WorldEvents.java

package slimeknights.tconstruct.world;

import net.minecraft.entity.EnumCreatureType;
import net.minecraft.entity.monster.EntityMagmaCube;
import net.minecraft.world.biome.Biome;
import net.minecraftforge.event.world.WorldEvent;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;

import slimeknights.tconstruct.world.entity.EntityBlueSlime;
import slimeknights.tconstruct.world.worldgen.MagmaSlimeIslandGenerator;
import slimeknights.tconstruct.world.worldgen.SlimeIslandGenerator;

public class WorldEvents {

  // Custom slime spawning on slime islands
  Biome.SpawnListEntry magmaSlimeSpawn = new Biome.SpawnListEntry(EntityMagmaCube.class, 150, 4, 6);
  Biome.SpawnListEntry blueSlimeSpawn = new Biome.SpawnListEntry(EntityBlueSlime.class, 15, 2, 4);

  @SubscribeEvent
  public void extraSlimeSpawn(WorldEvent.PotentialSpawns event) {
    if(event.getType() == EnumCreatureType.MONSTER) {
      // inside a magma slime island?
      if(MagmaSlimeIslandGenerator.INSTANCE.isSlimeIslandAt(event.getWorld(), event.getPos().down(3))) {
        // spawn magma slime, pig zombies have weight 100
        event.getList().clear();
        event.getList().add(magmaSlimeSpawn);
      }
      // inside a slime island?
      if(SlimeIslandGenerator.INSTANCE.isSlimeIslandAt(event.getWorld(), event.getPos().down(3))) {
        // spawn blue slime, most regular mobs have weight 10
        event.getList().clear();
        event.getList().add(blueSlimeSpawn);
      }
    }
  }
}