GroundCover.php

<?php
 
/*
 *
 *  ____            _        _   __  __ _                  __  __ ____
 * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
 * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
 * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
 * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * @author PocketMine Team
 * @link http://www.pocketmine.net/
 *
 *
 */
 
declare(strict_types=1);
 
namespace pocketmine\world\generator\populator;
 
use pocketmine\block\BlockTypeIds;
use pocketmine\block\Liquid;
use pocketmine\block\RuntimeBlockStateRegistry;
use pocketmine\utils\Random;
use pocketmine\world\biome\BiomeRegistry;
use pocketmine\world\ChunkManager;
use pocketmine\world\format\Chunk;
use function count;
use function min;
 
class GroundCover implements Populator{
 
    public function populate(ChunkManager $world, int $chunkX, int $chunkZ, Random $random) : void{
        $chunk = $world->getChunk($chunkX, $chunkZ) ?? throw new \InvalidArgumentException("Chunk $chunkX $chunkZ does not yet exist");
        $factory = RuntimeBlockStateRegistry::getInstance();
        $biomeRegistry = BiomeRegistry::getInstance();
        for($x = 0; $x < Chunk::EDGE_LENGTH; ++$x){
            for($z = 0; $z < Chunk::EDGE_LENGTH; ++$z){
                $biome = $biomeRegistry->getBiome($chunk->getBiomeId($x, 0, $z));
                $cover = $biome->getGroundCover();
                if(count($cover) > 0){
                    $diffY = 0;
                    if(!$cover[0]->isSolid()){
                        $diffY = 1;
                    }
 
                    $startY = $chunk->getHighestBlockAt($x, $z);
                    if($startY === null){
                        //ground cover is supposed to replace preexisting blocks, nothing to do if there are no blocks
                        continue;
                    }
                    for(; $startY > 0; --$startY){
                        if(!$factory->fromStateId($chunk->getBlockStateId($x, $startY, $z))->isTransparent()){
                            break;
                        }
                    }
                    $startY = min(127, $startY + $diffY);
                    $endY = $startY - count($cover);
                    for($y = $startY; $y > $endY && $y >= 0; --$y){
                        $b = $cover[$startY - $y];
                        $id = $factory->fromStateId($chunk->getBlockStateId($x, $y, $z));
                        if($id->getTypeId() === BlockTypeIds::AIR && $b->isSolid()){
                            break;
                        }
                        if($b->canBeFlowedInto() && $id instanceof Liquid){
                            continue;
                        }
 
                        $chunk->setBlockStateId($x, $y, $z, $b->getStateId());
                    }
                }
            }
        }
    }
}