Code/net/minecraft/world/level/levelgen/feature/FallenTreeFeature.java

package net.minecraft.world.level.levelgen.feature;

import com.mojang.serialization.Codec;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.function.BiConsumer;
import java.util.function.Function;
import net.minecraft.core.BlockPos;
import net.minecraft.core.Direction;
import net.minecraft.util.RandomSource;
import net.minecraft.world.level.LevelAccessor;
import net.minecraft.world.level.WorldGenLevel;
import net.minecraft.world.level.block.RotatedPillarBlock;
import net.minecraft.world.level.block.state.BlockState;
import net.minecraft.world.level.levelgen.feature.configurations.FallenTreeConfiguration;
import net.minecraft.world.level.levelgen.feature.treedecorators.TreeDecorator;

public class FallenTreeFeature extends Feature<FallenTreeConfiguration> {
    private static final int STUMP_HEIGHT = 1;
    private static final int STUMP_HEIGHT_PLUS_EMPTY_SPACE = 2;
    private static final int FALLEN_LOG_MAX_FALL_HEIGHT_TO_GROUND = 5;
    private static final int FALLEN_LOG_MAX_GROUND_GAP = 2;
    private static final int FALLEN_LOG_MAX_SPACE_FROM_STUMP = 2;
    private static final int BLOCK_UPDATE_FLAGS = 19;

    public FallenTreeFeature(Codec<FallenTreeConfiguration> p_392549_) {
        super(p_392549_);
    }

    @Override
    public boolean place(FeaturePlaceContext<FallenTreeConfiguration> p_393978_) {
        this.placeFallenTree(p_393978_.config(), p_393978_.origin(), p_393978_.level(), p_393978_.random());
        return true;
    }

    private void placeFallenTree(FallenTreeConfiguration p_392644_, BlockPos p_394187_, WorldGenLevel p_395647_, RandomSource p_391733_) {
        this.placeStump(p_392644_, p_395647_, p_391733_, p_394187_.mutable());
        Direction direction = Direction.Plane.HORIZONTAL.getRandomDirection(p_391733_);
        int i = p_392644_.logLength.sample(p_391733_) - 2;
        BlockPos.MutableBlockPos blockpos$mutableblockpos = p_394187_.relative(direction, 2 + p_391733_.nextInt(2)).mutable();
        this.setGroundHeightForFallenLogStartPos(p_395647_, blockpos$mutableblockpos);
        if (this.canPlaceEntireFallenLog(p_395647_, i, blockpos$mutableblockpos, direction)) {
            this.placeFallenLog(p_392644_, p_395647_, p_391733_, i, blockpos$mutableblockpos, direction);
        }
    }

    private void setGroundHeightForFallenLogStartPos(WorldGenLevel p_396419_, BlockPos.MutableBlockPos p_397012_) {
        p_397012_.move(Direction.UP, 1);

        for (int i = 0; i < 6; i++) {
            if (this.mayPlaceOn(p_396419_, p_397012_)) {
                return;
            }

            p_397012_.move(Direction.DOWN);
        }
    }

    private void placeStump(FallenTreeConfiguration p_395657_, WorldGenLevel p_396801_, RandomSource p_392489_, BlockPos.MutableBlockPos p_394715_) {
        BlockPos blockpos = this.placeLogBlock(p_395657_, p_396801_, p_392489_, p_394715_, Function.identity());
        this.decorateLogs(p_396801_, p_392489_, Set.of(blockpos), p_395657_.stumpDecorators);
    }

    private boolean canPlaceEntireFallenLog(WorldGenLevel p_394921_, int p_393137_, BlockPos.MutableBlockPos p_393745_, Direction p_393391_) {
        int i = 0;

        for (int j = 0; j < p_393137_; j++) {
            if (!TreeFeature.validTreePos(p_394921_, p_393745_)) {
                return false;
            }

            if (!this.isOverSolidGround(p_394921_, p_393745_)) {
                if (++i > 2) {
                    return false;
                }
            } else {
                i = 0;
            }

            p_393745_.move(p_393391_);
        }

        p_393745_.move(p_393391_.getOpposite(), p_393137_);
        return true;
    }

    private void placeFallenLog(
        FallenTreeConfiguration p_394838_,
        WorldGenLevel p_396397_,
        RandomSource p_394699_,
        int p_396625_,
        BlockPos.MutableBlockPos p_394037_,
        Direction p_396491_
    ) {
        Set<BlockPos> set = new HashSet<>();

        for (int i = 0; i < p_396625_; i++) {
            set.add(this.placeLogBlock(p_394838_, p_396397_, p_394699_, p_394037_, getSidewaysStateModifier(p_396491_)));
            p_394037_.move(p_396491_);
        }

        this.decorateLogs(p_396397_, p_394699_, set, p_394838_.logDecorators);
    }

    private boolean mayPlaceOn(LevelAccessor p_394406_, BlockPos p_392150_) {
        return TreeFeature.validTreePos(p_394406_, p_392150_) && this.isOverSolidGround(p_394406_, p_392150_);
    }

    private boolean isOverSolidGround(LevelAccessor p_395614_, BlockPos p_395166_) {
        return p_395614_.getBlockState(p_395166_.below()).isFaceSturdy(p_395614_, p_395166_, Direction.UP);
    }

    private BlockPos placeLogBlock(
        FallenTreeConfiguration p_395209_,
        WorldGenLevel p_394250_,
        RandomSource p_392111_,
        BlockPos.MutableBlockPos p_394770_,
        Function<BlockState, BlockState> p_397029_
    ) {
        p_394250_.setBlock(p_394770_, p_397029_.apply(p_395209_.trunkProvider.getState(p_392111_, p_394770_)), 3);
        this.markAboveForPostProcessing(p_394250_, p_394770_);
        return p_394770_.immutable();
    }

    private void decorateLogs(WorldGenLevel p_395747_, RandomSource p_396895_, Set<BlockPos> p_394439_, List<TreeDecorator> p_394258_) {
        if (!p_394258_.isEmpty()) {
            TreeDecorator.Context treedecorator$context = new TreeDecorator.Context(
                p_395747_, this.getDecorationSetter(p_395747_), p_396895_, p_394439_, Set.of(), Set.of()
            );
            p_394258_.forEach(p_393767_ -> p_393767_.place(treedecorator$context));
        }
    }

    private BiConsumer<BlockPos, BlockState> getDecorationSetter(WorldGenLevel p_392222_) {
        return (p_391644_, p_394520_) -> p_392222_.setBlock(p_391644_, p_394520_, 19);
    }

    private static Function<BlockState, BlockState> getSidewaysStateModifier(Direction p_397923_) {
        return p_391565_ -> p_391565_.trySetValue(RotatedPillarBlock.AXIS, p_397923_.getAxis());
    }
}