From a3b73d95a755ea9615b9eae5f47aba2311c1af96 Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <odigiman@gmail.com>
Date: Wed, 23 Oct 2019 21:01:19 +0100
Subject: [PATCH] LightUpdate: allow providing effective light levels for
 propagation, fix #2999

---
 src/world/light/LightUpdate.php    | 18 ++++++++++++------
 src/world/light/SkyLightUpdate.php |  9 +++++++++
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/src/world/light/LightUpdate.php b/src/world/light/LightUpdate.php
index b608f475a0..c91a68ac47 100644
--- a/src/world/light/LightUpdate.php
+++ b/src/world/light/LightUpdate.php
@@ -67,6 +67,13 @@ abstract class LightUpdate{
 
 	abstract public function recalculateNode(int $x, int $y, int $z) : void;
 
+	protected function getEffectiveLight(int $x, int $y, int $z) : int{
+		if($this->subChunkHandler->moveTo($x, $y, $z, false)){
+			return $this->currentLightArray->get($x & 0xf, $y & 0xf, $z & 0xf);
+		}
+		return 0;
+	}
+
 	protected function getHighestAdjacentLight(int $x, int $y, int $z) : int{
 		$adjacent = 0;
 		foreach([
@@ -77,7 +84,7 @@ abstract class LightUpdate{
 			[$x, $y, $z + 1],
 			[$x, $y, $z - 1]
 		] as [$x1, $y1, $z1]){
-			if($this->subChunkHandler->moveTo($x1, $y1, $z1, false) and ($adjacent = max($adjacent, $this->currentLightArray->get($x1 & 0xf, $y1 & 0xf, $z1 & 0xf))) === 15){
+			if(($adjacent = max($adjacent, $this->getEffectiveLight($x1, $y1, $z1))) === 15){
 				break;
 			}
 		}
@@ -125,6 +132,9 @@ abstract class LightUpdate{
 			foreach($points as list($cx, $cy, $cz)){
 				if($this->subChunkHandler->moveTo($cx, $cy, $cz, true)){
 					$this->computeRemoveLight($cx, $cy, $cz, $oldAdjacentLight);
+				}elseif($this->getEffectiveLight($cx, $cy, $cz) > 0 and !isset($this->spreadVisited[$index = World::blockHash($cx, $cy, $cz)])){
+					$this->spreadVisited[$index] = true;
+					$this->spreadQueue->enqueue([$cx, $cy, $cz]);
 				}
 			}
 		}
@@ -134,11 +144,7 @@ abstract class LightUpdate{
 
 			unset($this->spreadVisited[World::blockHash($x, $y, $z)]);
 
-			if(!$this->subChunkHandler->moveTo($x, $y, $z, false)){
-				continue;
-			}
-
-			$newAdjacentLight = $this->currentLightArray->get($x & 0xf, $y & 0xf, $z & 0xf);
+			$newAdjacentLight = $this->getEffectiveLight($x, $y, $z);
 			if($newAdjacentLight <= 0){
 				continue;
 			}
diff --git a/src/world/light/SkyLightUpdate.php b/src/world/light/SkyLightUpdate.php
index 59ab9e98c4..f06b2b3c88 100644
--- a/src/world/light/SkyLightUpdate.php
+++ b/src/world/light/SkyLightUpdate.php
@@ -24,6 +24,7 @@ declare(strict_types=1);
 namespace pocketmine\world\light;
 
 use pocketmine\block\BlockFactory;
+use pocketmine\world\World;
 use function max;
 
 class SkyLightUpdate extends LightUpdate{
@@ -31,6 +32,14 @@ class SkyLightUpdate extends LightUpdate{
 		$this->currentLightArray = $this->subChunkHandler->currentSubChunk->getBlockSkyLightArray();
 	}
 
+	protected function getEffectiveLight(int $x, int $y, int $z) : int{
+		if($y >= World::Y_MAX){
+			$this->subChunkHandler->invalidate();
+			return 15;
+		}
+		return parent::getEffectiveLight($x, $y, $z);
+	}
+
 	public function recalculateNode(int $x, int $y, int $z) : void{
 		$chunk = $this->world->getChunk($x >> 4, $z >> 4);
 		if($chunk === null){