Code/net/minecraft/world/level/PathNavigationRegion.java

package net.minecraft.world.level;

import com.google.common.base.Suppliers;
import java.util.List;
import java.util.function.Supplier;
import javax.annotation.Nullable;
import net.minecraft.core.BlockPos;
import net.minecraft.core.Holder;
import net.minecraft.core.SectionPos;
import net.minecraft.core.registries.Registries;
import net.minecraft.world.entity.Entity;
import net.minecraft.world.level.biome.Biome;
import net.minecraft.world.level.biome.Biomes;
import net.minecraft.world.level.block.Blocks;
import net.minecraft.world.level.block.entity.BlockEntity;
import net.minecraft.world.level.block.state.BlockState;
import net.minecraft.world.level.border.WorldBorder;
import net.minecraft.world.level.chunk.ChunkAccess;
import net.minecraft.world.level.chunk.ChunkSource;
import net.minecraft.world.level.chunk.EmptyLevelChunk;
import net.minecraft.world.level.material.FluidState;
import net.minecraft.world.level.material.Fluids;
import net.minecraft.world.phys.AABB;
import net.minecraft.world.phys.shapes.VoxelShape;

public class PathNavigationRegion implements CollisionGetter {
    protected final int centerX;
    protected final int centerZ;
    protected final ChunkAccess[][] chunks;
    protected boolean allEmpty;
    protected final Level level;
    private final Supplier<Holder<Biome>> plains;

    public PathNavigationRegion(Level p_47164_, BlockPos p_47165_, BlockPos p_47166_) {
        this.level = p_47164_;
        this.plains = Suppliers.memoize(() -> p_47164_.registryAccess().lookupOrThrow(Registries.BIOME).getOrThrow(Biomes.PLAINS));
        this.centerX = SectionPos.blockToSectionCoord(p_47165_.getX());
        this.centerZ = SectionPos.blockToSectionCoord(p_47165_.getZ());
        int i = SectionPos.blockToSectionCoord(p_47166_.getX());
        int j = SectionPos.blockToSectionCoord(p_47166_.getZ());
        this.chunks = new ChunkAccess[i - this.centerX + 1][j - this.centerZ + 1];
        ChunkSource chunksource = p_47164_.getChunkSource();
        this.allEmpty = true;

        for (int k = this.centerX; k <= i; k++) {
            for (int l = this.centerZ; l <= j; l++) {
                this.chunks[k - this.centerX][l - this.centerZ] = chunksource.getChunkNow(k, l);
            }
        }

        for (int i1 = SectionPos.blockToSectionCoord(p_47165_.getX()); i1 <= SectionPos.blockToSectionCoord(p_47166_.getX()); i1++) {
            for (int j1 = SectionPos.blockToSectionCoord(p_47165_.getZ()); j1 <= SectionPos.blockToSectionCoord(p_47166_.getZ()); j1++) {
                ChunkAccess chunkaccess = this.chunks[i1 - this.centerX][j1 - this.centerZ];
                if (chunkaccess != null && !chunkaccess.isYSpaceEmpty(p_47165_.getY(), p_47166_.getY())) {
                    this.allEmpty = false;
                    return;
                }
            }
        }
    }

    private ChunkAccess getChunk(BlockPos p_47186_) {
        return this.getChunk(SectionPos.blockToSectionCoord(p_47186_.getX()), SectionPos.blockToSectionCoord(p_47186_.getZ()));
    }

    private ChunkAccess getChunk(int p_47168_, int p_47169_) {
        int i = p_47168_ - this.centerX;
        int j = p_47169_ - this.centerZ;
        if (i >= 0 && i < this.chunks.length && j >= 0 && j < this.chunks[i].length) {
            ChunkAccess chunkaccess = this.chunks[i][j];
            return (ChunkAccess)(chunkaccess != null ? chunkaccess : new EmptyLevelChunk(this.level, new ChunkPos(p_47168_, p_47169_), this.plains.get()));
        } else {
            return new EmptyLevelChunk(this.level, new ChunkPos(p_47168_, p_47169_), this.plains.get());
        }
    }

    @Override
    public WorldBorder getWorldBorder() {
        return this.level.getWorldBorder();
    }

    @Override
    public BlockGetter getChunkForCollisions(int p_47173_, int p_47174_) {
        return this.getChunk(p_47173_, p_47174_);
    }

    @Override
    public List<VoxelShape> getEntityCollisions(@Nullable Entity p_186557_, AABB p_186558_) {
        return List.of();
    }

    @Nullable
    @Override
    public BlockEntity getBlockEntity(BlockPos p_47180_) {
        ChunkAccess chunkaccess = this.getChunk(p_47180_);
        return chunkaccess.getBlockEntity(p_47180_);
    }

    @Override
    public BlockState getBlockState(BlockPos p_47188_) {
        if (this.isOutsideBuildHeight(p_47188_)) {
            return Blocks.AIR.defaultBlockState();
        } else {
            ChunkAccess chunkaccess = this.getChunk(p_47188_);
            return chunkaccess.getBlockState(p_47188_);
        }
    }

    @Override
    public FluidState getFluidState(BlockPos p_47171_) {
        if (this.isOutsideBuildHeight(p_47171_)) {
            return Fluids.EMPTY.defaultFluidState();
        } else {
            ChunkAccess chunkaccess = this.getChunk(p_47171_);
            return chunkaccess.getFluidState(p_47171_);
        }
    }

    @Override
    public int getMinY() {
        return this.level.getMinY();
    }

    @Override
    public int getHeight() {
        return this.level.getHeight();
    }
}