link GatherDataEvent} utilizes the standard
+ * resources (via {@link VanillaPack}), as well as any extra resource packs
+ * passed in via the {@code --existing} argument.
+ */
+public class ExistingFileHelper {
+
+    private final IResourceManager clientResources, serverData;
+    private final boolean enable;
+
+    public ExistingFileHelper(Collection<Path> existingPacks, boolean enable) {
+        this.clientResources = new SimpleReloadableResourceManager(ResourcePackType.CLIENT_RESOURCES, Thread.currentThread());
+        this.serverData = new SimpleReloadableResourceManager(ResourcePackType.SERVER_DATA, Thread.currentThread());
+        this.clientResources.addResourcePack(new VanillaPack("minecraft", "realms"));
+        this.serverData.addResourcePack(new VanillaPack("minecraft"));
+        for (Path existing : existingPacks) {
+            File file = existing.toFile();
+            IResourcePack pack = file.isDirectory() ? new FolderPack(file) : new FilePack(file);
+            this.clientResources.addResourcePack(pack);
+            this.serverData.addResourcePack(pack);
+        };
+        this.enable = enable;
+    }
+
+    private IResourceManager getManager(ResourcePackType type) {
+        return type == ResourcePackType.CLIENT_RESOURCES ? clientResources : serverData;
+    }
+
+    private ResourceLocation getLocation(ResourceLocation base, String suffix, String prefix) {
+        return new ResourceLocation(base.getNamespace(), prefix + "/" + base.getPath() + suffix);
+    }
+
+    /**
+     * Check if a given resource exists in the known resource packs.
+     * 
+     * @param loc        the base location of the resource, e.g.
+     *                   {@code "minecraft:block/stone"}
+     * @param type       the type of resources to check
+     * @param pathSuffix a string to append after the path, e.g. {@code ".json"}
+     * @param pathPrefix a string to append before the path, before a slash, e.g.
+     *                   {@code "models"}
+     * @return {@code true} if the resource exists in any pack, {@code false}
+     *         otherwise
+     */
+    public boolean exists(ResourceLocation loc, ResourcePackType type, String pathSuffix, String pathPrefix) {
+        if (!enable) {
+            return true;
+        }
+        return getManager(type).hasResource(getLocation(loc, pathSuffix, pathPrefix));
+    }
+
+    @VisibleForTesting
+    public IResource getResource(ResourceLocation loc, ResourcePackType type, String pathSuffix, String pathPrefix) throws IOException {
+        return getManager(type).getResource(getLocation(loc, pathSuffix, pathPrefix));
+    }
+
+    /**
+     * @return {@code true} if validation is enabled, {@code false} otherwise
+     */
+    public boolean isEnabled() {
+        return enable;
+    }
+}

src/main/java/net/minecraftforge/client/model/generators/IGeneratedBlockstate.java

@@ -0,0 +1,10 @@
+package net.minecraftforge.client.model.generators;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.gson.JsonObject;
+
+@VisibleForTesting
+public interface IGeneratedBlockstate {
+
+    JsonObject toJson();
+}

src/main/java/net/minecraftforge/client/model/generators/ItemModelBuilder.java

@@ -0,0 +1,102 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2019.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.client.model.generators;
+
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+import com.google.common.base.Preconditions;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonObject;
+
+import net.minecraft.util.ResourceLocation;
+
+/**
+ * Builder for item models, adds the ability to build overrides via
+ * {@link #override()}.
+ */
+public class ItemModelBuilder extends ModelBuilder<ItemModelBuilder> {
+
+    protected List<OverrideBuilder> overrides = new ArrayList<>();
+
+    public ItemModelBuilder(ResourceLocation outputLocation, ExistingFileHelper existingFileHelper) {
+        super(outputLocation, existingFileHelper);
+    }
+
+    public OverrideBuilder override() {
+        OverrideBuilder ret = new OverrideBuilder();
+        overrides.add(ret);
+        return ret;
+    }
+
+    /**
+     * Get an existing override builder
+     * 
+     * @param index the index of the existing override builder
+     * @return the override builder
+     * @throws IndexOutOfBoundsException if {@code} index is out of bounds
+     */
+    public OverrideBuilder override(int index) {
+        Preconditions.checkElementIndex(index, overrides.size(), "override");
+        return overrides.get(index);
+    }
+
+    @Override
+    public JsonObject toJson() {
+        JsonObject root = super.toJson();
+        if (!overrides.isEmpty()) {
+            JsonArray overridesJson = new JsonArray();
+            overrides.stream().map(OverrideBuilder::toJson).forEach(overridesJson::add);
+            root.add("overrides", overridesJson);
+        }
+        return root;
+    }
+
+    public class OverrideBuilder {
+
+        private ModelFile model;
+        private final Map<ResourceLocation, Float> predicates = new LinkedHashMap<>();
+
+        public OverrideBuilder model(ModelFile model) {
+            this.model = model;
+            model.assertExistence();
+            return this;
+        }
+
+        public OverrideBuilder predicate(ResourceLocation key, float value) {
+            this.predicates.put(key, value);
+            return this;
+        }
+
+        public ItemModelBuilder end() { return ItemModelBuilder.this; }
+
+        JsonObject toJson() {
+            JsonObject ret = new JsonObject();
+            JsonObject predicatesJson = new JsonObject();
+            predicates.forEach((key, val) -> predicatesJson.addProperty(serializeLoc(key), val));
+            ret.add("predicate", predicatesJson);
+            ret.addProperty("model", serializeLoc(model.getLocation()));
+            return ret;
+        }
+    }
+
+}

src/main/java/net/minecraftforge/client/model/generators/ItemModelProvider.java

@@ -0,0 +1,14 @@
+package net.minecraftforge.client.model.generators;
+
+import net.minecraft.data.DataGenerator;
+
+/**
+ * Stub class to extend for item model data providers, eliminates some
+ * boilerplate constructor parameters.
+ */
+public abstract class ItemModelProvider extends ModelProvider<ItemModelBuilder> {
+
+    public ItemModelProvider(DataGenerator generator, String modid, ExistingFileHelper existingFileHelper) {
+        super(generator, modid, ITEM_FOLDER, ItemModelBuilder::new, existingFileHelper);
+    }
+}

src/main/java/net/minecraftforge/client/model/generators/ModelBuilder.java

@@ -0,0 +1,666 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2019.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.client.model.generators;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.function.BiConsumer;
+import java.util.stream.Collectors;
+
+import javax.annotation.Nullable;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
+import com.google.gson.Gson;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonObject;
+
+import net.minecraft.client.renderer.Vector3f;
+import net.minecraft.client.renderer.model.BlockFaceUV;
+import net.minecraft.client.renderer.model.BlockPart;
+import net.minecraft.client.renderer.model.BlockPartFace;
+import net.minecraft.client.renderer.model.BlockPartRotation;
+import net.minecraft.client.renderer.model.ItemCameraTransforms.TransformType;
+import net.minecraft.client.renderer.model.ItemTransformVec3f;
+import net.minecraft.client.renderer.texture.MissingTextureSprite;
+import net.minecraft.resources.ResourcePackType;
+import net.minecraft.util.Direction;
+import net.minecraft.util.ResourceLocation;
+import net.minecraft.util.math.MathHelper;
+
+/**
+ * General purpose model builder, contains all the commonalities between item
+ * and block models.
+ * 
+ * @see ModelProvider
+ * @see BlockModelBuilder
+ * @see ItemModelBuilder
+ * 
+ * @param <T> Self type, for simpler chaining of methods.
+ */
+@SuppressWarnings("deprecation")
+public class ModelBuilder<T extends ModelBuilder<T>> extends ModelFile {
+
+    @Nullable
+    protected ModelFile parent;
+    protected final Map<String, String> textures = new LinkedHashMap<>();
+    protected final TransformsBuilder transforms = new TransformsBuilder();
+    protected final ExistingFileHelper existingFileHelper;
+
+    protected boolean ambientOcclusion = true;
+    protected boolean gui3d = false;
+
+    protected final List<ElementBuilder> elements = new ArrayList<>();
+
+    protected ModelBuilder(ResourceLocation outputLocation, ExistingFileHelper existingFileHelper) {
+        super(outputLocation);
+        this.existingFileHelper = existingFileHelper;
+    }
+
+    @SuppressWarnings("unchecked")
+    private T self() { return (T) this; }
+
+    @Override
+    protected boolean exists() {
+        return true;
+    }
+
+    /**
+     * Set the parent model for the current model.
+     * 
+     * @param parent the parent model
+     * @return this builder
+     * @throws NullPointerException  if {@code parent} is {@code null}
+     * @throws IllegalStateException if {@code parent} does not {@link ModelFile#assertExistence() exist}
+     */
+    public T parent(ModelFile parent) {
+        Preconditions.checkNotNull(parent, "Parent must not be null");
+        parent.assertExistence();
+        this.parent = parent;
+        return self();
+    }
+
+    /**
+     * Set the texture for a given dictionary key.
+     * 
+     * @param key     the texture key
+     * @param texture the texture, can be another key e.g. {@code "#all"}
+     * @return this builder
+     * @throws NullPointerException  if {@code key} is {@code null}
+     * @throws NullPointerException  if {@code texture} is {@code null}
+     * @throws IllegalStateException if {@code texture} is not a key (does not start
+     *                               with {@code '#'}) and does not exist in any
+     *                               known resource pack
+     */
+    public T texture(String key, String texture) {
+        Preconditions.checkNotNull(key, "Key must not be null");
+        Preconditions.checkNotNull(texture, "Texture must not be null");
+        if (texture.charAt(0) == '#') {
+            this.textures.put(key, texture);
+            return self();
+        } else {
+            ResourceLocation asLoc;
+            if (texture.contains(":")) {
+                asLoc = new ResourceLocation(texture);
+            } else {
+                asLoc = new ResourceLocation(getLocation().getNamespace(), texture);
+            }
+            return texture(key, asLoc);
+        }
+    }
+
+    /**
+     * Set the texture for a given dictionary key.
+     * 
+     * @param key     the texture key
+     * @param texture the texture
+     * @return this builder
+     * @throws NullPointerException  if {@code key} is {@code null}
+     * @throws NullPointerException  if {@code texture} is {@code null}
+     * @throws IllegalStateException if {@code texture} is not a key (does not start
+     *                               with {@code '#'}) and does not exist in any
+     *                               known resource pack
+     */
+    public T texture(String key, ResourceLocation texture) {
+        Preconditions.checkNotNull(key, "Key must not be null");
+        Preconditions.checkNotNull(texture, "Texture must not be null");
+        Preconditions.checkArgument(existingFileHelper.exists(texture, ResourcePackType.CLIENT_RESOURCES, ".png", "textures"),
+                "Texture %s does not exist in any known resource pack", texture);
+        this.textures.put(key, texture.toString());
+        return self();
+    }
+
+    public TransformsBuilder transforms() {
+        return transforms;
+    }
+
+    public T ao(boolean ao) {
+        this.ambientOcclusion = ao;
+        return self();
+    }
+
+    public T gui3d(boolean gui3d) {
+        this.gui3d = gui3d;
+        return self();
+    }
+
+    public ElementBuilder element() {
+        ElementBuilder ret = new ElementBuilder();
+        elements.add(ret);
+        return ret;
+    }
+
+    /**
+     * Get an existing element builder
+     * 
+     * @param index the index of the existing element builder
+     * @return the element builder
+     * @throws IndexOutOfBoundsException if {@code} index is out of bounds
+     */
+    public ElementBuilder element(int index) {
+        Preconditions.checkElementIndex(index, elements.size(), "Element index");
+        return elements.get(index);
+    }
+
+    @VisibleForTesting
+    public JsonObject toJson() {
+        JsonObject root = new JsonObject();
+        if (this.parent != null) {
+            root.addProperty("parent", serializeLoc(this.parent.getLocation()));
+        }
+
+        if (!this.ambientOcclusion) {
+            root.addProperty("ambientocclusion", this.ambientOcclusion);
+        }
+
+        Map<Perspective, ItemTransformVec3f> transforms = this.transforms.build();
+        if (!transforms.isEmpty()) {
+            JsonObject display = new JsonObject();
+            for (Entry<Perspective, ItemTransformVec3f> e : transforms.entrySet()) {
+                JsonObject transform = new JsonObject();
+                ItemTransformVec3f vec = e.getValue();
+                if (vec.equals(ItemTransformVec3f.DEFAULT)) continue;
+                if (!vec.rotation.equals(ItemTransformVec3f.Deserializer.ROTATION_DEFAULT)) {
+                    transform.add("rotation", serializeVector3f(vec.rotation));
+                }
+                if (!vec.translation.equals(ItemTransformVec3f.Deserializer.TRANSLATION_DEFAULT)) {
+                    transform.add("translation", serializeVector3f(e.getValue().translation));
+                }
+                if (!vec.scale.equals(ItemTransformVec3f.Deserializer.SCALE_DEFAULT)) {
+                    transform.add("scale", serializeVector3f(e.getValue().scale));
+                }
+                display.add(e.getKey().name, transform);
+            }
+            root.add("display", display);
+        }
+
+        if (!this.textures.isEmpty()) {
+            JsonObject textures = new JsonObject();
+            for (Entry<String, String> e : this.textures.entrySet()) {
+                textures.addProperty(e.getKey(), serializeLocOrKey(e.getValue()));
+            }
+            root.add("textures", textures);
+        }
+
+        if (!this.elements.isEmpty()) {
+            JsonArray elements = new JsonArray();
+            this.elements.stream().map(ElementBuilder::build).forEach(part -> { 
+                JsonObject partObj = new JsonObject();
+                partObj.add("from", serializeVector3f(part.positionFrom));
+                partObj.add("to", serializeVector3f(part.positionTo));
+
+                if (part.partRotation != null) {
+                    JsonObject rotation = new JsonObject();
+                    rotation.add("origin", serializeVector3f(part.partRotation.origin));
+                    rotation.addProperty("axis", part.partRotation.axis.getName());
+                    rotation.addProperty("angle", part.partRotation.angle);
+                    if (part.partRotation.rescale) {
+                        rotation.addProperty("rescale", part.partRotation.rescale);
+                    }
+                    partObj.add("rotation", rotation);
+                }
+
+                if (!part.shade) {
+                    partObj.addProperty("shade", part.shade);
+                }
+
+                JsonObject faces = new JsonObject();
+                for (Direction dir : Direction.values()) {
+                    BlockPartFace face = part.mapFaces.get(dir);
+                    if (face == null) continue;
+
+                    JsonObject faceObj = new JsonObject();
+                    faceObj.addProperty("texture", serializeLocOrKey(face.texture));
+                    if (!Arrays.equals(face.blockFaceUV.uvs, part.getFaceUvs(dir))) {
+                        faceObj.add("uv", new Gson().toJsonTree(face.blockFaceUV.uvs));
+                    }
+                    if (face.cullFace != null) {
+                        faceObj.addProperty("cullface", face.cullFace.getName());
+                    }
+                    if (face.blockFaceUV.rotation != 0) {
+                        faceObj.addProperty("rotation", face.blockFaceUV.rotation);
+                    }
+                    if (face.tintIndex != -1) {
+                        faceObj.addProperty("tintindex", face.tintIndex);
+                    }
+                    faces.add(dir.getName(), faceObj);
+                }
+                if (!part.mapFaces.isEmpty()) {
+                    partObj.add("faces", faces);
+                }
+                elements.add(partObj);
+            });
+            root.add("elements", elements);
+        }
+
+        return root;
+    }
+
+    private String serializeLocOrKey(String tex) {
+        if (tex.charAt(0) == '#') {
+            return tex;
+        }
+        return serializeLoc(new ResourceLocation(tex));
+    }
+
+    String serializeLoc(ResourceLocation loc) {
+        if (loc.getNamespace().equals("minecraft")) {
+            return loc.getPath();
+        }
+        return loc.toString();
+    }
+
+    private JsonArray serializeVector3f(Vector3f vec) {
+        JsonArray ret = new JsonArray();
+        ret.add(serializeFloat(vec.getX()));
+        ret.add(serializeFloat(vec.getY()));
+        ret.add(serializeFloat(vec.getZ()));
+        return ret;
+    }
+
+    private Number serializeFloat(float f) {
+        if ((int) f == f) {
+            return (int) f;
+        }
+        return f;
+    }
+
+    public class ElementBuilder {
+
+        private Vector3f from = new Vector3f();
+        private Vector3f to = new Vector3f(16, 16, 16);
+        private final Map<Direction, FaceBuilder> faces = new LinkedHashMap<>();
+        private RotationBuilder rotation;
+        private boolean shade = true;
+
+        private void validateCoordinate(float coord, char name) {
+            Preconditions.checkArgument(!(coord < -16.0F) && !(coord > 32.0F), "Position " + name + " out of range, must be within [-16, 32]. Found: %d", coord);
+        }
+
+        private void validatePosition(Vector3f pos) {
+            validateCoordinate(pos.getX(), 'x');
+            validateCoordinate(pos.getY(), 'y');
+            validateCoordinate(pos.getZ(), 'z');
+        }
+
+        /**
+         * Set the "from" position for this element.
+         * 
+         * @param x x-position for this vector
+         * @param y y-position for this vector
+         * @param z z-position for this vector
+         * @return this builder
+         * @throws IllegalArgumentException if the vector is out of bounds (any
+         *                                  coordinate not between -16 and 32,
+         *                                  inclusive)
+         */
+        public ElementBuilder from(float x, float y, float z) {
+            this.from = new Vector3f(x, y, z);
+            validatePosition(this.from);
+            return this;
+        }
+
+        /**
+         * Set the "to" position for this element.
+         * 
+         * @param x x-position for this vector
+         * @param y y-position for this vector
+         * @param z z-position for this vector
+         * @return this builder
+         * @throws IllegalArgumentException if the vector is out of bounds (any
+         *                                  coordinate not between -16 and 32,
+         *                                  inclusive)
+         */
+        public ElementBuilder to(float x, float y, float z) {
+            this.to = new Vector3f(x, y, z);
+            validatePosition(this.to);
+            return this;
+        }
+
+        /**
+         * Return or create the face builder for the given direction.
+         * 
+         * @param dir the direction
+         * @return the face builder for the given direction
+         * @throws NullPointerException if {@code dir} is {@code null}
+         */
+        public FaceBuilder face(Direction dir) {
+            Preconditions.checkNotNull(dir, "Direction must not be null");
+            return faces.computeIfAbsent(dir, FaceBuilder::new);
+        }
+
+        public RotationBuilder rotation(BlockPartRotation rotation) {
+            if (this.rotation == null) {
+                this.rotation = new RotationBuilder();
+            }
+            return this.rotation;
+        }
+
+        public ElementBuilder shade(boolean shade) {
+            this.shade = shade;
+            return this;
+        }
+
+        /**
+         * Modify all <em>possible</em> faces dynamically using a function, creating new
+         * faces as necessary.
+         * 
+         * @param action the function to apply to each direction
+         * @return this builder
+         * @throws NullPointerException if {@code action} is {@code null}
+         */
+        public ElementBuilder allFaces(BiConsumer<Direction, FaceBuilder> action) {
+            Arrays.stream(Direction.values())
+                .forEach(d -> action.accept(d, face(d)));
+            return this;
+        }
+
+        /**
+         * Modify all <em>existing</em> faces dynamically using a function.
+         * 
+         * @param action the function to apply to each direction
+         * @return this builder
+         * @throws NullPointerException if {@code action} is {@code null}
+         */
+        public ElementBuilder faces(BiConsumer<Direction, FaceBuilder> action) {
+            faces.entrySet().stream()
+                .forEach(e -> action.accept(e.getKey(), e.getValue()));
+            return this;
+        }
+
+        /**
+         * Texture all <em>possible</em> faces in the current element with the given
+         * texture, creating new faces where necessary.
+         * 
+         * @param texture the texture
+         * @return this builder
+         * @throws NullPointerException if {@code texture} is {@code null}
+         */
+        public ElementBuilder textureAll(String texture) {
+            return allFaces(addTexture(texture));
+        }
+
+        /**
+         * Texture all <em>existing</em> faces in the current element with the given
+         * texture.
+         * 
+         * @param texture the texture
+         * @return this builder
+         * @throws NullPointerException if {@code texture} is {@code null}
+         */
+        public ElementBuilder texture(String texture) {
+            return faces(addTexture(texture));
+        }
+
+        /**
+         * Create a typical cube element, creating new faces as needed, applying the
+         * given texture, and setting the cullface.
+         * 
+         * @param texture the texture
+         * @return this builder
+         * @throws NullPointerException if {@code texture} is {@code null}
+         */
+        public ElementBuilder cube(String texture) {
+            return allFaces(addTexture(texture).andThen((dir, f) -> f.cullface(dir)));
+        }
+
+        private BiConsumer<Direction, FaceBuilder> addTexture(String texture) {
+            return ($, f) -> f.texture(texture);
+        }
+
+        BlockPart build() {
+            Map<Direction, BlockPartFace> faces = this.faces.entrySet().stream()
+                    .collect(Collectors.toMap(Map.Entry::getKey, e -> e.getValue().build(), (k1, k2) -> { throw new IllegalArgumentException(); }, LinkedHashMap::new));
+            return new BlockPart(from, to, faces, rotation == null ? null : rotation.build(), shade);
+        }
+
+        public T end() { return self(); }
+
+        public class FaceBuilder {
+
+            private Direction cullface;
+            private int tintindex = -1;
+            private String texture = MissingTextureSprite.getLocation().toString();
+            private float[] uvs;
+            private FaceRotation rotation = FaceRotation.ZERO;
+
+            FaceBuilder(Direction dir) {
+                // param unused for functional match
+            }
+
+            public FaceBuilder cullface(@Nullable Direction dir) {
+                this.cullface = dir;
+                return this;
+            }
+
+            public FaceBuilder tintindex(int index) {
+                this.tintindex = index;
+                return this;
+            }
+
+            /**
+             * Set the texture for the current face.
+             * 
+             * @param texture the texture
+             * @return this builder
+             * @throws NullPointerException if {@code texture} is {@code null}
+             */
+            public FaceBuilder texture(String texture) {
+                Preconditions.checkNotNull(texture, "Texture must not be null");
+                this.texture = texture;
+                return this;
+            }
+
+            public FaceBuilder uvs(float u1, float v1, float u2, float v2) {
+                this.uvs = new float[] { u1, v1, u2, v2 };
+                return this;
+            }
+
+            /**
+             * Set the texture rotation for the current face.
+             * 
+             * @param rot the rotation
+             * @return this builder
+             * @throws NullPointerException if {@code rot} is {@code null}
+             */
+            public FaceBuilder rotation(FaceRotation rot) {
+                Preconditions.checkNotNull(rot, "Rotation must not be null");
+                this.rotation = rot;
+                return this;
+            }
+
+            BlockPartFace build() {
+                if (this.texture == null) {
+                    throw new IllegalStateException("A model face must have a texture");
+                }
+                return new BlockPartFace(cullface, tintindex, texture, new BlockFaceUV(uvs, rotation.rotation));
+            }
+
+            public ElementBuilder end() { return ElementBuilder.this; }
+        }
+
+        public class RotationBuilder {
+
+            private Vector3f origin;
+            private Direction.Axis axis;
+            private float angle;
+            private boolean rescale;
+
+            public RotationBuilder origin(float x, float y, float z) {
+                this.origin = new Vector3f(x, y, z);
+                return this;
+            }
+
+            /**
+             * @param axis the axis of rotation
+             * @return this builder
+             * @throws NullPointerException if {@code axis} is {@code null}
+             */
+            public RotationBuilder axis(Direction.Axis axis) {
+                Preconditions.checkNotNull(axis, "Axis must not be null");
+                this.axis = axis;
+                return this;
+            }
+
+            /**
+             * @param angle the rotation angle
+             * @return this builder
+             * @throws IllegalArgumentException if {@code angle} is invalid (not one of 0, +/-22.5, +/-45)
+             */
+            public RotationBuilder angle(float angle) {
+                // Same logic from BlockPart.Deserializer#parseAngle
+                Preconditions.checkArgument(angle != 0.0F && MathHelper.abs(angle) != 22.5F && MathHelper.abs(angle) != 45.0F, "Invalid rotation %f found, only -45/-22.5/0/22.5/45 allowed", angle);
+                this.angle = angle;
+                return this;
+            }
+
+            public RotationBuilder rescale(boolean rescale) {
+                this.rescale = rescale;
+                return this;
+            }
+
+            BlockPartRotation build() {
+                return new BlockPartRotation(origin, axis, angle, rescale);
+            }
+
+            public ElementBuilder end() { return ElementBuilder.this; }
+        }
+    }
+
+    public enum FaceRotation {
+        ZERO(0),
+        CLOCKWISE_90(90),
+        UPSIDE_DOWN(180),
+        COUNTERCLOCKWISE_90(270),
+        ;
+
+        final int rotation;
+
+        private FaceRotation(int rotation) {
+            this.rotation = rotation;
+        }
+    }
+
+    // Since vanilla doesn't keep the name in TransformType...
+    public enum Perspective {
+
+        THIRDPERSON_RIGHT(TransformType.THIRD_PERSON_RIGHT_HAND, "thirdperson_righthand"),
+        THIRDPERSON_LEFT(TransformType.THIRD_PERSON_LEFT_HAND, "thirdperson_lefthand"),
+        FIRSTPERSON_RIGHT(TransformType.FIRST_PERSON_RIGHT_HAND, "firstperson_righthand"),
+        FIRSTPERSON_LEFT(TransformType.FIRST_PERSON_LEFT_HAND, "firstperson_lefthand"),
+        HEAD(TransformType.HEAD, "head"),
+        GUI(TransformType.GUI, "gui"),
+        GROUND(TransformType.GROUND, "ground"),
+        FIXED(TransformType.FIXED, "fixed"),
+        ;
+
+        public final TransformType vanillaType;
+        final String name;
+
+        private Perspective(TransformType vanillaType, String name) {
+            this.vanillaType = vanillaType;
+            this.name = name;
+        }
+    }
+
+    public class TransformsBuilder {
+
+        private final Map<Perspective, TransformVecBuilder> transforms = new LinkedHashMap<>();
+
+        /**
+         * Begin building a new transform for the given perspective.
+         * 
+         * @param type the perspective to create or return the builder for
+         * @return the builder for the given perspective
+         * @throws NullPointerException if {@code type} is {@code null}
+         */
+        public TransformVecBuilder transform(Perspective type) {
+            Preconditions.checkNotNull(type, "Perspective cannot be null");
+            return transforms.computeIfAbsent(type, TransformVecBuilder::new);
+        }
+
+        Map<Perspective, ItemTransformVec3f> build() {
+            return this.transforms.entrySet().stream()
+                    .collect(Collectors.toMap(Map.Entry::getKey, e -> e.getValue().build(), (k1, k2) -> { throw new IllegalArgumentException(); }, LinkedHashMap::new));
+        }
+
+        public T end() { return self(); }
+
+        public class TransformVecBuilder {
+
+            private Vector3f rotation = new Vector3f();
+            private Vector3f translation = new Vector3f();
+            private Vector3f scale = new Vector3f();
+
+            TransformVecBuilder(Perspective type) {
+                // param unused for functional match
+            }
+
+            public TransformVecBuilder rotation(float x, float y, float z) {
+                this.rotation = new Vector3f(x, y, z);
+                return this;
+            }
+
+            public TransformVecBuilder translation(float x, float y, float z) {
+                this.translation = new Vector3f(x, y, z);
+                return this;
+            }
+
+            public TransformVecBuilder scale(float sc) {
+                return scale(sc, sc, sc);
+            }
+
+            public TransformVecBuilder scale(float x, float y, float z) {
+                this.scale = new Vector3f(x, y, z);
+                return this;
+            }
+
+            ItemTransformVec3f build() {
+                return new ItemTransformVec3f(rotation, translation, scale);
+            }
+
+            public TransformsBuilder end() { return TransformsBuilder.this; }
+        }
+    }
+}

src/main/java/net/minecraftforge/client/model/generators/ModelFile.java

@@ -0,0 +1,90 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2019.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.client.model.generators;
+
+import com.google.common.base.Preconditions;
+
+import net.minecraft.resources.ResourcePackType;
+import net.minecraft.util.ResourceLocation;
+
+public abstract class ModelFile {
+
+    protected ResourceLocation location;
+
+    protected ModelFile(ResourceLocation location) {
+        this.location = location;
+    }
+
+    protected abstract boolean exists();
+
+    public ResourceLocation getLocation() {
+        assertExistence();
+        return location;
+    }
+
+    /**
+     * Assert that this model exists.
+     * @throws IllegalStateException if this model does not exist
+     */
+    public void assertExistence() {
+        Preconditions.checkState(exists(), "Model at %s does not exist", location);
+    }
+
+    public ResourceLocation getUncheckedLocation() {
+        return location;
+    }
+
+    public static class UncheckedModelFile extends ModelFile {
+
+        public UncheckedModelFile(String location) {
+           this(new ResourceLocation(location));
+        }
+        public UncheckedModelFile(ResourceLocation location) {
+            super(location);
+        }
+
+        @Override
+        protected boolean exists() {
+            return true;
+        }
+    }
+
+    public static class ExistingModelFile extends ModelFile {
+        private final ExistingFileHelper existingHelper;
+
+        @Deprecated
+        public ExistingModelFile(String location, ExistingFileHelper existingHelper) {
+            this(new ResourceLocation(location), existingHelper);
+        }
+
+        public ExistingModelFile(ResourceLocation location, ExistingFileHelper existingHelper) {
+            super(location);
+            this.existingHelper = existingHelper;
+        }
+
+        @Override
+        protected boolean exists() {
+            if (getUncheckedLocation().getPath().contains("."))
+                return existingHelper.exists(getUncheckedLocation(), ResourcePackType.CLIENT_RESOURCES, "", "models");
+            else
+                return existingHelper.exists(getUncheckedLocation(), ResourcePackType.CLIENT_RESOURCES, ".json", "models");
+        }
+    }
+}

src/main/java/net/minecraftforge/client/model/generators/ModelProvider.java

@@ -0,0 +1,380 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2019.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.client.model.generators;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.BiFunction;
+import java.util.function.Function;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+
+import net.minecraft.data.DataGenerator;
+import net.minecraft.data.DirectoryCache;
+import net.minecraft.data.IDataProvider;
+import net.minecraft.resources.ResourcePackType;
+import net.minecraft.util.ResourceLocation;
+
+public abstract class ModelProvider<T extends ModelBuilder<T>> implements IDataProvider {
+
+    private class ExistingFileHelperIncludingGenerated extends ExistingFileHelper {
+
+        private final ExistingFileHelper delegate;
+
+        public ExistingFileHelperIncludingGenerated(ExistingFileHelper delegate) {
+            super(Collections.emptyList(), true);
+            this.delegate = delegate;
+        }
+
+        @Override
+        public boolean exists(ResourceLocation loc, ResourcePackType type, String pathSuffix, String pathPrefix) {
+            if (generatedModels.containsKey(loc)) {
+                return true;
+            }
+            return delegate.exists(loc, type, pathSuffix, pathPrefix);
+        }
+    }
+
+    public static final String BLOCK_FOLDER = "block";
+    public static final String ITEM_FOLDER = "item";
+
+    private static final Gson GSON = (new GsonBuilder()).setPrettyPrinting().create();
+    protected final DataGenerator generator;
+    protected final String modid;
+    protected final String folder;
+    protected final Function<ResourceLocation, T> factory;
+    @VisibleForTesting
+    protected final Map<ResourceLocation, T> generatedModels = new HashMap<>();
+    protected final ExistingFileHelper existingFileHelper;
+
+    protected DirectoryCache cache;
+
+    protected abstract void registerModels();
+
+    public ModelProvider(DataGenerator generator, String modid, String folder, Function<ResourceLocation, T> factory, ExistingFileHelper existingFileHelper) {
+        Preconditions.checkNotNull(generator);
+        this.generator = generator;
+        Preconditions.checkNotNull(modid);
+        this.modid = modid;
+        Preconditions.checkNotNull(folder);
+        this.folder = folder;
+        Preconditions.checkNotNull(factory);
+        this.factory = factory;
+        Preconditions.checkNotNull(existingFileHelper);
+        this.existingFileHelper = new ExistingFileHelperIncludingGenerated(existingFileHelper);
+    }
+
+    public ModelProvider(DataGenerator generator, String modid, String folder, BiFunction<ResourceLocation, ExistingFileHelper, T> builderFromModId, ExistingFileHelper existingFileHelper) {
+        this(generator, modid, folder, loc->builderFromModId.apply(loc, existingFileHelper), existingFileHelper);
+    }
+
+    protected T getBuilder(String path) {
+        Preconditions.checkNotNull(path, "Path must not be null");
+        ResourceLocation outputLoc = extendWithFolder(path.contains(":") ? new ResourceLocation(path) : new ResourceLocation(modid, path));
+        return generatedModels.computeIfAbsent(outputLoc, factory);
+    }
+
+    private ResourceLocation extendWithFolder(ResourceLocation rl) {
+        if (rl.getPath().contains("/")) {
+            return rl;
+        }
+        return new ResourceLocation(rl.getNamespace(), folder + "/" + rl.getPath());
+    }
+
+    protected ResourceLocation modLoc(String name) {
+        return new ResourceLocation(modid, name);
+    }
+
+    protected ResourceLocation mcLoc(String name) {
+        return new ResourceLocation(name);
+    }
+
+    protected T withExistingParent(String name, String parent) {
+        return withExistingParent(name, mcLoc(parent));
+    }
+
+    protected T withExistingParent(String name, ResourceLocation parent) {
+        return getBuilder(name).parent(getExistingFile(parent));
+    }
+
+    protected T cube(String name, ResourceLocation down, ResourceLocation up, ResourceLocation north, ResourceLocation south, ResourceLocation east, ResourceLocation west) {
+        return withExistingParent(name, "cube")
+                .texture("down", down)
+                .texture("up", up)
+                .texture("north", north)
+                .texture("south", south)
+                .texture("east", east)
+                .texture("west", west);
+    }
+
+    private T singleTexture(String name, String parent, ResourceLocation texture) {
+        return singleTexture(name, mcLoc(parent), texture);
+    }
+
+    protected T singleTexture(String name, ResourceLocation parent, ResourceLocation texture) {
+        return singleTexture(name, parent, "texture", texture);
+    }
+
+    private T singleTexture(String name, String parent, String textureKey, ResourceLocation texture) {
+        return singleTexture(name, mcLoc(parent), textureKey, texture);
+    }
+
+    protected T singleTexture(String name, ResourceLocation parent, String textureKey, ResourceLocation texture) {
+        return withExistingParent(name, parent)
+                .texture(textureKey, texture);
+    }
+
+    protected T cubeAll(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/cube_all", "all", texture);
+    }
+
+    protected T cubeTop(String name, ResourceLocation side, ResourceLocation top) {
+        return withExistingParent(name, BLOCK_FOLDER + "/cube_top")
+                .texture("side", side)
+                .texture("top", top);
+    }
+
+    private T sideBottomTop(String name, String parent, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        return withExistingParent(name, parent)
+                .texture("side", side)
+                .texture("bottom", bottom)
+                .texture("top", top);
+    }
+
+    protected T cubeBottomTop(String name, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        return sideBottomTop(name, BLOCK_FOLDER + "/cube_bottom_top", side, bottom, top);
+    }
+
+    protected T cubeColumn(String name, ResourceLocation side, ResourceLocation end) {
+        return withExistingParent(name, BLOCK_FOLDER + "/cube_column")
+                .texture("side", side)
+                .texture("end", end);
+    }
+
+    protected T orientableVertical(String name, ResourceLocation side, ResourceLocation front) {
+        return withExistingParent(name, BLOCK_FOLDER + "/orientable_vertical")
+                .texture("side", side)
+                .texture("front", front);
+    }
+
+    protected T orientableWithBottom(String name, ResourceLocation side, ResourceLocation front, ResourceLocation bottom, ResourceLocation top) {
+        return withExistingParent(name, BLOCK_FOLDER + "/orientable_with_bottom")
+                .texture("side", side)
+                .texture("front", front)
+                .texture("bottom", bottom)
+                .texture("top", top);
+    }
+
+    protected T orientable(String name, ResourceLocation side, ResourceLocation front, ResourceLocation top) {
+        return withExistingParent(name, BLOCK_FOLDER + "/orientable")
+                .texture("side", side)
+                .texture("front", front)
+                .texture("top", top);
+    }
+
+    protected T crop(String name, ResourceLocation crop) {
+        return singleTexture(name, BLOCK_FOLDER + "/crop", "crop", crop);
+    }
+
+    protected T cross(String name, ResourceLocation cross) {
+        return singleTexture(name, BLOCK_FOLDER + "/cross", "cross", cross);
+    }
+
+    protected T stairs(String name, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        return sideBottomTop(name, BLOCK_FOLDER + "/stairs", side, bottom, top);
+    }
+
+    protected T stairsOuter(String name, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        return sideBottomTop(name, BLOCK_FOLDER + "/outer_stairs", side, bottom, top);
+    }
+
+    protected T stairsInner(String name, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        return sideBottomTop(name, BLOCK_FOLDER + "/inner_stairs", side, bottom, top);
+    }
+
+    protected T slab(String name, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        return sideBottomTop(name, BLOCK_FOLDER + "/slab", side, bottom, top);
+    }
+
+    protected T slabTop(String name, ResourceLocation side, ResourceLocation bottom, ResourceLocation top) {
+        return sideBottomTop(name, BLOCK_FOLDER + "/slab_top", side, bottom, top);
+    }
+
+    protected T fencePost(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/fence_post", texture);
+    }
+
+    protected T fenceSide(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/fence_side", texture);
+    }
+
+    protected T fenceInventory(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/fence_inventory", texture);
+    }
+
+    protected T fenceGate(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_fence_gate", texture);
+    }
+
+    protected T fenceGateOpen(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_fence_gate_open", texture);
+    }
+
+    protected T fenceGateWall(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_fence_gate_wall", texture);
+    }
+
+    protected T fenceGateWallOpen(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_fence_gate_wall_open", texture);
+    }
+
+    protected T wallPost(String name, ResourceLocation wall) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_wall_post", "wall", wall);
+    }
+
+    protected T wallSide(String name, ResourceLocation wall) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_wall_side", "wall", wall);
+    }
+
+    protected T wallInventory(String name, ResourceLocation wall) {
+        return singleTexture(name, BLOCK_FOLDER + "/wall_inventory", "wall", wall);
+    }
+
+    private T pane(String name, String parent, ResourceLocation pane, ResourceLocation edge) {
+        return withExistingParent(name, BLOCK_FOLDER + "/" + parent)
+                .texture("pane", pane)
+                .texture("edge", edge);
+    }
+
+    protected T panePost(String name, ResourceLocation pane, ResourceLocation edge) {
+        return pane(name, "template_glass_pane_post", pane, edge);
+    }
+
+    protected T paneSide(String name, ResourceLocation pane, ResourceLocation edge) {
+        return pane(name, "template_glass_pane_side", pane, edge);
+    }
+
+    protected T paneSideAlt(String name, ResourceLocation pane, ResourceLocation edge) {
+        return pane(name, "template_glass_pane_side_alt", pane, edge);
+    }
+
+    protected T paneNoSide(String name, ResourceLocation pane) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_glass_pane_noside", "pane", pane);
+    }
+
+    protected T paneNoSideAlt(String name, ResourceLocation pane) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_glass_pane_noside_alt", "pane", pane);
+    }
+
+    private T door(String name, String model, ResourceLocation bottom, ResourceLocation top) {
+        return withExistingParent(name, BLOCK_FOLDER + "/" + model)
+                .texture("bottom", bottom)
+                .texture("top", top);
+    }
+
+    protected T doorBottomLeft(String name, ResourceLocation bottom, ResourceLocation top) {
+        return door(name, "door_bottom", bottom, top);
+    }
+
+    protected T doorBottomRight(String name, ResourceLocation bottom, ResourceLocation top) {
+        return door(name, "door_bottom_rh", bottom, top);
+    }
+
+    protected T doorTopLeft(String name, ResourceLocation bottom, ResourceLocation top) {
+        return door(name, "door_top", bottom, top);
+    }
+
+    protected T doorTopRight(String name, ResourceLocation bottom, ResourceLocation top) {
+        return door(name, "door_top_rh", bottom, top);
+    }
+
+    protected T trapdoorBottom(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_trapdoor_bottom", texture);
+    }
+
+    protected T trapdoorTop(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_trapdoor_top", texture);
+    }
+
+    protected T trapdoorOpen(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_trapdoor_open", texture);
+    }
+
+    protected T trapdoorOrientableBottom(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_orientable_trapdoor_bottom", texture);
+    }
+
+    protected T trapdoorOrientableTop(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_orientable_trapdoor_top", texture);
+    }
+
+    protected T trapdoorOrientableOpen(String name, ResourceLocation texture) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_orientable_trapdoor_open", texture);
+    }
+
+    protected T torch(String name, ResourceLocation torch) {
+        return singleTexture(name, BLOCK_FOLDER + "/template_torch", "torch", torch);
+    }
+
+    protected T torchWall(String name, ResourceLocation torch) {
+        return singleTexture(name, BLOCK_FOLDER + "/torch_wall", "torch", torch);
+    }
+
+    protected T carpet(String name, ResourceLocation wool) {
+        return singleTexture(name, BLOCK_FOLDER + "/carpet", "wool", wool);
+    }
+
+    protected ModelFile.ExistingModelFile getExistingFile(ResourceLocation path) {
+        ModelFile.ExistingModelFile ret = new ModelFile.ExistingModelFile(extendWithFolder(path), existingFileHelper);
+        ret.assertExistence();
+        return ret;
+    }
+
+    @Override
+    public void act(DirectoryCache cache) throws IOException {
+        this.cache = cache;
+        generatedModels.clear();
+        registerModels();
+        generateAll();
+        this.cache = null;
+    }
+
+    private void generateAll() {
+        for (T model : generatedModels.values()) {
+            Path target = getPath(model);
+            try {
+                IDataProvider.save(GSON, cache, model.toJson(), target);
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+        }
+    }
+
+    private Path getPath(T model) {
+        ResourceLocation loc = model.getLocation();
+        return generator.getOutputFolder().resolve("assets/" + loc.getNamespace() + "/models/" + loc.getPath() + ".json");
+    }
+}

src/main/java/net/minecraftforge/client/model/generators/MultiPartBlockStateBuilder.java

@@ -0,0 +1,125 @@
+package net.minecraftforge.client.model.generators;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map.Entry;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.Multimap;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonObject;
+
+import net.minecraft.block.Block;
+import net.minecraft.state.IProperty;
+
+public final class MultiPartBlockStateBuilder implements IGeneratedBlockstate {
+
+    private final List<PartBuilder> parts = new ArrayList<>();
+    private final Block owner;
+
+    public MultiPartBlockStateBuilder(Block owner) {
+        this.owner = owner;
+    }
+
+    /**
+     * Creates a builder for models to assign to a {@link PartBuilder}, which when
+     * completed via {@link ConfiguredModel.Builder#addModel()} will assign the
+     * resultant set of models to the part and return it for further processing.
+     * 
+     * @return the model builder
+     * @see ConfiguredModel.Builder
+     */
+    public ConfiguredModel.Builder<PartBuilder> part() {
+        return ConfiguredModel.builder(this);
+    }
+
+    MultiPartBlockStateBuilder addPart(PartBuilder part) {
+        this.parts.add(part);
+        return this;
+    }
+
+    @Override
+    public JsonObject toJson() {
+        JsonArray variants = new JsonArray();
+        for (PartBuilder part : parts) {
+            variants.add(part.toJson());
+        }
+        JsonObject main = new JsonObject();
+        main.add("multipart", variants);
+        return main;
+    }
+
+    public class PartBuilder {
+        public BlockStateProvider.ConfiguredModelList models;
+        public boolean useOr;
+        public final Multimap<IProperty<?>, Comparable<?>> conditions = HashMultimap.create();
+
+        PartBuilder(BlockStateProvider.ConfiguredModelList models) {
+            this.models = models;
+        }
+
+        public PartBuilder useOr() {
+            this.useOr = true;
+            return this;
+        }
+
+        /**
+         * Set a condition for this part, which consists of a property and a set of
+         * valid values. Can be called multiple times for multiple different properties.
+         * 
+         * @param <T>    the type of the property value
+         * @param prop   the property
+         * @param values a set of valid values
+         * @return this builder
+         * @throws NullPointerException     if {@code prop} is {@code null}
+         * @throws NullPointerException     if {@code values} is {@code null}
+         * @throws IllegalArgumentException if {@code values} is empty
+         * @throws IllegalArgumentException if {@code prop} has already been configured
+         * @throws IllegalArgumentException if {@code prop} is not applicable to the
+         *                                  current block's state
+         */
+        @SafeVarargs
+        public final <T extends Comparable<T>> PartBuilder condition(IProperty<T> prop, T... values) {
+            Preconditions.checkNotNull(prop, "Property must not be null");
+            Preconditions.checkNotNull(values, "Value list must not be null");
+            Preconditions.checkArgument(values.length > 0, "Value list must not be empty");
+            Preconditions.checkArgument(!conditions.containsKey(prop), "Cannot set condition for property \"%s\" more than once", prop.getName());
+            Preconditions.checkArgument(canApplyTo(owner), "IProperty %s is not valid for the block %s", prop, owner);
+            this.conditions.putAll(prop, Arrays.asList(values));
+            return this;
+        }
+
+        public MultiPartBlockStateBuilder end() { return MultiPartBlockStateBuilder.this; }
+
+        JsonObject toJson() {
+            JsonObject out = new JsonObject();
+            if (!conditions.isEmpty()) {
+                JsonObject when = new JsonObject();
+                for (Entry<IProperty<?>, Collection<Comparable<?>>> e : conditions.asMap().entrySet()) {
+                    StringBuilder activeString = new StringBuilder();
+                    for (Object val : e.getValue()) {
+                        if (activeString.length() > 0)
+                            activeString.append("|");
+                        activeString.append(val.toString());
+                    }
+                    when.addProperty(e.getKey().getName(), activeString.toString());
+                }
+                if (useOr) {
+                    JsonObject innerWhen = when;
+                    when = new JsonObject();
+                    when.add("OR", innerWhen);
+                }
+                out.add("when", when);
+            }
+            out.add("apply", models.toJSON());
+            return out;
+        }
+
+        public boolean canApplyTo(Block b) {
+            return b.getStateContainer().getProperties().containsAll(conditions.keySet());
+        }
+    }
+}

src/main/java/net/minecraftforge/client/model/generators/VariantBlockStateBuilder.java

@@ -0,0 +1,340 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2019.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.client.model.generators;
+
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Objects;
+import java.util.Set;
+import java.util.SortedMap;
+import java.util.SortedSet;
+import java.util.TreeSet;
+import java.util.function.Function;
+import java.util.function.Predicate;
+
+import javax.annotation.Nullable;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import com.google.gson.JsonObject;
+
+import net.minecraft.block.Block;
+import net.minecraft.block.BlockState;
+import net.minecraft.state.IProperty;
+import net.minecraftforge.client.model.generators.BlockStateProvider.ConfiguredModelList;
+
+/**
+ * Builder for variant-type blockstates, i.e. non-multipart blockstates. Should
+ * not be manually instantiated, instead use
+ * {@link BlockStateProvider#getVariantBuilder(Block)}.
+ * <p>
+ * Variants can either be set via
+ * {@link #setModels(PartialBlockstate, ConfiguredModel...)} or
+ * {@link #addModels(PartialBlockstate, ConfiguredModel...)}, where model(s) can
+ * be assigned directly to {@link PartialBlockstate partial states}, or builder
+ * style via {@link #partialState()} and its subsequent methods.
+ * <p>
+ * This class also provides the convenience methods
+ * {@link #forAllStates(Function)} and
+ * {@link #forAllStatesExcept(Function, IProperty...)} for cases where the model
+ * for each variant can be decided dynamically based on the state's property
+ * values.
+ * 
+ * @see BlockStateProvider
+ */
+public class VariantBlockStateBuilder implements IGeneratedBlockstate {
+
+    private final Block owner;
+    private final Map<PartialBlockstate, ConfiguredModelList> models = new LinkedHashMap<>();
+    private final Set<BlockState> coveredStates = new HashSet<>();
+
+    VariantBlockStateBuilder(Block owner) {
+        this.owner = owner;
+    }
+
+    public Map<PartialBlockstate, ConfiguredModelList> getModels() {
+        return models;
+    }
+
+    public Block getOwner() {
+        return owner;
+    }
+
+    @Override
+    public JsonObject toJson() {
+        List<BlockState> missingStates = Lists.newArrayList(owner.getStateContainer().getValidStates());
+        missingStates.removeAll(coveredStates);
+        Preconditions.checkState(missingStates.isEmpty(), "Blockstate for block %s does not cover all states. Missing: %s", owner, missingStates);
+        JsonObject variants = new JsonObject();
+        getModels().entrySet().stream()
+            .sorted(Entry.comparingByKey(PartialBlockstate.comparingByProperties()))
+            .forEach(entry -> variants.add(entry.getKey().toString(), entry.getValue().toJSON()));
+        JsonObject main = new JsonObject();
+        main.add("variants", variants);
+        return main;
+    }
+
+    /**
+     * Assign some models to a given {@link PartialBlockstate partial state}.
+     * 
+     * @param state  The {@link PartialBlockstate partial state} for which to add
+     *               the models
+     * @param models A set of models to add to this state
+     * @return this builder
+     * @throws NullPointerException     if {@code state} is {@code null}
+     * @throws IllegalArgumentException if {@code models} is empty
+     * @throws IllegalArgumentException if {@code state}'s owning block differs from
+     *                                  the builder's
+     * @throws IllegalArgumentException if {@code state} partially matches another
+     *                                  state which has already been configured
+     */
+    public VariantBlockStateBuilder addModels(PartialBlockstate state, ConfiguredModel... models) {
+        Preconditions.checkNotNull(state, "state must not be null");
+        Preconditions.checkArgument(models.length > 0, "Cannot set models to empty array");
+        Preconditions.checkArgument(state.getOwner() == owner, "Cannot set models for a different block. Found: %s, Current: %s", state.getOwner(), owner);
+        if (!this.models.containsKey(state)) {
+            Preconditions.checkArgument(disjointToAll(state), "Cannot set models for a state for which a partial match has already been configured");
+            this.models.put(state, new ConfiguredModelList(models));
+            for (BlockState fullState : owner.getStateContainer().getValidStates()) {
+                if (state.test(fullState)) {
+                    coveredStates.add(fullState);
+                }
+            }
+        } else {
+            this.models.compute(state, ($, cml) -> cml.append(models));
+        }
+        return this;
+    }
+
+    /**
+     * Assign some models to a given {@link PartialBlockstate partial state},
+     * throwing an exception if the state has already been configured. Otherwise,
+     * simply calls {@link #addModels(PartialBlockstate, ConfiguredModel...)}.
+     * 
+     * @param state  The {@link PartialBlockstate partial state} for which to set
+     *               the models
+     * @param models A set of models to assign to this state
+     * @return this builder
+     * @throws IllegalArgumentException if {@code state} has already been configured
+     * @see #addModels(PartialBlockstate, ConfiguredModel...)
+     */
+    public VariantBlockStateBuilder setModels(PartialBlockstate state, ConfiguredModel... model) {
+        Preconditions.checkArgument(!models.containsKey(state), "Cannot set models for a state that has already been configured: %s", state);
+        addModels(state, model);
+        return this;
+    }
+
+    private boolean disjointToAll(PartialBlockstate newState) {
+        return coveredStates.stream().noneMatch(newState);
+    }
+
+    public PartialBlockstate partialState() {
+        return new PartialBlockstate(owner, this);
+    }
+
+    public VariantBlockStateBuilder forAllStates(Function<BlockState, ConfiguredModel[]> mapper) {
+        return forAllStatesExcept(mapper);
+    }
+
+    public VariantBlockStateBuilder forAllStatesExcept(Function<BlockState, ConfiguredModel[]> mapper, IProperty<?>... ignored) {
+        Set<PartialBlockstate> seen = new HashSet<>();
+        for (BlockState fullState : owner.getStateContainer().getValidStates()) {
+            Map<IProperty<?>, Comparable<?>> propertyValues = Maps.newLinkedHashMap(fullState.getValues());
+            for (IProperty<?> p : ignored) {
+                propertyValues.remove(p);
+            }
+            PartialBlockstate partialState = new PartialBlockstate(owner, propertyValues, this);
+            if (seen.add(partialState)) {
+                setModels(partialState, mapper.apply(fullState));
+            }
+        }
+        return this;
+    }
+
+    public static class PartialBlockstate implements Predicate<BlockState> {
+        private final Block owner;
+        private final SortedMap<IProperty<?>, Comparable<?>> setStates;
+        @Nullable
+        private final VariantBlockStateBuilder outerBuilder;
+
+        PartialBlockstate(Block owner, @Nullable VariantBlockStateBuilder outerBuilder) {
+            this(owner, ImmutableMap.of(), outerBuilder);
+        }
+
+        PartialBlockstate(Block owner, Map<IProperty<?>, Comparable<?>> setStates, @Nullable VariantBlockStateBuilder outerBuilder) {
+            this.owner = owner;
+            this.outerBuilder = outerBuilder;
+            for (Map.Entry<IProperty<?>, Comparable<?>> entry : setStates.entrySet()) {
+                IProperty<?> prop = entry.getKey();
+                Comparable<?> value = entry.getValue();
+                Preconditions.checkArgument(owner.getStateContainer().getProperties().contains(prop), "Property %s not found on block %s", entry, this.owner);
+                Preconditions.checkArgument(prop.getAllowedValues().contains(value), "%s is not a valid value for %s", value, prop);
+            }
+            this.setStates = Maps.newTreeMap(Comparator.comparing(IProperty::getName));
+            this.setStates.putAll(setStates);
+        }
+
+        public <T extends Comparable<T>> PartialBlockstate with(IProperty<T> prop, T value) {
+            Preconditions.checkArgument(!setStates.containsKey(prop), "Property %s has already been set", prop);
+            Map<IProperty<?>, Comparable<?>> newState = new HashMap<>(setStates);
+            newState.put(prop, value);
+            return new PartialBlockstate(owner, newState, outerBuilder);
+        }
+
+        private void checkValidOwner() {
+            Preconditions.checkNotNull(outerBuilder, "Partial blockstate must have a valid owner to perform this action");
+        }
+
+        /**
+         * Creates a builder for models to assign to this state, which when completed
+         * via {@link ConfiguredModel.Builder#addModel()} will assign the resultant set
+         * of models to this state.
+         * 
+         * @return the model builder
+         * @see ConfiguredModel.Builder
+         */
+        public ConfiguredModel.Builder<VariantBlockStateBuilder> modelForState() {
+            checkValidOwner();
+            return ConfiguredModel.builder(outerBuilder, this);
+        }
+
+        /**
+         * Add models to the current state's variant. For use when it is more convenient
+         * to add multiple sets of models, as a replacement for
+         * {@link #setModels(ConfiguredModel...)}.
+         * 
+         * @param models The models to add.
+         * @return {@code this}
+         * @throws NullPointerException If the parent builder is {@code null}
+         */
+        public PartialBlockstate addModels(ConfiguredModel... models) {
+            checkValidOwner();
+            outerBuilder.addModels(this, models);
+            return this;
+        }
+
+        /**
+         * Set this variant's models, and return the parent builder.
+         * 
+         * @param models The models to set
+         * @return The parent builder instance
+         * @throws NullPointerException If the parent builder is {@code null}
+         */
+        public VariantBlockStateBuilder setModels(ConfiguredModel... models) {
+            checkValidOwner();
+            return outerBuilder.setModels(this, models);
+        }
+
+        /**
+         * Complete this state without adding any new models, and return a new partial
+         * state via the parent builder. For use after calling
+         * {@link #addModels(ConfiguredModel...)}.
+         * 
+         * @return A fresh partial state as specified by
+         *         {@link VariantBlockStateBuilder#partialState()}.
+         * @throws NullPointerException If the parent builder is {@code null}
+         */
+        public PartialBlockstate partialState() {
+            checkValidOwner();
+            return outerBuilder.partialState();
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            PartialBlockstate that = (PartialBlockstate) o;
+            return owner.equals(that.owner) &&
+                    setStates.equals(that.setStates);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(owner, setStates);
+        }
+
+        public Block getOwner() {
+            return owner;
+        }
+
+        public SortedMap<IProperty<?>, Comparable<?>> getSetStates() {
+            return setStates;
+        }
+
+        @Override
+        public boolean test(BlockState blockState) {
+            if (blockState.getBlock() != getOwner()) {
+                return false;
+            }
+            for (Map.Entry<IProperty<?>, Comparable<?>> entry : setStates.entrySet()) {
+                if (blockState.get(entry.getKey()) != entry.getValue()) {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        @Override
+        public String toString() {
+            StringBuilder ret = new StringBuilder();
+            for (Map.Entry<IProperty<?>, Comparable<?>> entry : setStates.entrySet()) {
+                if (ret.length() > 0) {
+                    ret.append(',');
+                }
+                ret.append(entry.getKey().getName())
+                        .append('=')
+                        .append(entry.getValue());
+            }
+            return ret.toString();
+        }
+
+        @SuppressWarnings({ "unchecked", "rawtypes" })
+        public static Comparator<PartialBlockstate> comparingByProperties() {
+            // Sort variants inversely by property values, to approximate vanilla style
+            return (s1, s2) -> {
+                SortedSet<IProperty<?>> propUniverse = new TreeSet<>(s1.getSetStates().comparator().reversed());
+                propUniverse.addAll(s1.getSetStates().keySet());
+                propUniverse.addAll(s2.getSetStates().keySet());
+                for (IProperty<?> prop : propUniverse) {
+                    Comparable val1 = s1.getSetStates().get(prop);
+                    Comparable val2 = s2.getSetStates().get(prop);
+                    if (val1 == null && val2 != null) {
+                        return -1;
+                    } else if (val2 == null && val1 != null) {
+                        return 1;
+                    } else if (val1 != null && val2 != null){
+                        int cmp = val1.compareTo(val2);
+                        if (cmp != 0) {
+                            return cmp;
+                        }
+                    }
+                }
+                return 0;
+            };
+        }
+    }
+}

src/main/java/net/minecraftforge/fml/ModLoader.java

@@ -23,6 +23,7 @@ import com.google.common.collect.ImmutableList;
 import cpw.mods.modlauncher.TransformingClassLoader;
 import net.minecraft.util.registry.Bootstrap;
 import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.client.model.generators.ExistingFileHelper;
 import net.minecraftforge.common.capabilities.CapabilityManager;
 import net.minecraftforge.eventbus.api.Event;
 import net.minecraftforge.fml.config.ConfigTracker;
@@ -103,6 +104,7 @@ public class ModLoader
     private final List<ModLoadingException> loadingExceptions;
     private final List<ModLoadingWarning> loadingWarnings;
     private GatherDataEvent.DataGeneratorConfig dataGeneratorConfig;
+    private ExistingFileHelper existingFileHelper;
     @SuppressWarnings("OptionalUsedAsFieldOrParameterType")
     private final Optional<Consumer<String>> statusConsumer = StartupMessageManager.modLoaderConsumer();
 
@@ -265,17 +267,18 @@ public class ModLoader
         this.loadingWarnings.add(warning);
     }
 
-    public void runDataGenerator(final Set<String> mods, final Path path, final Collection<Path> inputs, final boolean serverGenerators, final boolean clientGenerators, final boolean devToolGenerators, final boolean reportsGenerator, final boolean structureValidator) {
+    public void runDataGenerator(final Set<String> mods, final Path path, final Collection<Path> inputs, Collection<Path> existingPacks, final boolean serverGenerators, final boolean clientGenerators, final boolean devToolGenerators, final boolean reportsGenerator, final boolean structureValidator) {
         if (mods.contains("minecraft") && mods.size() == 1) return;
         LOGGER.info("Initializing Data Gatherer for mods {}", mods);
         Bootstrap.register();
         dataGeneratorConfig = new GatherDataEvent.DataGeneratorConfig(mods, path, inputs, serverGenerators, clientGenerators, devToolGenerators, reportsGenerator, structureValidator);
+        existingFileHelper = new ExistingFileHelper(existingPacks, structureValidator);
         gatherAndInitializeMods(null);
         dispatchAndHandleError(LifecycleEventProvider.GATHERDATA, Runnable::run, null);
         dataGeneratorConfig.runAll();
     }
 
     public Function<ModContainer, ModLifecycleEvent> getDataGeneratorEvent() {
-        return mc -> new GatherDataEvent(mc, dataGeneratorConfig.makeGenerator(p->dataGeneratorConfig.getMods().size() == 1 ? p : p.resolve(mc.getModId()), dataGeneratorConfig.getMods().contains(mc.getModId())), dataGeneratorConfig);
+        return mc -> new GatherDataEvent(mc, dataGeneratorConfig.makeGenerator(p->dataGeneratorConfig.getMods().size() == 1 ? p : p.resolve(mc.getModId()), dataGeneratorConfig.getMods().contains(mc.getModId())), dataGeneratorConfig, existingFileHelper);
     }
 }

src/main/java/net/minecraftforge/fml/event/lifecycle/GatherDataEvent.java

@@ -21,6 +21,7 @@ package net.minecraftforge.fml.event.lifecycle;
 
 import cpw.mods.modlauncher.api.LamdbaExceptionUtils;
 import net.minecraft.data.DataGenerator;
+import net.minecraftforge.client.model.generators.ExistingFileHelper;
 import net.minecraftforge.fml.ModContainer;
 
 import java.nio.file.Path;
@@ -34,14 +35,17 @@ public class GatherDataEvent extends ModLifecycleEvent
 {
     private final DataGenerator dataGenerator;
     private final DataGeneratorConfig config;
-    public GatherDataEvent(final ModContainer modContainer, final DataGenerator dataGenerator, final DataGeneratorConfig dataGeneratorConfig)
+    private final ExistingFileHelper existingFileHelper;
+    public GatherDataEvent(final ModContainer modContainer, final DataGenerator dataGenerator, final DataGeneratorConfig dataGeneratorConfig, ExistingFileHelper existingFileHelper)
     {
         super(modContainer);
         this.dataGenerator = dataGenerator;
         this.config = dataGeneratorConfig;
+        this.existingFileHelper = existingFileHelper;
     }
 
     public DataGenerator getGenerator() { return this.dataGenerator; }
+    public ExistingFileHelper getExistingFileHelper() { return existingFileHelper; }
     public boolean includeServer() { return this.config.server; }
     public boolean includeClient() { return this.config.client; }
     public boolean includeDev() { return this.config.dev; }

src/main/resources/META-INF/accesstransformer.cfg

@@ -37,7 +37,11 @@ public net.minecraft.client.renderer.model.BlockModel field_178315_d # parent
 public net.minecraft.client.renderer.model.BlockModel field_178318_c # textures
 public net.minecraft.client.renderer.model.BlockModel field_178322_i # ambientOcclusion
 public net.minecraft.client.renderer.model.BlockModel func_187966_f()Ljava/util/List; # getOverrides
+public net.minecraft.client.renderer.model.BlockPart func_178236_a(Lnet/minecraft/util/Direction;)[F # getFaceUvs
 protected net.minecraft.client.renderer.model.ItemOverrideList <init>()V
+public net.minecraft.client.renderer.model.ItemTransformVec3f$Deserializer field_178362_a # ROTATION_DEFAULT
+public net.minecraft.client.renderer.model.ItemTransformVec3f$Deserializer field_178360_b # TRANSLATION_DEFAULT
+public net.minecraft.client.renderer.model.ItemTransformVec3f$Deserializer field_178361_c # SCALE_DEFAULT
 protected net.minecraft.client.renderer.model.ModelBakery field_177598_f # resourceManager
 protected net.minecraft.client.renderer.model.ModelBakery field_177602_b # LOCATIONS_BUILTIN_TEXTURES
 public net.minecraft.client.renderer.model.ModelBakery field_177604_a # MODEL_MISSING

src/test/java/net/minecraftforge/debug/DataGeneratorTest.java

@@ -19,18 +19,72 @@
 
 package net.minecraftforge.debug;
 
+import static net.minecraftforge.debug.DataGeneratorTest.MODID;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
 import java.util.function.Consumer;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.jline.utils.InputStreamReader;
+
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Multimap;
+import com.google.common.collect.ObjectArrays;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
 
 import net.minecraft.advancements.Advancement;
 import net.minecraft.advancements.AdvancementRewards;
 import net.minecraft.advancements.FrameType;
+import net.minecraft.block.BarrelBlock;
+import net.minecraft.block.Block;
 import net.minecraft.block.Blocks;
+import net.minecraft.block.DoorBlock;
+import net.minecraft.block.FenceBlock;
+import net.minecraft.block.FenceGateBlock;
+import net.minecraft.block.FurnaceBlock;
+import net.minecraft.block.LogBlock;
+import net.minecraft.block.PaneBlock;
+import net.minecraft.block.SlabBlock;
+import net.minecraft.block.StairsBlock;
+import net.minecraft.block.TrapDoorBlock;
+import net.minecraft.block.WallBlock;
+import net.minecraft.client.renderer.model.ItemCameraTransforms;
+import net.minecraft.client.renderer.model.ItemTransformVec3f;
+import net.minecraft.client.renderer.model.Variant;
 import net.minecraft.data.DataGenerator;
+import net.minecraft.data.DirectoryCache;
 import net.minecraft.data.IFinishedRecipe;
 import net.minecraft.data.RecipeProvider;
 import net.minecraft.data.ShapedRecipeBuilder;
+import net.minecraft.resources.IResource;
+import net.minecraft.resources.ResourcePackType;
+import net.minecraft.util.Direction;
 import net.minecraft.util.ResourceLocation;
 import net.minecraft.util.text.StringTextComponent;
+import net.minecraftforge.client.model.generators.BlockStateProvider;
+import net.minecraftforge.client.model.generators.ConfiguredModel;
+import net.minecraftforge.client.model.generators.ExistingFileHelper;
+import net.minecraftforge.client.model.generators.ItemModelProvider;
+import net.minecraftforge.client.model.generators.ModelBuilder;
+import net.minecraftforge.client.model.generators.ModelBuilder.Perspective;
+import net.minecraftforge.client.model.generators.ModelFile;
+import net.minecraftforge.client.model.generators.ModelFile.UncheckedModelFile;
+import net.minecraftforge.client.model.generators.MultiPartBlockStateBuilder;
+import net.minecraftforge.client.model.generators.VariantBlockStateBuilder;
 import net.minecraftforge.common.crafting.ConditionalAdvancement;
 import net.minecraftforge.common.crafting.ConditionalRecipe;
 import net.minecraftforge.common.crafting.conditions.IConditionBuilder;
@@ -39,15 +93,29 @@ import net.minecraftforge.fml.common.Mod;
 import net.minecraftforge.fml.common.Mod.EventBusSubscriber.Bus;
 import net.minecraftforge.fml.event.lifecycle.GatherDataEvent;
 
-@Mod("data_gen_test")
+@SuppressWarnings("deprecation")
+@Mod(MODID)
 @Mod.EventBusSubscriber(bus = Bus.MOD)
 public class DataGeneratorTest
 {
+    static final String MODID = "data_gen_test";
+
+    private static final Gson GSON = new GsonBuilder()
+            .registerTypeAdapter(Variant.class, new Variant.Deserializer())
+            .registerTypeAdapter(ItemCameraTransforms.class, new ItemCameraTransforms.Deserializer())
+            .registerTypeAdapter(ItemTransformVec3f.class, new ItemTransformVec3f.Deserializer())
+            .create();
+
     @SubscribeEvent
     public static void gatherData(GatherDataEvent event)
     {
         DataGenerator gen = event.getGenerator();
 
+        if (event.includeClient())
+        {
+            gen.addProvider(new ItemModels(gen, event.getExistingFileHelper()));
+            gen.addProvider(new BlockStates(gen, event.getExistingFileHelper()));
+        }
         if (event.includeServer())
         {
             gen.addProvider(new Recipes(gen));
@@ -107,4 +175,438 @@ public class DataGeneratorTest
             .build(consumer, ID);
         }
     }
+
+    public static class ItemModels extends ItemModelProvider
+    {
+        private static final Logger LOGGER = LogManager.getLogger();
+
+        public ItemModels(DataGenerator generator, ExistingFileHelper existingFileHelper)
+        {
+            super(generator, MODID, existingFileHelper);
+        }
+
+        @Override
+        protected void registerModels()
+        {
+            getBuilder("test_generated_model")
+                    .parent(new UncheckedModelFile("item/generated"))
+                    .texture("layer0", mcLoc("block/stone"));
+
+            getBuilder("test_block_model")
+                    .parent(getExistingFile(mcLoc("block/block")))
+                    .texture("all", mcLoc("block/dirt"))
+                    .texture("top", mcLoc("block/stone"))
+                    .element()
+                        .cube("#all")
+                        .face(Direction.UP)
+                            .texture("#top")
+                            .tintindex(0)
+                            .end()
+                        .end();
+
+            // Testing consistency
+
+            // Test overrides
+            ModelFile fishingRod = withExistingParent("fishing_rod", "handheld_rod")
+                .texture("layer0", mcLoc("item/fishing_rod"))
+                .override()
+                    .predicate(mcLoc("cast"), 1)
+                    .model(getExistingFile(mcLoc("item/fishing_rod_cast"))) // Use the vanilla model for validation
+                    .end();
+
+            withExistingParent("fishing_rod_cast", modLoc("fishing_rod"))
+                .parent(fishingRod)
+                .texture("layer0", mcLoc("item/fishing_rod_cast"));
+        }
+
+        private static final Set<String> IGNORED_MODELS = ImmutableSet.of("test_generated_model", "test_block_model");
+
+        @Override
+        public void act(DirectoryCache cache) throws IOException
+        {
+            super.act(cache);
+            List<String> errors = testModelResults(this.generatedModels, existingFileHelper, IGNORED_MODELS.stream().map(s -> new ResourceLocation(MODID, folder + "/" + s)).collect(Collectors.toSet()));
+            if (!errors.isEmpty()) {
+                LOGGER.error("Found {} discrepancies between generated and vanilla item models: ", errors.size());
+                for (String s : errors) {
+                    LOGGER.error("    {}", s);
+                }
+                throw new AssertionError("Generated item models differed from vanilla equivalents, check above errors.");
+            }
+        }
+
+        @Override
+        public String getName()
+        {
+            return "Forge Test Item Models";
+        }
+    }
+
+    public static class BlockStates extends BlockStateProvider
+    {
+        private static final Logger LOGGER = LogManager.getLogger();
+
+        public BlockStates(DataGenerator gen, ExistingFileHelper exFileHelper)
+        {
+            super(gen, MODID, exFileHelper);
+        }
+
+        @Override
+        protected void registerStatesAndModels()
+        {
+            // Unnecessarily complicated example to showcase how manual building works
+            ModelFile birchFenceGate = fenceGate("birch_fence_gate", mcLoc("block/birch_planks"));
+            ModelFile birchFenceGateOpen = fenceGateOpen("birch_fence_gate_open", mcLoc("block/birch_planks"));
+            ModelFile birchFenceGateWall = fenceGateWall("birch_fence_gate_wall", mcLoc("block/birch_planks"));
+            ModelFile birchFenceGateWallOpen = fenceGateWallOpen("birch_fence_gate_wall_open", mcLoc("block/birch_planks"));
+            ModelFile invisbleModel = new UncheckedModelFile(new ResourceLocation("builtin/generated"));
+            VariantBlockStateBuilder builder = getVariantBuilder(Blocks.BIRCH_FENCE_GATE);
+            for (Direction dir : FenceGateBlock.HORIZONTAL_FACING.getAllowedValues()) {
+                int angle = (int) dir.getHorizontalAngle();
+                builder
+                    .partialState()
+                        .with(FenceGateBlock.HORIZONTAL_FACING, dir)
+                        .with(FenceGateBlock.IN_WALL, false)
+                        .with(FenceGateBlock.OPEN, false)
+                        .modelForState()
+                            .modelFile(invisbleModel)
+                        .nextModel()
+                            .modelFile(birchFenceGate)
+                            .rotationY(angle)
+                            .uvLock(true)
+                            .weight(100)
+                        .addModel()
+                    .partialState()
+                        .with(FenceGateBlock.HORIZONTAL_FACING, dir)
+                        .with(FenceGateBlock.IN_WALL, false)
+                        .with(FenceGateBlock.OPEN, true)
+                        .modelForState()
+                            .modelFile(birchFenceGateOpen)
+                            .rotationY(angle)
+                            .uvLock(true)
+                        .addModel()
+                    .partialState()
+                        .with(FenceGateBlock.HORIZONTAL_FACING, dir)
+                        .with(FenceGateBlock.IN_WALL, true)
+                        .with(FenceGateBlock.OPEN, false)
+                        .modelForState()
+                            .modelFile(birchFenceGateWall)
+                            .rotationY(angle)
+                            .uvLock(true)
+                        .addModel()
+                    .partialState()
+                        .with(FenceGateBlock.HORIZONTAL_FACING, dir)
+                        .with(FenceGateBlock.IN_WALL, true)
+                        .with(FenceGateBlock.OPEN, true)
+                        .modelForState()
+                            .modelFile(birchFenceGateWallOpen)
+                            .rotationY(angle)
+                            .uvLock(true)
+                        .addModel();
+            }
+
+            // Realistic examples using helpers
+            simpleBlock(Blocks.STONE, model -> ObjectArrays.concat(
+                    ConfiguredModel.allYRotations(model, 0, false),
+                    ConfiguredModel.allYRotations(model, 180, false),
+                    ConfiguredModel.class));
+
+            // From here on, models are 1-to-1 copies of vanilla (except for model locations) and will be tested as such below
+            ModelFile block = getBuilder("block").transforms()
+                    .transform(Perspective.GUI)
+                        .rotation(30, 225, 0)
+                        .scale(0.625f)
+                        .end()
+                    .transform(Perspective.GROUND)
+                        .translation(0, 3, 0)
+                        .scale(0.25f)
+                        .end()
+                    .transform(Perspective.FIXED)
+                        .scale(0.5f)
+                        .end()
+                    .transform(Perspective.THIRDPERSON_RIGHT)                   
+                        .rotation(75, 45, 0)
+                        .translation(0, 2.5f, 0)
+                        .scale(0.375f)
+                        .end()
+                    .transform(Perspective.FIRSTPERSON_RIGHT)
+                        .rotation(0, 45, 0)
+                        .scale(0.4f)
+                        .end()
+                    .transform(Perspective.FIRSTPERSON_LEFT)
+                        .rotation(0, 225, 0)
+                        .scale(0.4f)
+                        .end()
+                    .end();
+
+            getBuilder("cube")
+                .parent(block)
+                .element()
+                    .allFaces((dir, face) -> face.texture("#" + dir.getName()).cullface(dir));
+
+            ModelFile furnace = orientable("furnace", mcLoc("block/furnace_side"), mcLoc("block/furnace_front"), mcLoc("block/furnace_top"));
+            ModelFile furnaceLit = orientable("furnace_on", mcLoc("block/furnace_side"), mcLoc("block/furnace_front_on"), mcLoc("block/furnace_top"));
+
+            getVariantBuilder(Blocks.FURNACE)
+                .forAllStates(state -> ConfiguredModel.builder()
+                        .modelFile(state.get(FurnaceBlock.LIT) ? furnaceLit : furnace)
+                        .rotationY((int) state.get(FurnaceBlock.FACING).getOpposite().getHorizontalAngle())
+                        .build()
+                );
+
+            ModelFile barrel = cubeBottomTop("barrel", mcLoc("block/barrel_side"), mcLoc("block/barrel_bottom"), mcLoc("block/barrel_top"));
+            ModelFile barrelOpen = cubeBottomTop("barrel_open", mcLoc("block/barrel_side"), mcLoc("block/barrel_bottom"), mcLoc("block/barrel_top_open"));
+            directionalBlock(Blocks.BARREL, state -> state.get(BarrelBlock.PROPERTY_OPEN) ? barrelOpen : barrel); // Testing custom state interpreter
+
+            logBlock((LogBlock) Blocks.ACACIA_LOG);
+
+            stairsBlock((StairsBlock) Blocks.ACACIA_STAIRS, "acacia", mcLoc("block/acacia_planks"));
+            slabBlock((SlabBlock) Blocks.ACACIA_SLAB, Blocks.ACACIA_PLANKS.getRegistryName(), mcLoc("block/acacia_planks"));
+
+            fenceBlock((FenceBlock) Blocks.ACACIA_FENCE, "acacia", mcLoc("block/acacia_planks"));
+            fenceGateBlock((FenceGateBlock) Blocks.ACACIA_FENCE_GATE, "acacia", mcLoc("block/acacia_planks"));
+
+            wallBlock((WallBlock) Blocks.COBBLESTONE_WALL, "cobblestone", mcLoc("block/cobblestone"));
+
+            paneBlock((PaneBlock) Blocks.GLASS_PANE, "glass", mcLoc("block/glass"), mcLoc("block/glass_pane_top"));
+
+            doorBlock((DoorBlock) Blocks.ACACIA_DOOR, "acacia", mcLoc("block/acacia_door_bottom"), mcLoc("block/acacia_door_top"));
+            trapdoorBlock((TrapDoorBlock) Blocks.ACACIA_TRAPDOOR, "acacia", mcLoc("block/acacia_trapdoor"), true);
+            trapdoorBlock((TrapDoorBlock) Blocks.OAK_TRAPDOOR, "oak", mcLoc("block/oak_trapdoor"), false); // Test a non-orientable trapdoor
+
+            simpleBlock(Blocks.TORCH, torch("torch", mcLoc("block/torch")));
+            horizontalBlock(Blocks.WALL_TORCH, torchWall("wall_torch", mcLoc("block/torch")), 90);
+        }
+
+        // Testing the outputs
+
+        private static final Set<Block> IGNORED_BLOCKS = ImmutableSet.of(Blocks.BIRCH_FENCE_GATE, Blocks.STONE);
+        private static final Set<ResourceLocation> IGNORED_MODELS = ImmutableSet.of();
+
+        private List<String> errors = new ArrayList<>();
+
+        @Override
+        public void act(DirectoryCache cache) throws IOException
+        {
+            super.act(cache);
+            this.errors.addAll(testModelResults(this.generatedModels, existingFileHelper, IGNORED_MODELS));
+            this.registeredBlocks.forEach((block, state) -> {
+                if (IGNORED_BLOCKS.contains(block)) return;
+                JsonObject generated = state.toJson();
+                try {
+                    IResource vanillaResource = existingFileHelper.getResource(block.getRegistryName(), ResourcePackType.CLIENT_RESOURCES, ".json", "blockstates");
+                    JsonObject existing = GSON.fromJson(new InputStreamReader(vanillaResource.getInputStream()), JsonObject.class);
+                    if (state instanceof VariantBlockStateBuilder) {
+                        compareVariantBlockstates(block, generated, existing);
+                    } else if (state instanceof MultiPartBlockStateBuilder) {
+                        compareMultipartBlockstates(block, generated, existing);
+                    } else {
+                        throw new IllegalStateException("Unknown blockstate type: " + state.getClass());
+                    }
+                } catch (IOException e) {
+                    throw new RuntimeException(e);
+                }
+            });
+
+            if (!errors.isEmpty()) {
+                LOGGER.error("Found {} discrepancies between generated and vanilla models/blockstates: ", errors.size());
+                for (String s : errors) {
+                    LOGGER.error("    {}", s);
+                }
+                throw new AssertionError("Generated blockstates/models differed from vanilla equivalents, check above errors.");
+            }
+        }
+
+        private void compareVariantBlockstates(Block block, JsonObject generated, JsonObject vanilla) {
+            JsonObject generatedVariants = generated.getAsJsonObject("variants");
+            JsonObject vanillaVariants = vanilla.getAsJsonObject("variants");
+            Stream.concat(generatedVariants.entrySet().stream(), vanillaVariants.entrySet().stream())
+                .map(e -> e.getKey())
+                .distinct()
+                .forEach(key -> {
+                    JsonElement generatedVariant = generatedVariants.get(key);
+                    JsonElement vanillaVariant = vanillaVariants.get(key);
+                    if (generatedVariant.isJsonArray()) {
+                        compareArrays(block, "key " + key, "random variants", generatedVariant, vanillaVariant);
+                        for (int i = 0; i < generatedVariant.getAsJsonArray().size(); i++) {
+                            compareVariant(block, key + "[" + i + "]", generatedVariant.getAsJsonArray().get(i).getAsJsonObject(), vanillaVariant.getAsJsonArray().get(i).getAsJsonObject());
+                        }
+                    }
+                    if (generatedVariant.isJsonObject()) {
+                        if (!vanillaVariant.isJsonObject()) {
+                            blockstateError(block, "incorrectly does not have an array of variants for key %s", key);
+                            return;
+                        }
+                        compareVariant(block, key, generatedVariant.getAsJsonObject(), vanillaVariant.getAsJsonObject());
+                    }
+                });
+        }
+
+        private void compareVariant(Block block, String key, JsonObject generatedVariant, JsonObject vanillaVariant) {
+            if (generatedVariant == null) {
+                blockstateError(block, "missing variant for %s", key);
+                return;
+            }
+            if (vanillaVariant == null) {
+                blockstateError(block, "has extra variant %s", key);
+                return;
+            }
+            String generatedModel = toVanillaModel(generatedVariant.get("model").getAsString());
+            String vanillaModel = vanillaVariant.get("model").getAsString();
+            if (!generatedModel.equals(vanillaModel)) {
+                blockstateError(block, "has incorrect model \"%s\" for variant %s. Expecting: %s", generatedModel, key, vanillaModel);
+                return;
+            }
+            generatedVariant.addProperty("model", generatedModel);
+            // Parse variants to objects to handle default values in vanilla jsons
+            Variant parsedGeneratedVariant = GSON.fromJson(generatedVariant, Variant.class);
+            Variant parsedVanillaVariant = GSON.fromJson(vanillaVariant, Variant.class);
+            if (!parsedGeneratedVariant.equals(parsedVanillaVariant)) {
+                blockstateError(block, "has incorrect variant %s. Expecting: %s, Found: %s", key, vanillaVariant, generatedVariant);
+                return;
+            }
+        }
+
+        private void compareMultipartBlockstates(Block block, JsonObject generated, JsonObject vanilla) {
+            JsonElement generatedPartsElement = generated.get("multipart");
+            JsonElement vanillaPartsElement = vanilla.getAsJsonArray("multipart");
+            compareArrays(block, "parts", "multipart", generatedPartsElement, vanillaPartsElement);
+            // String instead of JSON types due to inconsistent hashing
+            Multimap<String, String> generatedPartsByCondition = HashMultimap.create();
+            Multimap<String, String> vanillaPartsByCondition = HashMultimap.create();
+
+            JsonArray generatedParts = generatedPartsElement.getAsJsonArray();
+            JsonArray vanillaParts = vanillaPartsElement.getAsJsonArray();
+            for (int i = 0; i < generatedParts.size(); i++) {
+                JsonObject generatedPart = generatedParts.get(i).getAsJsonObject();
+                String generatedCondition = toEquivalentString(generatedPart.get("when"));
+                JsonElement generatedVariants = generatedPart.get("apply");
+                if (generatedVariants.isJsonObject()) {
+                    correctVariant(generatedVariants.getAsJsonObject());
+                } else if (generatedVariants.isJsonArray()) {
+                    for (int j = 0; j < generatedVariants.getAsJsonArray().size(); j++) {
+                        correctVariant(generatedVariants.getAsJsonArray().get(i).getAsJsonObject());
+                    }
+                }
+                generatedPartsByCondition.put(generatedCondition, toEquivalentString(generatedVariants));
+
+                JsonObject vanillaPart = vanillaParts.get(i).getAsJsonObject();
+                String vanillaCondition = toEquivalentString(vanillaPart.get("when"));
+                String vanillaVariants = toEquivalentString(vanillaPart.get("apply"));
+
+                vanillaPartsByCondition.put(vanillaCondition, vanillaVariants);
+            }
+
+            Stream.concat(generatedPartsByCondition.keySet().stream(), vanillaPartsByCondition.keySet().stream())
+                .distinct()
+                .forEach(cond -> {
+                    Collection<String> generatedVariants = generatedPartsByCondition.get(cond);
+                    Collection<String> vanillaVariants = vanillaPartsByCondition.get(cond);
+                    if (generatedVariants.size() != vanillaVariants.size()) {
+                        if (vanillaVariants.isEmpty()) {
+                            blockstateError(block, " has extra condition %s", cond);
+                        } else if (generatedVariants.isEmpty()) {
+                            blockstateError(block, " is missing condition %s", cond);
+                        } else {
+                            blockstateError(block, " has differing amounts of variant lists matching condition %s. Expected: %d, Found: %d", cond, vanillaVariants.size(), generatedVariants.size());
+                        }
+                        return;
+                    }
+
+                    if (!vanillaVariants.containsAll(generatedVariants) || !generatedVariants.containsAll(vanillaVariants)) {
+                        List<String> extra = new ArrayList<>(generatedVariants);
+                        extra.removeAll(vanillaVariants);
+                        List<String> missing = new ArrayList<>(vanillaVariants);
+                        missing.removeAll(generatedVariants);
+                        if (!extra.isEmpty()) {
+                            blockstateError(block, " has extra variants for condition %s: %s", cond, extra);
+                        }
+                        if (!missing.isEmpty()) {
+                            blockstateError(block, " has missing variants for condition %s: %s", cond, missing);
+                        }
+                    }
+                });
+        }
+
+        // Eliminate some formatting differences that are not meaningful
+        private String toEquivalentString(JsonElement element) {
+            return Objects.toString(element)
+                    .replaceAll("\"(true|false)\"", "$1") // Unwrap booleans in strings
+                    .replaceAll("\"(-?(?:0|[1-9]\\d*)(?:\\.\\d+)?(?:[eE][+-]?\\d+)?)\"", "$1"); // Unwrap numbers in strings, regex from https://stackoverflow.com/questions/13340717/json-numbers-regular-expression
+        }
+
+        private void correctVariant(JsonObject variant) {
+            variant.addProperty("model", toVanillaModel(variant.get("model").getAsString()));
+        }
+
+        private boolean compareArrays(Block block, String key, String name, JsonElement generated, JsonElement vanilla) {
+            if (!vanilla.isJsonArray()) {
+                blockstateError(block, "incorrectly has an array of %s for %s", name, key);
+                return false;
+            }
+            JsonArray generatedArray = generated.getAsJsonArray();
+            JsonArray vanillaArray = vanilla.getAsJsonArray();
+            if (generatedArray.size() != vanillaArray.size()) {
+                blockstateError(block, "has incorrect number of %s for %s. Expecting: %s, Found: %s", name, key, vanillaArray.size(), generatedArray.size());
+                return false;
+            }
+            return true;
+        }
+
+        private void blockstateError(Block block, String fmt, Object... args) {
+            errors.add("Generated blockstate for block " + block + " " + String.format(fmt, args));
+        }
+
+        @Override
+        public String getName() {
+            return "Forge Test Blockstates";
+        }
+    }
+
+    private static <T extends ModelBuilder<T>> List<String> testModelResults(Map<ResourceLocation, T> models, ExistingFileHelper existingFileHelper, Set<ResourceLocation> toIgnore) {
+        List<String> ret = new ArrayList<>();
+        models.forEach((loc, model) -> {
+            if (toIgnore.contains(loc)) return;
+            JsonObject generated = model.toJson();
+            if (generated.has("parent")) {
+                generated.addProperty("parent", toVanillaModel(generated.get("parent").getAsString()));
+            }
+            try {
+                IResource vanillaResource = existingFileHelper.getResource(new ResourceLocation(loc.getPath()), ResourcePackType.CLIENT_RESOURCES, ".json", "models");
+                JsonObject existing = GSON.fromJson(new InputStreamReader(vanillaResource.getInputStream()), JsonObject.class);
+
+                JsonElement generatedDisplay = generated.remove("display");
+                JsonElement vanillaDisplay = existing.remove("display");
+                if (generatedDisplay == null && vanillaDisplay != null) {
+                    ret.add("Model " + loc + " is missing transforms");
+                    return;
+                } else if (generatedDisplay != null && vanillaDisplay == null) {
+                    ret.add("Model " + loc + " has transforms when vanilla equivalent does not");
+                    return;
+                } else if (generatedDisplay != null) { // Both must be non-null
+                    ItemCameraTransforms generatedTransforms = GSON.fromJson(generatedDisplay, ItemCameraTransforms.class);
+                    ItemCameraTransforms vanillaTransforms = GSON.fromJson(vanillaDisplay, ItemCameraTransforms.class);
+                    for (Perspective type : Perspective.values()) {
+                        if (!generatedTransforms.getTransform(type.vanillaType).equals(vanillaTransforms.getTransform(type.vanillaType))) {
+                            ret.add("Model " + loc  + " has transforms that differ from vanilla equivalent for perspective " + type.name());
+                            return;
+                        }
+                    }
+                }
+
+                if (!existing.equals(generated)) {
+                    ret.add("Model " + loc + " does not match vanilla equivalent");
+                }
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+        });
+        return ret;
+    }
+
+    private static String toVanillaModel(String model) {
+        // We generate our own model jsons to test model building, but otherwise our blockstates should be identical
+        // So remove modid to match
+        return model.replaceAll("^\\w+:", "");
+    }
 }