WorldGenHelper.java

package com.progwml6.natura.library.worldgen;

import javax.annotation.Nullable;

import net.minecraft.block.Block;
import net.minecraft.block.state.IBlockState;
import net.minecraft.util.EnumFacing;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.World;

/**
 * WorldGenHelper to help find the y coordinate/blockPos
 * Credit goes to mezz.
 */
public class WorldGenHelper
{
    /**
     * Gets the position just above the top solid or liquid ground block in the world.
     * Returns null if there is no solid or liquid ground at the given x,z coordinates.
     */
    @Nullable
    public static BlockPos getGroundPos(World world, int x, int z)
    {
        final BlockPos topPos = world.getHeight(new BlockPos(x, 0, z));

        if (topPos.getY() == 0)
        {
            return null;
        }

        final BlockPos.MutableBlockPos pos = new BlockPos.MutableBlockPos(topPos);

        IBlockState blockState = world.getBlockState(pos);

        while (isTreeBlock(blockState, world, pos) || canReplace(blockState, world, pos))
        {
            pos.move(EnumFacing.DOWN);

            if (pos.getY() <= 0)
            {
                return null;
            }

            blockState = world.getBlockState(pos);
        }

        return pos.up();
    }

    public static boolean isTreeBlock(IBlockState blockState, World world, BlockPos pos)
    {
        Block block = blockState.getBlock();
        return block.isLeaves(blockState, world, pos) || block.isWood(world, pos);
    }

    public static boolean canReplace(IBlockState blockState, World world, BlockPos pos)
    {
        Block block = blockState.getBlock();
        return block.isReplaceable(world, pos) && !blockState.getMaterial().isLiquid();
    }
}