FeatureGenCave.java

package cofh.lib.world.feature;

import java.util.Random;

import net.minecraft.block.Block;
import net.minecraft.world.World;
import net.minecraft.world.gen.feature.WorldGenerator;

public class FeatureGenCave extends FeatureBase {

	final WorldGenerator worldGen;
	final int count;
	final boolean ceiling;

	public FeatureGenCave(String name, WorldGenerator worldGen, boolean ceiling, int count, GenRestriction biomeRes,
			boolean regen, GenRestriction dimRes) {

		super(name, biomeRes, regen, dimRes);
		this.worldGen = worldGen;
		this.count = count;
		this.ceiling = ceiling;
	}

	@Override
	protected boolean generateFeature(Random random, int chunkX, int chunkZ, World world) {

		int averageSeaLevel = world.provider.getAverageGroundLevel() + 1;
		int blockX = chunkX * 16;
		int blockZ = chunkZ * 16;


		boolean generated = false;
		for (int i = 0; i < count; i++) {
			int x = blockX + random.nextInt(16);
			int z = blockZ + random.nextInt(16);
			if (!canGenerateInBiome(world, x, z, random))
				continue;
			int seaLevel = averageSeaLevel;
			if (seaLevel < 20) {
				seaLevel = world.getHeightValue(x, z);
			}

			int stopY = random.nextInt(1 + seaLevel / 2);
			int y = stopY;
			Block block;
			do {
				block = world.getBlock(x, y, z);
			} while (!block.isAir(world, x, y, z) && ++y < seaLevel);

			if (y == seaLevel) {
				y = 0;
				do {
					block = world.getBlock(x, y, z);
				} while (!block.isAir(world, x, y, z) && ++y < stopY);
				if (y == stopY)
					continue;
			}

			if (ceiling) {
				if (y < stopY)
					seaLevel = stopY + 1;
				do {
					++y;
					block = world.getBlock(x, y, z);
				} while (y < seaLevel && block.isAir(world, x, y, z));
				if (y == seaLevel)
					continue;
				--y;
			} else if (block.isAir(world, x, y - 1, z)) {
				--y;
				do {
					block = world.getBlock(x, y, z);
				} while (block.isAir(world, x, y, z) && y --> 0);
				if (y == -1)
					continue;
				++y;
			}

			generated |= worldGen.generate(world, random, x, y, z);
		}
		return generated;
	}

}