OceanMonumentLayer.java

package amidst.map.layers;

import java.util.Arrays;
import java.util.List;
import java.util.Random;

import amidst.Options;
import amidst.map.Fragment;
import amidst.map.IconLayer;
import amidst.map.MapObjectOceanMonument;
import amidst.map.MapObjectVillage;
import amidst.minecraft.Biome;
import amidst.minecraft.MinecraftUtil;

public class OceanMonumentLayer extends IconLayer {
	
	public static List<Biome> validBiomes = Arrays.asList(
		new Biome[] { 
			Biome.deepOcean, 			
			Biome.deepOceanM, // Not sure if the extended biomes count
		}
	);
	public static List<Biome> validSurroundingBiomes = Arrays.asList(
			new Biome[] { 
				Biome.ocean, 
				Biome.deepOcean, 
				Biome.frozenOcean,
				Biome.river,
				Biome.frozenRiver,
				// Not sure if the extended biomes count
				Biome.oceanM, 
				Biome.deepOceanM, 
				Biome.frozenOceanM,
				Biome.riverM,
				Biome.frozenRiverM,
			}
		);
	
	private Random random = new Random();
	
	public OceanMonumentLayer() {
	}
	
	@Override
	public boolean isVisible() {
		return Options.instance.showOceanMonuments.get();		
	}
	
	@Override
	public void generateMapObjects(Fragment frag) {
		int size = Fragment.SIZE >> 4;
		for (int x = 0; x < size; x++) {
			for (int y = 0; y < size; y++) {
				int chunkX = x + frag.getChunkX();
				int chunkY = y + frag.getChunkY();
				if (checkChunk(chunkX, chunkY)) {
					frag.addObject(new MapObjectOceanMonument(x << 4, y << 4).setParent(this));
				}
			}
		}
	}
	 
    /** puts the World Random seed to a specific state dependent on the inputs */
    public void setRandomSeed(int a, int b, int structure_magic_number)
    {
        long positionSeed = (long)a * 341873128712L + (long)b * 132897987541L + Options.instance.seed + (long)structure_magic_number;
        random.setSeed(positionSeed);
    }
	

	public boolean checkChunk(int chunkX, int chunkY) {
		
		boolean result = false;
		
		byte maxDistanceBetweenScatteredFeatures = 32;
		byte minDistanceBetweenScatteredFeatures = 5;
		int structureSize = 29;
		int structureMagicNumber = 10387313; // 10387313 is the magic salt for ocean monuments
		
		int chunkXadj = chunkX;
		int chunkYadj = chunkY;
		if (chunkXadj < 0) chunkXadj -= maxDistanceBetweenScatteredFeatures - 1;
		if (chunkYadj < 0) chunkYadj -= maxDistanceBetweenScatteredFeatures - 1;
		
		int a = chunkXadj / maxDistanceBetweenScatteredFeatures;
		int b = chunkYadj / maxDistanceBetweenScatteredFeatures;
		
		setRandomSeed(a, b, structureMagicNumber);		

		int distanceRange = maxDistanceBetweenScatteredFeatures - minDistanceBetweenScatteredFeatures;
		a *= maxDistanceBetweenScatteredFeatures;
		b *= maxDistanceBetweenScatteredFeatures;
		a += (random.nextInt(distanceRange) + random.nextInt(distanceRange)) / 2;
		b += (random.nextInt(distanceRange) + random.nextInt(distanceRange)) / 2;
		
		if ((chunkX == a) && (chunkY == b)) {

			// Note that getBiomeAt() is full-resolution biome data, while isValidBiome() is calculated using
			// quarter-resolution biome data. This is identical to how Minecraft calculates it.
			result = 
				MinecraftUtil.getBiomeAt(  chunkX * 16 + 8, chunkY * 16 + 8) == Biome.deepOcean &&
				MinecraftUtil.isValidBiome(chunkX * 16 + 8, chunkY * 16 + 8, structureSize, validSurroundingBiomes); 
		}
		return result;
	}
}