Add in an event for zombie summoning. Allows for mods to control summoning behaviour, as well as custom summoned mob.

common/net/minecraftforge/event/ForgeEventFactory.java

@@ -5,7 +5,9 @@ import java.util.List;
 
 import net.minecraft.block.Block;
 import net.minecraft.entity.EntityLiving;
+import net.minecraft.entity.EntityLivingBase;
 import net.minecraft.entity.EnumCreatureType;
+import net.minecraft.entity.monster.EntityZombie;
 import net.minecraft.entity.player.EntityPlayer;
 import net.minecraft.item.ItemStack;
 import net.minecraft.world.World;
@@ -15,6 +17,7 @@ import net.minecraftforge.event.Event.Result;
 import net.minecraftforge.event.entity.living.LivingPackSizeEvent;
 import net.minecraftforge.event.entity.living.LivingSpawnEvent;
 import net.minecraftforge.event.entity.living.LivingSpawnEvent.AllowDespawn;
+import net.minecraftforge.event.entity.living.ZombieEvent.SummonAidEvent;
 import net.minecraftforge.event.entity.player.ItemTooltipEvent;
 import net.minecraftforge.event.entity.player.PlayerDestroyItemEvent;
 import net.minecraftforge.event.entity.player.PlayerEvent;
@@ -107,4 +110,11 @@ public class ForgeEventFactory
         MinecraftForge.EVENT_BUS.post(event);
         return event;
     }
+
+    public static SummonAidEvent fireZombieSummonAid(EntityZombie zombie, World world, int x, int y, int z, EntityLivingBase attacker, double summonChance)
+    {
+        SummonAidEvent summonEvent = new SummonAidEvent(zombie, world, x, y, z, attacker, summonChance);
+        MinecraftForge.EVENT_BUS.post(summonEvent);
+        return summonEvent;
+    }
 }

common/net/minecraftforge/event/entity/living/ZombieEvent.java

@@ -0,0 +1,48 @@
+package net.minecraftforge.event.entity.living;
+
+import net.minecraft.entity.Entity;
+import net.minecraft.entity.EntityLivingBase;
+import net.minecraft.entity.monster.EntityZombie;
+import net.minecraft.world.World;
+import net.minecraftforge.event.Cancelable;
+import net.minecraftforge.event.entity.EntityEvent;
+
+public class ZombieEvent extends EntityEvent {
+
+    public ZombieEvent(EntityZombie entity)
+    {
+        super(entity);
+    }
+
+    public EntityZombie getSummoner()
+    {
+        return (EntityZombie) entity;
+    }
+
+    @HasResult
+    public class SummonAidEvent extends ZombieEvent {
+        /**
+         * Populate this field to have a custom zombie instead of a normal zombie summoned
+         */
+        public EntityZombie customSummonedAid;
+        
+        public final World world;
+        public final int x;
+        public final int y;
+        public final int z;
+        public final EntityLivingBase attacker;
+        public final double summonChance;
+        
+        public SummonAidEvent(EntityZombie entity, World world, int x, int y, int z, EntityLivingBase attacker, double summonChance)
+        {
+            super(entity);
+            this.world = world;
+            this.x = x;
+            this.y = y;
+            this.z = z;
+            this.attacker = attacker;
+            this.summonChance = summonChance;
+        }
+        
+    }
+}

patches/minecraft/net/minecraft/entity/monster/EntityZombie.java.patch

@@ -1,14 +1,17 @@
 --- ../src_base/minecraft/net/minecraft/entity/monster/EntityZombie.java
 +++ ../src_work/minecraft/net/minecraft/entity/monster/EntityZombie.java
-@@ -34,6 +34,7 @@
+@@ -34,6 +34,10 @@
  import net.minecraft.util.DamageSource;
  import net.minecraft.util.MathHelper;
  import net.minecraft.world.World;
 +import net.minecraftforge.common.ForgeDummyContainer;
++import net.minecraftforge.event.Event.Result;
++import net.minecraftforge.event.ForgeEventFactory;
++import net.minecraftforge.event.entity.living.ZombieEvent.SummonAidEvent;
  
  public class EntityZombie extends EntityMob
  {
-@@ -70,7 +71,7 @@
+@@ -70,7 +74,7 @@
          this.getEntityAttribute(SharedMonsterAttributes.followRange).setAttribute(40.0D);
          this.getEntityAttribute(SharedMonsterAttributes.movementSpeed).setAttribute(0.23000000417232513D);
          this.getEntityAttribute(SharedMonsterAttributes.attackDamage).setAttribute(3.0D);
@@ -17,7 +20,52 @@
      }
  
      protected void entityInit()
-@@ -442,7 +443,7 @@
+@@ -211,13 +215,28 @@
+                 entitylivingbase = (EntityLivingBase)par1DamageSource.getEntity();
+             }
+ 
+-            if (entitylivingbase != null && this.worldObj.difficultySetting >= 3 && (double)this.rand.nextFloat() < this.getEntityAttribute(field_110186_bp).getAttributeValue())
+-            {
+-                int i = MathHelper.floor_double(this.posX);
+-                int j = MathHelper.floor_double(this.posY);
+-                int k = MathHelper.floor_double(this.posZ);
+-                EntityZombie entityzombie = new EntityZombie(this.worldObj);
+-
++            int i = MathHelper.floor_double(this.posX);
++            int j = MathHelper.floor_double(this.posY);
++            int k = MathHelper.floor_double(this.posZ);
++
++            SummonAidEvent summonAid = ForgeEventFactory.fireZombieSummonAid(this, worldObj, i, j, k, entitylivingbase, this.getEntityAttribute(field_110186_bp).getAttributeValue());
++            
++            if (summonAid.getResult() == Result.DENY)
++            {
++                return true;
++            }
++            else if (summonAid.getResult() == Result.ALLOW || entitylivingbase != null && this.worldObj.difficultySetting >= 3 && (double)this.rand.nextFloat() < this.getEntityAttribute(field_110186_bp).getAttributeValue())
++            {
++                EntityZombie entityzombie;
++                if (summonAid.customSummonedAid != null && summonAid.getResult() == Result.ALLOW)
++                {
++                    entityzombie = summonAid.customSummonedAid;
++                }
++                else
++                {
++                    entityzombie = new EntityZombie(this.worldObj);
++                }
++                
+                 for (int l = 0; l < 50; ++l)
+                 {
+                     int i1 = i + MathHelper.getRandomIntegerInRange(this.rand, 7, 40) * MathHelper.getRandomIntegerInRange(this.rand, -1, 1);
+@@ -231,7 +250,7 @@
+                         if (this.worldObj.checkNoEntityCollision(entityzombie.boundingBox) && this.worldObj.getCollidingBoundingBoxes(entityzombie, entityzombie.boundingBox).isEmpty() && !this.worldObj.isAnyLiquid(entityzombie.boundingBox))
+                         {
+                             this.worldObj.spawnEntityInWorld(entityzombie);
+-                            entityzombie.setAttackTarget(entitylivingbase);
++                            if (entitylivingbase != null) entityzombie.setAttackTarget(entitylivingbase);
+                             entityzombie.onSpawnWithEgg((EntityLivingData)null);
+                             this.getEntityAttribute(field_110186_bp).applyModifier(new AttributeModifier("Zombie reinforcement caller charge", -0.05000000074505806D, 0));
+                             entityzombie.getEntityAttribute(field_110186_bp).applyModifier(new AttributeModifier("Zombie reinforcement callee charge", -0.05000000074505806D, 0));
+@@ -442,7 +461,7 @@
  
          if (par1EntityLivingData1 == null)
          {