LightUpdate.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\light;
 
use pocketmine\math\Facing;
use pocketmine\world\format\LightArray;
use pocketmine\world\format\SubChunk;
use pocketmine\world\utils\SubChunkExplorer;
use pocketmine\world\utils\SubChunkExplorerStatus;
use pocketmine\world\World;
use function assert;
use function max;
 
//TODO: make light updates asynchronous
abstract class LightUpdate{
    public const BASE_LIGHT_FILTER = 1;
 
    protected array $updateNodes = [];
 
    public function __construct(
        protected SubChunkExplorer $subChunkExplorer,
        protected array $lightFilters
    ){}
 
    abstract protected function getCurrentLightArray() : LightArray;
 
    abstract public function recalculateNode(int $x, int $y, int $z) : void;
 
    abstract public function recalculateChunk(int $chunkX, int $chunkZ) : int;
 
    protected function getEffectiveLight(int $x, int $y, int $z) : int{
        if($this->subChunkExplorer->moveTo($x, $y, $z) !== SubChunkExplorerStatus::INVALID){
            return $this->getCurrentLightArray()->get($x & SubChunk::COORD_MASK, $y & SubChunk::COORD_MASK, $z & SubChunk::COORD_MASK);
        }
        return 0;
    }
 
    protected function getHighestAdjacentLight(int $x, int $y, int $z) : int{
        $adjacent = 0;
        foreach(Facing::OFFSET as [$ox, $oy, $oz]){
            if(($adjacent = max($adjacent, $this->getEffectiveLight($x + $ox, $y + $oy, $z + $oz))) === 15){
                break;
            }
        }
        return $adjacent;
    }
 
    public function setAndUpdateLight(int $x, int $y, int $z, int $newLevel) : void{
        $this->updateNodes[World::blockHash($x, $y, $z)] = [$x, $y, $z, $newLevel];
    }
 
    private function prepareNodes() : LightPropagationContext{
        $context = new LightPropagationContext();
        foreach($this->updateNodes as $blockHash => [$x, $y, $z, $newLevel]){
            if($this->subChunkExplorer->moveTo($x, $y, $z) !== SubChunkExplorerStatus::INVALID){
                $lightArray = $this->getCurrentLightArray();
                $oldLevel = $lightArray->get($x & SubChunk::COORD_MASK, $y & SubChunk::COORD_MASK, $z & SubChunk::COORD_MASK);
 
                if($oldLevel !== $newLevel){
                    $lightArray->set($x & SubChunk::COORD_MASK, $y & SubChunk::COORD_MASK, $z & SubChunk::COORD_MASK, $newLevel);
                    if($oldLevel < $newLevel){ //light increased
                        $context->spreadVisited[$blockHash] = true;
                        $context->spreadQueue->enqueue([$x, $y, $z]);
                    }else{ //light removed
                        $context->removalVisited[$blockHash] = true;
                        $context->removalQueue->enqueue([$x, $y, $z, $oldLevel]);
                    }
                }
            }
        }
        return $context;
    }
 
    public function execute() : int{
        $context = $this->prepareNodes();
 
        $touched = 0;
        $lightArray = null;
        $subChunkExplorer = $this->subChunkExplorer;
        $subChunkExplorer->invalidate();
        while(!$context->removalQueue->isEmpty()){
            $touched++;
            [$x, $y, $z, $oldAdjacentLight] = $context->removalQueue->dequeue();
 
            foreach(Facing::OFFSET as [$ox, $oy, $oz]){
                $cx = $x + $ox;
                $cy = $y + $oy;
                $cz = $z + $oz;
 
                $moveStatus = $subChunkExplorer->moveTo($cx, $cy, $cz);
                if($moveStatus === SubChunkExplorerStatus::INVALID){
                    continue;
                }
                if($moveStatus === SubChunkExplorerStatus::MOVED){
                    $lightArray = $this->getCurrentLightArray();
                }
                assert($lightArray !== null);
                $this->computeRemoveLight($cx, $cy, $cz, $oldAdjacentLight, $context, $lightArray);
            }
        }
 
        $subChunk = null;
        $subChunkExplorer->invalidate();
        while(!$context->spreadQueue->isEmpty()){
            $touched++;
            [$x, $y, $z] = $context->spreadQueue->dequeue();
            $from = $context->spreadVisited[World::blockHash($x, $y, $z)];
 
            unset($context->spreadVisited[World::blockHash($x, $y, $z)]);
 
            $moveStatus = $subChunkExplorer->moveTo($x, $y, $z);
            if($moveStatus === SubChunkExplorerStatus::INVALID){
                continue;
            }
            if($moveStatus === SubChunkExplorerStatus::MOVED){
                $subChunk = $subChunkExplorer->currentSubChunk;
                $lightArray = $this->getCurrentLightArray();
            }
            assert($lightArray !== null);
 
            $newAdjacentLight = $lightArray->get($x & SubChunk::COORD_MASK, $y & SubChunk::COORD_MASK, $z & SubChunk::COORD_MASK);
            if($newAdjacentLight <= 0){
                continue;
            }
 
            foreach(Facing::OFFSET as $side => [$ox, $oy, $oz]){
                if($from === $side){
                    //don't check the side that this node received its initial light from
                    continue;
                }
                $cx = $x + $ox;
                $cy = $y + $oy;
                $cz = $z + $oz;
 
                $moveStatus = $subChunkExplorer->moveTo($cx, $cy, $cz);
                if($moveStatus === SubChunkExplorerStatus::INVALID){
                    continue;
                }
                if($moveStatus === SubChunkExplorerStatus::MOVED){
                    $subChunk = $subChunkExplorer->currentSubChunk;
                    $lightArray = $this->getCurrentLightArray();
                }
                assert($subChunk !== null);
                $this->computeSpreadLight($cx, $cy, $cz, $newAdjacentLight, $context, $lightArray, $subChunk, $side);
            }
        }
 
        return $touched;
    }
 
    protected function computeRemoveLight(int $x, int $y, int $z, int $oldAdjacentLevel, LightPropagationContext $context, LightArray $lightArray) : void{
        $lx = $x & SubChunk::COORD_MASK;
        $ly = $y & SubChunk::COORD_MASK;
        $lz = $z & SubChunk::COORD_MASK;
        $current = $lightArray->get($lx, $ly, $lz);
 
        if($current !== 0 && $current < $oldAdjacentLevel){
            $lightArray->set($lx, $ly, $lz, 0);
 
            if(!isset($context->removalVisited[$index = World::blockHash($x, $y, $z)])){
                $context->removalVisited[$index] = true;
                if($current > 1){
                    $context->removalQueue->enqueue([$x, $y, $z, $current]);
                }
            }
        }elseif($current >= $oldAdjacentLevel){
            if(!isset($context->spreadVisited[$index = World::blockHash($x, $y, $z)])){
                $context->spreadVisited[$index] = true;
                $context->spreadQueue->enqueue([$x, $y, $z]);
            }
        }
    }
 
    protected function computeSpreadLight(int $x, int $y, int $z, int $newAdjacentLevel, LightPropagationContext $context, LightArray $lightArray, SubChunk $subChunk, int $side) : void{
        $lx = $x & SubChunk::COORD_MASK;
        $ly = $y & SubChunk::COORD_MASK;
        $lz = $z & SubChunk::COORD_MASK;
        $current = $lightArray->get($lx, $ly, $lz);
        $potentialLight = $newAdjacentLevel - ($this->lightFilters[$subChunk->getBlockStateId($lx, $ly, $lz)] ?? self::BASE_LIGHT_FILTER);
 
        if($current < $potentialLight){
            $lightArray->set($lx, $ly, $lz, $potentialLight);
 
            if(!isset($context->spreadVisited[$index = World::blockHash($x, $y, $z)]) && $potentialLight > 1){
                //Track where this node was lit from, to avoid checking the source again when we propagate from here
                //TODO: In the future it might be worth tracking more than one adjacent source face in case multiple
                //nodes try to light the same node. However, this is a rare case since the vast majority of calls are
                //basic propagation with only one source anyway.
                $context->spreadVisited[$index] = Facing::opposite($side);
                $context->spreadQueue->enqueue([$x, $y, $z]);
            }
        }
    }
}