RegionBiomeSource.java

package me.hydos.naclmon.world.gen;

import com.mojang.serialization.Codec;
import com.mojang.serialization.codecs.RecordCodecBuilder;
import me.hydos.naclmon.world.gen.noise.OpenSimplexNoise;
import me.hydos.naclmon.world.gen.noise.VoronoiNoise;
import me.hydos.naclmon.world.gen.settings.RegionSettings;
import net.fabricmc.fabric.impl.biome.MultiNoiseSamplerHooks;
import net.minecraft.core.Holder;
import net.minecraft.util.RandomSource;
import net.minecraft.world.level.biome.Biome;
import net.minecraft.world.level.biome.BiomeManager;
import net.minecraft.world.level.biome.BiomeSource;
import net.minecraft.world.level.biome.Climate;
import net.minecraft.world.level.levelgen.XoroshiroRandomSource;
import org.joml.Vector2d;
import org.joml.Vector2i;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Stream;

/**
 * What idiot at mojang thought limiting biomes to weather conditions was a good idea. Nice way to make me hack Random everywhere...
 */
public class RegionBiomeSource extends BiomeSource implements BiomeManager.NoiseBiomeSource {
    public static final Codec<RegionBiomeSource> CODEC = RecordCodecBuilder.create(instance -> instance.group(
            Codec.DOUBLE.fieldOf("scale").forGetter(generator -> generator.scale),
            Biome.CODEC.fieldOf("ocean").forGetter(generator -> generator.oceanBiome),
            RegionSettings.CODEC.listOf().fieldOf("regions").forGetter(generator -> generator.regions)
    ).apply(instance, instance.stable(RegionBiomeSource::new)));

    private final double scale;
    public final Holder<Biome> oceanBiome;
    private final List<RegionSettings> regions;
    private OpenSimplexNoise regionNoise;
    private OpenSimplexNoise commonBiomeNoise;
    private VoronoiNoise voronoiNoise;

    public RegionBiomeSource(double scale, Holder<Biome> oceanBiome, List<RegionSettings> regionSettings) {
        this.scale = scale;
        this.oceanBiome = oceanBiome;
        this.regions = regionSettings;
    }

    @Override
    protected Codec<? extends BiomeSource> codec() {
        return CODEC;
    }

    @Override
    protected Stream<Holder<Biome>> collectPossibleBiomes() {
        var biomes = new ArrayList<Holder<Biome>>();
        for (var region : regions) biomes.addAll(region.commonBiomes());
        biomes.add(oceanBiome);
        return biomes.stream();
    }

    @Override
    public Holder<Biome> getNoiseBiome(int x, int y, int z, Climate.Sampler sampler) {
        // I believe this is called on multiple Threads. In case we don't have voronoi initialized in time initialize it on other threads too
        if (voronoiNoise == null) {
            // I can either do this myself, Or I can let FabricAPI do it.
            //noinspection UnstableApiUsage
            var random = new XoroshiroRandomSource(((MultiNoiseSamplerHooks) (Object) sampler).fabric_getSeed());
            this.regionNoise = new OpenSimplexNoise(random);
            this.commonBiomeNoise = new OpenSimplexNoise(random);
            this.voronoiNoise = new VoronoiNoise(random);
        }

        var sampleResult = voronoiNoise.distanceFromNearestCellSamplePoint(new Vector2d(x / scale, z / scale));

        if (sampleResult.distance() > 0.5) return oceanBiome;
        else return pickRegionBiome(sampleResult.closestCell(), sampleResult.distance(), x, z);
    }

    private static <T> T sampleList(double positivelyBoundRandom, List<T> list) {
        return list.get((int) (list.size() * positivelyBoundRandom));
    }

    // TODO: include distance in this too for regions that are smaller like island like ones.
    private Holder<Biome> pickRegionBiome(Vector2i cellPos, double distance, int x, int z) {
        var region = sampleList(regionNoise.samplePositiveRange(cellPos.x, cellPos.y), regions);
        if (distance > region.size()) return oceanBiome;


        return sampleList(commonBiomeNoise.samplePositiveRange(x * 0.01, z * 0.01), region.commonBiomes());
    }

    @Override
    public Holder<Biome> getNoiseBiome(int x, int y, int z) {
        // I believe this is called on multiple Threads. In case we don't have voronoi initialized in time initialize it on other threads too
        if (voronoiNoise == null) throw new RuntimeException("No random available to sample noise");

        var sampleResult = voronoiNoise.distanceFromNearestCellSamplePoint(new Vector2d(x / scale, z / scale));
        if (sampleResult.distance() > 0.5) return oceanBiome;
        else return pickRegionBiome(sampleResult.closestCell(), sampleResult.distance(), x, z);
    }
}