From 1c3d89cfefeae9123f28ddd1afa4210d72cc7cdd Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <odigiman@gmail.com>
Date: Wed, 29 Mar 2017 11:34:43 +0100
Subject: [PATCH] Fixed lighting issues with subchunks containing no blocks A
 subchunk with no blocks is not necessarily empty.

---
 src/pocketmine/level/format/Chunk.php    | 4 ++--
 src/pocketmine/level/format/SubChunk.php | 7 +++++--
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/pocketmine/level/format/Chunk.php b/src/pocketmine/level/format/Chunk.php
index 52684896c..9f47296cf 100644
--- a/src/pocketmine/level/format/Chunk.php
+++ b/src/pocketmine/level/format/Chunk.php
@@ -307,7 +307,7 @@ class Chunk{
 	 * @param int $level 0-15
 	 */
 	public function setBlockSkyLight(int $x, int $y, int $z, int $level){
-		if($this->getSubChunk($y >> 4)->setBlockSkyLight($x, $y & 0x0f, $z, $level)){
+		if($this->getSubChunk($y >> 4, true)->setBlockSkyLight($x, $y & 0x0f, $z, $level)){
 			$this->hasChanged = true;
 		}
 	}
@@ -334,7 +334,7 @@ class Chunk{
 	 * @param int $level 0-15
 	 */
 	public function setBlockLight(int $x, int $y, int $z, int $level){
-		if($this->getSubChunk($y >> 4)->setBlockLight($x, $y & 0x0f, $z, $level)){
+		if($this->getSubChunk($y >> 4, true)->setBlockLight($x, $y & 0x0f, $z, $level)){
 			$this->hasChanged = true;
 		}
 	}
diff --git a/src/pocketmine/level/format/SubChunk.php b/src/pocketmine/level/format/SubChunk.php
index 38cb57194..8a5cc5be6 100644
--- a/src/pocketmine/level/format/SubChunk.php
+++ b/src/pocketmine/level/format/SubChunk.php
@@ -47,8 +47,11 @@ class SubChunk{
 	}
 
 	public function isEmpty() : bool{
-		assert(strlen($this->ids) === 4096, "Wrong length of ID array, expecting 4096 bytes, got " . strlen($this->ids));
-		return substr_count($this->ids, "\x00") === 4096;
+		return (
+			substr_count($this->ids, "\x00") === 4096 and
+			substr_count($this->skyLight, "\xff") === 2048 and
+			substr_count($this->blockLight, "\x00") === 2048
+		);
 	}
 
 	public function getBlockId(int $x, int $y, int $z) : int{