Liquid.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\block;
 
use pocketmine\block\utils\BlockEventHelper;
use pocketmine\block\utils\MinimumCostFlowCalculator;
use pocketmine\block\utils\SupportType;
use pocketmine\data\runtime\RuntimeDataDescriber;
use pocketmine\entity\Entity;
use pocketmine\event\block\BlockSpreadEvent;
use pocketmine\item\Item;
use pocketmine\math\AxisAlignedBB;
use pocketmine\math\Facing;
use pocketmine\math\Vector3;
use pocketmine\world\sound\FizzSound;
use pocketmine\world\sound\Sound;
use function lcg_value;
 
abstract class Liquid extends Transparent{
    public const MAX_DECAY = 7;
 
    public int $adjacentSources = 0;
 
    protected ?Vector3 $flowVector = null;
 
    protected bool $falling = false;
    protected int $decay = 0; //PC "level" property
    protected bool $still = false;
 
    protected function describeBlockOnlyState(RuntimeDataDescriber $w) : void{
        $w->boundedIntAuto(0, self::MAX_DECAY, $this->decay);
        $w->bool($this->falling);
        $w->bool($this->still);
    }
 
    public function isFalling() : bool{ return $this->falling; }
 
    public function setFalling(bool $falling) : self{
        $this->falling = $falling;
        return $this;
    }
 
    public function getDecay() : int{ return $this->decay; }
 
    public function setDecay(int $decay) : self{
        if($decay < 0 || $decay > self::MAX_DECAY){
            throw new \InvalidArgumentException("Decay must be in range 0 ... " . self::MAX_DECAY);
        }
        $this->decay = $decay;
        return $this;
    }
 
    public function hasEntityCollision() : bool{
        return true;
    }
 
    public function canBeReplaced() : bool{
        return true;
    }
 
    public function canBeFlowedInto() : bool{
        return true;
    }
 
    public function isSolid() : bool{
        return false;
    }
 
    protected function recalculateCollisionBoxes() : array{
        return [];
    }
 
    public function getSupportType(int $facing) : SupportType{
        return SupportType::NONE;
    }
 
    public function getDropsForCompatibleTool(Item $item) : array{
        return [];
    }
 
    public function getStillForm() : Block{
        $b = clone $this;
        $b->still = true;
        return $b;
    }
 
    public function getFlowingForm() : Block{
        $b = clone $this;
        $b->still = false;
        return $b;
    }
 
    abstract public function getBucketFillSound() : Sound;
 
    abstract public function getBucketEmptySound() : Sound;
 
    public function isSource() : bool{
        return !$this->falling && $this->decay === 0;
    }
 
    public function getFluidHeightPercent(){
        return (($this->falling ? 0 : $this->decay) + 1) / 9;
    }
 
    public function isStill() : bool{
        return $this->still;
    }
 
    public function setStill(bool $still = true) : self{
        $this->still = $still;
        return $this;
    }
 
    protected function getEffectiveFlowDecay(Block $block) : int{
        if(!($block instanceof Liquid) || !$block->hasSameTypeId($this)){
            return -1;
        }
 
        return $block->falling ? 0 : $block->decay;
    }
 
    public function readStateFromWorld() : Block{
        parent::readStateFromWorld();
        $this->flowVector = null;
 
        return $this;
    }
 
    public function getFlowVector() : Vector3{
        if($this->flowVector !== null){
            return $this->flowVector;
        }
 
        $vX = $vY = $vZ = 0;
 
        $x = $this->position->getFloorX();
        $y = $this->position->getFloorY();
        $z = $this->position->getFloorZ();
 
        $decay = $this->getEffectiveFlowDecay($this);
 
        $world = $this->position->getWorld();
 
        foreach(Facing::HORIZONTAL as $j){
            [$dx, $dy, $dz] = Facing::OFFSET[$j];
 
            $sideX = $x + $dx;
            $sideY = $y + $dy;
            $sideZ = $z + $dz;
 
            $sideBlock = $world->getBlockAt($sideX, $sideY, $sideZ);
            $blockDecay = $this->getEffectiveFlowDecay($sideBlock);
 
            if($blockDecay < 0){
                if(!$sideBlock->canBeFlowedInto()){
                    continue;
                }
 
                $blockDecay = $this->getEffectiveFlowDecay($world->getBlockAt($sideX, $sideY - 1, $sideZ));
 
                if($blockDecay >= 0){
                    $realDecay = $blockDecay - ($decay - 8);
                    $vX += $dx * $realDecay;
                    $vY += $dy * $realDecay;
                    $vZ += $dz * $realDecay;
                }
 
                continue;
            }else{
                $realDecay = $blockDecay - $decay;
                $vX += $dx * $realDecay;
                $vY += $dy * $realDecay;
                $vZ += $dz * $realDecay;
            }
        }
 
        $vector = new Vector3($vX, $vY, $vZ);
 
        if($this->falling){
            foreach(Facing::HORIZONTAL as $facing){
                [$dx, $dy, $dz] = Facing::OFFSET[$facing];
                if(
                    !$this->canFlowInto($world->getBlockAt($x + $dx, $y + $dy, $z + $dz)) ||
                    !$this->canFlowInto($world->getBlockAt($x + $dx, $y + $dy + 1, $z + $dz))
                ){
                    $vector = $vector->normalize()->add(0, -6, 0);
                    break;
                }
            }
        }
 
        return $this->flowVector = $vector->normalize();
    }
 
    public function addVelocityToEntity(Entity $entity) : ?Vector3{
        if($entity->canBeMovedByCurrents()){
            return $this->getFlowVector();
        }
        return null;
    }
 
    abstract public function tickRate() : int;
 
    public function getFlowDecayPerBlock() : int{
        return 1;
    }
 
    public function getMinAdjacentSourcesToFormSource() : ?int{
        return null;
    }
 
    public function onNearbyBlockChange() : void{
        if(!$this->checkForHarden()){
            $this->position->getWorld()->scheduleDelayedBlockUpdate($this->position, $this->tickRate());
        }
    }
 
    public function onScheduledUpdate() : void{
        $multiplier = $this->getFlowDecayPerBlock();
 
        $world = $this->position->getWorld();
 
        $x = $this->position->getFloorX();
        $y = $this->position->getFloorY();
        $z = $this->position->getFloorZ();
 
        if(!$this->isSource()){
            $smallestFlowDecay = -100;
            $this->adjacentSources = 0;
            $smallestFlowDecay = $this->getSmallestFlowDecay($world->getBlockAt($x, $y, $z - 1), $smallestFlowDecay);
            $smallestFlowDecay = $this->getSmallestFlowDecay($world->getBlockAt($x, $y, $z + 1), $smallestFlowDecay);
            $smallestFlowDecay = $this->getSmallestFlowDecay($world->getBlockAt($x - 1, $y, $z), $smallestFlowDecay);
            $smallestFlowDecay = $this->getSmallestFlowDecay($world->getBlockAt($x + 1, $y, $z), $smallestFlowDecay);
 
            $newDecay = $smallestFlowDecay + $multiplier;
            $falling = false;
 
            if($newDecay > self::MAX_DECAY || $smallestFlowDecay < 0){
                $newDecay = -1;
            }
 
            if($this->getEffectiveFlowDecay($world->getBlockAt($x, $y + 1, $z)) >= 0){
                $falling = true;
            }
 
            $minAdjacentSources = $this->getMinAdjacentSourcesToFormSource();
            if($minAdjacentSources !== null && $this->adjacentSources >= $minAdjacentSources){
                $bottomBlock = $world->getBlockAt($x, $y - 1, $z);
                if($bottomBlock->isSolid() || ($bottomBlock instanceof Liquid && $bottomBlock->hasSameTypeId($this) && $bottomBlock->isSource())){
                    $newDecay = 0;
                    $falling = false;
                }
            }
 
            if($falling !== $this->falling || (!$falling && $newDecay !== $this->decay)){
                if(!$falling && $newDecay < 0){
                    $world->setBlockAt($x, $y, $z, VanillaBlocks::AIR());
                    return;
                }
 
                $this->falling = $falling;
                $this->decay = $falling ? 0 : $newDecay;
                $world->setBlockAt($x, $y, $z, $this); //local block update will cause an update to be scheduled
            }
        }
 
        $bottomBlock = $world->getBlockAt($x, $y - 1, $z);
 
        $this->flowIntoBlock($bottomBlock, 0, true);
 
        if($this->isSource() || !$bottomBlock->canBeFlowedInto()){
            if($this->falling){
                $adjacentDecay = 1; //falling liquid behaves like source block
            }else{
                $adjacentDecay = $this->decay + $multiplier;
            }
 
            if($adjacentDecay <= self::MAX_DECAY){
                $calculator = new MinimumCostFlowCalculator($world, $this->getFlowDecayPerBlock(), $this->canFlowInto(...));
                foreach($calculator->getOptimalFlowDirections($x, $y, $z) as $facing){
                    [$dx, $dy, $dz] = Facing::OFFSET[$facing];
                    $this->flowIntoBlock($world->getBlockAt($x + $dx, $y + $dy, $z + $dz), $adjacentDecay, false);
                }
            }
        }
 
        $this->checkForHarden();
    }
 
    protected function flowIntoBlock(Block $block, int $newFlowDecay, bool $falling) : void{
        if($this->canFlowInto($block) && !($block instanceof Liquid)){
            $new = clone $this;
            $new->falling = $falling;
            $new->decay = $falling ? 0 : $newFlowDecay;
 
            $ev = new BlockSpreadEvent($block, $this, $new);
            $ev->call();
            if(!$ev->isCancelled()){
                $world = $this->position->getWorld();
                if($block->getTypeId() !== BlockTypeIds::AIR){
                    $world->useBreakOn($block->position);
                }
 
                $world->setBlock($block->position, $ev->getNewState());
            }
        }
    }
 
    private function getSmallestFlowDecay(Block $block, int $decay) : int{
        if(!($block instanceof Liquid) || !$block->hasSameTypeId($this)){
            return $decay;
        }
 
        $blockDecay = $block->decay;
 
        if($block->isSource()){
            ++$this->adjacentSources;
        }elseif($block->falling){
            $blockDecay = 0;
        }
 
        return ($decay >= 0 && $blockDecay >= $decay) ? $decay : $blockDecay;
    }
 
    protected function checkForHarden() : bool{
        return false;
    }
 
    protected function liquidCollide(Block $cause, Block $result) : bool{
        if(BlockEventHelper::form($this, $result, $cause)){
            $this->position->getWorld()->addSound($this->position->add(0.5, 0.5, 0.5), new FizzSound(2.6 + (lcg_value() - lcg_value()) * 0.8));
        }
        return true;
    }
 
    protected function canFlowInto(Block $block) : bool{
        return
            $this->position->getWorld()->isInWorld($block->position->x, $block->position->y, $block->position->z) &&
            $block->canBeFlowedInto() &&
            !($block instanceof Liquid && $block->isSource()); //TODO: I think this should only be liquids of the same type
    }
}