Method getHeightValue

src/main/java/net/minecraft/world/chunk/Chunk.java:178–181

Returns the value in the height map at this x, z coordinate in the chunk

(int x, int z)

     * Returns the value in the height map at this x, z coordinate in the chunk
     */
    public int getHeightValue(int x, int z)
    {
        return this.heightMap[z << 4 | x];
    }

    /**
     * Returns the topmost ExtendedBlockStorage instance for this Chunk that actually contains a block.