From 716c1f29b4dd65cdb60348bad932d11de3267a5e Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <odigiman@gmail.com>
Date: Tue, 24 Oct 2017 10:23:07 +0100
Subject: [PATCH] Fixed slabs again

---
 src/pocketmine/block/Block.php |  2 +-
 src/pocketmine/block/Slab.php  | 24 ++++++++++++++----------
 src/pocketmine/level/Level.php |  4 ++--
 3 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/src/pocketmine/block/Block.php b/src/pocketmine/block/Block.php
index 64eda69b8..ff99e072f 100644
--- a/src/pocketmine/block/Block.php
+++ b/src/pocketmine/block/Block.php
@@ -164,7 +164,7 @@ class Block extends Position implements BlockIds, Metadatable{
 		return false;
 	}
 
-	public function canBePlacedAt(Block $blockReplace, Vector3 $clickVector) : bool{
+	public function canBePlacedAt(Block $blockReplace, Vector3 $clickVector, int $face, bool $isClickedBlock) : bool{
 		return $blockReplace->canBeReplaced();
 	}
 
diff --git a/src/pocketmine/block/Slab.php b/src/pocketmine/block/Slab.php
index 8af41753a..08d97ab19 100644
--- a/src/pocketmine/block/Slab.php
+++ b/src/pocketmine/block/Slab.php
@@ -36,16 +36,20 @@ abstract class Slab extends Transparent{
 
 	abstract public function getDoubleSlabId() : int;
 
-	public function canBePlacedAt(Block $blockReplace, Vector3 $clickVector) : bool{
-		return parent::canBePlacedAt($blockReplace, $clickVector) or
-			(
-				$blockReplace->getId() === $this->getId() and
-				$blockReplace->getVariant() === $this->getVariant() and
-				(
-					(($blockReplace->getDamage() & 0x08) !== 0 and ($clickVector->y <= 0.5 or $clickVector->y === 1.0)) or //top slab, fill bottom half
-					(($blockReplace->getDamage() & 0x08) === 0 and ($clickVector->y >= 0.5 or $clickVector->y === 0.0)) //bottom slab, fill top half
-				)
-			);
+	public function canBePlacedAt(Block $blockReplace, Vector3 $clickVector, int $face, bool $isClickedBlock) : bool{
+		if(parent::canBePlacedAt($blockReplace, $clickVector, $face, $isClickedBlock)){
+			return true;
+		}
+
+		if($blockReplace->getId() === $this->getId() and $blockReplace->getVariant() === $this->getVariant()){
+			if(($blockReplace->getDamage() & 0x08) !== 0){ //Trying to combine with top slab
+				return $clickVector->y <= 0.5 or (!$isClickedBlock and $face === Vector3::SIDE_UP);
+			}else{
+				return $clickVector->y >= 0.5 or (!$isClickedBlock and $face === Vector3::SIDE_DOWN);
+			}
+		}
+
+		return false;
 	}
 
 	public function place(Item $item, Block $blockReplace, Block $blockClicked, int $face, Vector3 $facePos, Player $player = null) : bool{
diff --git a/src/pocketmine/level/Level.php b/src/pocketmine/level/Level.php
index 3321d7a8d..36cdac716 100644
--- a/src/pocketmine/level/Level.php
+++ b/src/pocketmine/level/Level.php
@@ -1793,10 +1793,10 @@ class Level implements ChunkManager, Metadatable{
 			return false;
 		}
 
-		if($hand->canBePlacedAt($blockClicked, $facePos)){
+		if($hand->canBePlacedAt($blockClicked, $facePos, $face, true)){
 			$blockReplace = $blockClicked;
 			$hand->position($blockReplace);
-		}elseif(!$hand->canBePlacedAt($blockReplace, $facePos)){
+		}elseif(!$hand->canBePlacedAt($blockReplace, $facePos, $face, false)){
 			return false;
 		}