Added config option to disable Forge's fix of Stair/Slab face culling.

Some vanilla resource packs exploit this issue in their custom models causing unintended rendering issues.

patches/minecraft/net/minecraft/block/BlockSlab.java.patch

@@ -1,12 +1,15 @@
 --- ../src-base/minecraft/net/minecraft/block/BlockSlab.java
 +++ ../src-work/minecraft/net/minecraft/block/BlockSlab.java
-@@ -50,6 +50,16 @@
+@@ -50,6 +50,19 @@
          return this.func_176552_j();
      }
  
 +    @Override
 +    public boolean doesSideBlockRendering(IBlockState state, IBlockAccess world, BlockPos pos, EnumFacing face)
 +    {
++        if (net.minecraftforge.common.ForgeModContainer.disableStairSlabCulling)
++            return super.doesSideBlockRendering(state, world, pos, face);
++
 +        if ( state.func_185914_p() )
 +            return true;
 +
@@ -17,7 +20,7 @@
      public IBlockState func_180642_a(World p_180642_1_, BlockPos p_180642_2_, EnumFacing p_180642_3_, float p_180642_4_, float p_180642_5_, float p_180642_6_, int p_180642_7_, EntityLivingBase p_180642_8_)
      {
          IBlockState iblockstate = super.func_180642_a(p_180642_1_, p_180642_2_, p_180642_3_, p_180642_4_, p_180642_5_, p_180642_6_, p_180642_7_, p_180642_8_).func_177226_a(field_176554_a, BlockSlab.EnumBlockHalf.BOTTOM);
-@@ -77,13 +87,14 @@
+@@ -77,13 +90,14 @@
          {
              return false;
          }

patches/minecraft/net/minecraft/block/BlockStairs.java.patch

@@ -1,12 +1,15 @@
 --- ../src-base/minecraft/net/minecraft/block/BlockStairs.java
 +++ ../src-work/minecraft/net/minecraft/block/BlockStairs.java
-@@ -445,6 +445,17 @@
+@@ -445,6 +445,20 @@
          return new BlockStateContainer(this, new IProperty[] {field_176309_a, field_176308_b, field_176310_M});
      }
  
 +    @Override
 +    public boolean doesSideBlockRendering(IBlockState state, IBlockAccess world, BlockPos pos, EnumFacing face)
 +    {
++        if (net.minecraftforge.common.ForgeModContainer.disableStairSlabCulling)
++            return super.doesSideBlockRendering(state, world, pos, face);
++
 +        if ( state.func_185914_p() )
 +            return true;
 +

src/main/java/net/minecraftforge/common/ForgeModContainer.java

@@ -72,6 +72,7 @@ import net.minecraftforge.fml.client.FMLFileResourcePack;
 import net.minecraftforge.fml.client.FMLFolderResourcePack;
 import net.minecraftforge.fml.client.event.ConfigChangedEvent.OnConfigChangedEvent;
 import net.minecraftforge.fml.common.DummyModContainer;
+import net.minecraftforge.fml.common.FMLCommonHandler;
 import net.minecraftforge.fml.common.FMLLog;
 import net.minecraftforge.fml.common.ICrashCallable;
 import net.minecraftforge.fml.common.LoadController;
@@ -105,6 +106,7 @@ public class ForgeModContainer extends DummyModContainer implements WorldAccessC
     public static boolean forgeLightPipelineEnabled = true;
     public static boolean replaceVanillaBucketModel = true;
     public static long java8Reminder = 0;
+    public static boolean disableStairSlabCulling = false; // Also known as the "DontCullStairsBecauseIUseACrappyTexturePackThatBreaksBasicBlockShapesSoICantTrustBasicBlockCulling" flag
 
     private static Configuration config;
     private static ForgeModContainer INSTANCE;
@@ -285,6 +287,12 @@ public class ForgeModContainer extends DummyModContainer implements WorldAccessC
         prop.setLanguageKey("forge.configgui.java8Reminder");
         propOrder.add(prop.getName());
 
+        prop = config.get(Configuration.CATEGORY_CLIENT, "disableStairSlabCulling", disableStairSlabCulling,
+                "Disable culling of hidden faces next to stairs and slabs. Causes extra rendering, but may fix some resource packs that exploit this vanilla mechanic.");
+        disableStairSlabCulling = prop.getBoolean(disableStairSlabCulling);
+        prop.setLanguageKey("forge.configgui.disableStairSlabCulling").setRequiresMcRestart(false);
+        propOrder.add(prop.getName());
+
         config.setCategoryPropertyOrder(CATEGORY_CLIENT, propOrder);
 
         if (config.hasChanged())
@@ -307,20 +315,32 @@ public class ForgeModContainer extends DummyModContainer implements WorldAccessC
     @SubscribeEvent
     public void onConfigChanged(OnConfigChangedEvent event)
     {
-        if (getMetadata().modId.equals(event.getModID()) && !event.isWorldRunning())
+        if (getMetadata().modId.equals(event.getModID()))
         {
-            if (Configuration.CATEGORY_GENERAL.equals(event.getConfigID()))
+            if (!event.isWorldRunning())
             {
-                syncConfig(false);
+                if (Configuration.CATEGORY_GENERAL.equals(event.getConfigID()))
+                {
+                    syncConfig(false);
+                }
+                else if ("chunkLoader".equals(event.getConfigID()))
+                {
+                    ForgeChunkManager.syncConfigDefaults();
+                    ForgeChunkManager.loadConfiguration();
+                }
+                else if (VERSION_CHECK_CAT.equals(event.getConfigID()))
+                {
+                    syncConfig(false);
+                }
             }
-            else if ("chunkLoader".equals(event.getConfigID()))
+            else
             {
-                ForgeChunkManager.syncConfigDefaults();
-                ForgeChunkManager.loadConfiguration();
-            }
-            else if (VERSION_CHECK_CAT.equals(event.getConfigID()))
-            {
-                syncConfig(false);
+                boolean tmp = config.get(Configuration.CATEGORY_CLIENT, "disableStairSlabCulling", disableStairSlabCulling).getBoolean();
+                if (disableStairSlabCulling != tmp)
+                {
+                    disableStairSlabCulling = tmp;
+                    FMLCommonHandler.instance().reloadRenderers();
+                }
             }
         }
     }

src/main/java/net/minecraftforge/fml/client/FMLClientHandler.java

@@ -1032,4 +1032,10 @@ public class FMLClientHandler implements IFMLSidedHandler
         // We can't handle many unicode points in the splash renderer
         return CharMatcher.anyOf(ALLOWED_CHARS).retainFrom(StringUtils.stripControlCodes(message));
     }
+
+    @Override
+    public void reloadRenderers()
+    {
+        this.client.renderGlobal.loadRenderers();
+    }
 }

src/main/java/net/minecraftforge/fml/common/FMLCommonHandler.java

@@ -742,4 +742,8 @@ public class FMLCommonHandler
     {
         return sidedDelegate != null ? sidedDelegate.stripSpecialChars(message) : message;
     }
+
+    public void reloadRenderers() {
+        sidedDelegate.reloadRenderers();
+    }
 }

src/main/java/net/minecraftforge/fml/common/IFMLSidedHandler.java

@@ -73,4 +73,6 @@ public interface IFMLSidedHandler
     void processWindowMessages();
 
     String stripSpecialChars(String message);
+
+    void reloadRenderers();
 }

src/main/java/net/minecraftforge/fml/server/FMLServerHandler.java

@@ -328,4 +328,10 @@ public class FMLServerHandler implements IFMLSidedHandler
     {
         return message;
     }
+
+    @Override
+    public void reloadRenderers() {
+        // NOOP
+
+    }
 }

src/main/resources/assets/forge/lang/en_US.lang

@@ -47,6 +47,8 @@ forge.configgui.stencilbits=Enable GL Stencil Bits
 forge.configgui.replaceBuckets=Use Forge's bucket model
 forge.configgui.forgeLightPipelineEnabled=Forge Light Pipeline Enabled
 forge.configgui.java8Reminder=Java 8 Reminder timestamp
+forge.configgui.disableStairSlabCulling=Disable Stair/Slab culling.
+forge.configgui.disableStairSlabCulling.tooltip=Enable this if you see through blocks touching stairs/slabs with your resource pack.
 
 forge.configgui.modID.tooltip=The mod ID that you want to define override settings for.
 forge.configgui.modID=Mod ID