New event to allow mutating a baby entity based on it's parents (#3227)

patches/minecraft/net/minecraft/entity/ai/EntityAIMate.java.patch

@@ -0,0 +1,21 @@
+--- ../src-base/minecraft/net/minecraft/entity/ai/EntityAIMate.java
++++ ../src-work/minecraft/net/minecraft/entity/ai/EntityAIMate.java
+@@ -86,6 +86,18 @@
+     {
+         EntityAgeable entityageable = this.field_75390_d.func_90011_a(this.field_75391_e);
+ 
++        final net.minecraftforge.event.entity.living.BabyEntitySpawnEvent event = new net.minecraftforge.event.entity.living.BabyEntitySpawnEvent(field_75390_d, field_75391_e, entityageable);
++        final boolean cancelled = net.minecraftforge.common.MinecraftForge.EVENT_BUS.post(event);
++        entityageable = event.getChild();
++        if (cancelled) {
++            //Reset the "inLove" state for the animals
++            this.field_75390_d.func_70873_a(6000);
++            this.field_75391_e.func_70873_a(6000);
++            this.field_75390_d.func_70875_t();
++            this.field_75391_e.func_70875_t();
++            return;
++        }
++
+         if (entityageable != null)
+         {
+             EntityPlayer entityplayer = this.field_75390_d.func_146083_cb();

patches/minecraft/net/minecraft/entity/ai/EntityAIVillagerMate.java.patch

@@ -0,0 +1,19 @@
+--- ../src-base/minecraft/net/minecraft/entity/ai/EntityAIVillagerMate.java
++++ ../src-work/minecraft/net/minecraft/entity/ai/EntityAIVillagerMate.java
+@@ -113,11 +113,15 @@
+ 
+     private void func_75447_i()
+     {
+-        EntityVillager entityvillager = this.field_75450_b.func_90011_a(this.field_75451_c);
++        net.minecraft.entity.EntityAgeable entityvillager = this.field_75450_b.func_90011_a(this.field_75451_c);
+         this.field_75451_c.func_70873_a(6000);
+         this.field_75450_b.func_70873_a(6000);
+         this.field_75451_c.func_175549_o(false);
+         this.field_75450_b.func_175549_o(false);
++
++        final net.minecraftforge.event.entity.living.BabyEntitySpawnEvent event = new net.minecraftforge.event.entity.living.BabyEntitySpawnEvent(field_75450_b, field_75451_c, entityvillager);
++        if (net.minecraftforge.common.MinecraftForge.EVENT_BUS.post(event) || event.getChild() == null) { return; }
++        entityvillager = event.getChild();
+         entityvillager.func_70873_a(-24000);
+         entityvillager.func_70012_b(this.field_75450_b.field_70165_t, this.field_75450_b.field_70163_u, this.field_75450_b.field_70161_v, 0.0F, 0.0F);
+         this.field_75448_d.func_72838_d(entityvillager);

src/main/java/net/minecraftforge/event/entity/living/BabyEntitySpawnEvent.java

@@ -0,0 +1,105 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016.
+ *
+ * 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.event.entity.living;
+
+import net.minecraft.entity.EntityAgeable;
+import net.minecraft.entity.EntityLiving;
+import net.minecraft.entity.ai.EntityAIMate;
+import net.minecraft.entity.ai.EntityAIVillagerMate;
+import net.minecraft.entity.passive.EntityAnimal;
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraftforge.common.MinecraftForge;
+import net.minecraftforge.fml.common.eventhandler.Cancelable;
+import net.minecraftforge.fml.common.eventhandler.Event;
+import javax.annotation.Nullable;
+
+/**
+ * BabyEntitySpawnEvent is fired just before a baby entity is about to be spawned. <br>
+ * Parents will have disengaged their relationship. {@link @Cancelable} <br>
+ * It is possible to change the child completely by using {@link #setChild(EntityAgeable)} <br>
+ * This event is fired from {@link EntityAIMate#spawnBaby()} and {@link EntityAIVillagerMate#giveBirth()} <br>
+ * <br>
+ * {@link #parentA} contains the initiating parent entity.<br>
+ * {@link #parentB} contains the secondary parent entity.<br>
+ * {@link #causedByPlayer} contains the player responsible for the breading (if applicable).<br>
+ * {@link #child} contains the child that will be spawned.<br>
+ * <br>
+ * This event is {@link Cancelable}.<br>
+ * If this event is canceled, the child Entity is not added to the world, and the parents <br>
+ * will no longer attempt to mate.
+ * <br>
+ * This event does not have a result. {@link HasResult}<br>
+ * <br>
+ * This event is fired on the {@link MinecraftForge#EVENT_BUS}.
+ **/
+@Cancelable
+public class BabyEntitySpawnEvent extends Event
+{
+    private final EntityLiving parentA;
+    private final EntityLiving parentB;
+    private final EntityPlayer causedByPlayer;
+    private EntityAgeable child;
+
+    public BabyEntitySpawnEvent(EntityLiving parentA, EntityLiving parentB, @Nullable EntityAgeable proposedChild)
+    {
+        //causedByPlayer calculated here to simplify the patch.
+        EntityPlayer causedByPlayer = null;
+        if (parentA instanceof EntityAnimal) {
+            causedByPlayer = ((EntityAnimal)parentA).getPlayerInLove();
+        }
+
+        if (causedByPlayer == null && parentB instanceof EntityAnimal)
+        {
+            causedByPlayer = ((EntityAnimal)parentB).getPlayerInLove();
+        }
+
+        this.parentA = parentA;
+        this.parentB = parentB;
+        this.causedByPlayer = causedByPlayer;
+        this.child = proposedChild;
+    }
+
+    public EntityLiving getParentA()
+    {
+        return parentA;
+    }
+
+    public EntityLiving getParentB()
+    {
+        return parentB;
+    }
+
+    @Nullable
+    public EntityPlayer getCausedByPlayer()
+    {
+        return causedByPlayer;
+    }
+
+    @Nullable
+    public EntityAgeable getChild()
+    {
+        return child;
+    }
+
+    public void setChild(EntityAgeable proposedChild)
+    {
+        child = proposedChild;
+    }
+}

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

@@ -0,0 +1,24 @@
+package net.minecraftforge.debug;
+
+import net.minecraft.entity.passive.EntityCow;
+import net.minecraftforge.common.MinecraftForge;
+import net.minecraftforge.event.entity.living.BabyEntitySpawnEvent;
+import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.common.event.FMLPreInitializationEvent;
+import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
+
+@Mod(modid = BreedingTest.MODID, name = "BreedingTest", version = "1.0")
+public class BreedingTest
+{
+  public static final String MODID = "breedingtest";
+
+  @Mod.EventHandler
+  public void preInit(FMLPreInitializationEvent event) {
+    MinecraftForge.EVENT_BUS.register(this);
+  }
+
+  @SubscribeEvent
+  public void onBabyBorn(BabyEntitySpawnEvent event) {
+    event.setChild(new EntityCow(event.getChild().worldObj));
+  }
+}