Code/net/minecraft/world/level/biome/FixedBiomeSource.java

package net.minecraft.world.level.biome;

import com.google.common.collect.Sets;
import com.mojang.datafixers.util.Pair;
import com.mojang.serialization.MapCodec;
import java.util.Set;
import java.util.function.Predicate;
import java.util.stream.Stream;
import javax.annotation.Nullable;
import net.minecraft.core.BlockPos;
import net.minecraft.core.Holder;
import net.minecraft.util.RandomSource;
import net.minecraft.world.level.LevelReader;

public class FixedBiomeSource extends BiomeSource implements BiomeManager.NoiseBiomeSource {
    public static final MapCodec<FixedBiomeSource> CODEC = Biome.CODEC
        .fieldOf("biome")
        .xmap(FixedBiomeSource::new, p_204259_ -> p_204259_.biome)
        .stable();
    private final Holder<Biome> biome;

    public FixedBiomeSource(Holder<Biome> p_204257_) {
        this.biome = p_204257_;
    }

    @Override
    protected Stream<Holder<Biome>> collectPossibleBiomes() {
        return Stream.of(this.biome);
    }

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

    @Override
    public Holder<Biome> getNoiseBiome(int p_204265_, int p_204266_, int p_204267_, Climate.Sampler p_204268_) {
        return this.biome;
    }

    @Override
    public Holder<Biome> getNoiseBiome(int p_204261_, int p_204262_, int p_204263_) {
        return this.biome;
    }

    @Nullable
    @Override
    public Pair<BlockPos, Holder<Biome>> findBiomeHorizontal(
        int p_220640_,
        int p_220641_,
        int p_220642_,
        int p_220643_,
        int p_220644_,
        Predicate<Holder<Biome>> p_220645_,
        RandomSource p_220646_,
        boolean p_220647_,
        Climate.Sampler p_220648_
    ) {
        if (p_220645_.test(this.biome)) {
            return p_220647_
                ? Pair.of(new BlockPos(p_220640_, p_220641_, p_220642_), this.biome)
                : Pair.of(
                    new BlockPos(
                        p_220640_ - p_220643_ + p_220646_.nextInt(p_220643_ * 2 + 1),
                        p_220641_,
                        p_220642_ - p_220643_ + p_220646_.nextInt(p_220643_ * 2 + 1)
                    ),
                    this.biome
                );
        } else {
            return null;
        }
    }

    @Nullable
    @Override
    public Pair<BlockPos, Holder<Biome>> findClosestBiome3d(
        BlockPos p_220650_, int p_220651_, int p_220652_, int p_220653_, Predicate<Holder<Biome>> p_220654_, Climate.Sampler p_220655_, LevelReader p_220656_
    ) {
        return p_220654_.test(this.biome) ? Pair.of(p_220650_, this.biome) : null;
    }

    @Override
    public Set<Holder<Biome>> getBiomesWithin(int p_187038_, int p_187039_, int p_187040_, int p_187041_, Climate.Sampler p_187042_) {
        return Sets.newHashSet(Set.of(this.biome));
    }
}