From 7fdfb8644169a25805afd32f00ced38c1c14cec8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20Havl=C3=AD=C4=8Dek?=
 <80639037+havel06@users.noreply.github.com>
Date: Wed, 25 Jan 2023 21:46:34 +0100
Subject: Allow certain blocks to be placed on top of upside-down stairs/slabs
 (#5468)

* Placing certain blocks on top of upside down slabs and stairs

* remove TODO

* fix style errors

* IsAnyStairType helper function

* Block placement on stairs and slabs
---
 src/Blocks/BlockButton.h | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

(limited to 'src/Blocks/BlockButton.h')

diff --git a/src/Blocks/BlockButton.h b/src/Blocks/BlockButton.h
index d703d73bd..1a141eff3 100644
--- a/src/Blocks/BlockButton.h
+++ b/src/Blocks/BlockButton.h
@@ -1,10 +1,15 @@
 #pragma once
 
 #include "BlockHandler.h"
+#include "BlockSlab.h"
+#include "BlockStairs.h"
 #include "../BlockInfo.h"
 #include "../Chunk.h"
+#include "Defines.h"
+#include "Entities/Player.h"
 #include "Mixins.h"
 #include "ChunkInterface.h"
+#include "World.h"
 
 
 
@@ -132,7 +137,37 @@ private:
 			return false;
 		}
 		BLOCKTYPE SupportBlockType;
-		a_Chunk.UnboundedRelGetBlockType(SupportRelPos, SupportBlockType);
+		NIBBLETYPE SupportBlockMeta;
+		a_Chunk.UnboundedRelGetBlock(SupportRelPos, SupportBlockType, SupportBlockMeta);
+		eBlockFace Face = BlockMetaDataToBlockFace(a_Meta);
+
+		// upside down slabs
+		if (cBlockSlabHandler::IsAnySlabType(SupportBlockType))
+		{
+			return (Face == BLOCK_FACE_YP) && (SupportBlockMeta & E_META_WOODEN_SLAB_UPSIDE_DOWN);
+		}
+
+		// stairs (top and sides)
+		if (cBlockStairsHandler::IsAnyStairType(SupportBlockType))
+		{
+			switch (Face)
+			{
+				case eBlockFace::BLOCK_FACE_YP:
+					return (SupportBlockMeta & E_BLOCK_STAIRS_UPSIDE_DOWN);
+				case eBlockFace::BLOCK_FACE_XP:
+					return ((SupportBlockMeta & 0b11) == E_BLOCK_STAIRS_XP);
+				case eBlockFace::BLOCK_FACE_XM:
+					return ((SupportBlockMeta & 0b11) == E_BLOCK_STAIRS_XM);
+				case eBlockFace::BLOCK_FACE_ZP:
+					return ((SupportBlockMeta & 0b11) == E_BLOCK_STAIRS_ZP);
+				case eBlockFace::BLOCK_FACE_ZM:
+					return ((SupportBlockMeta & 0b11) == E_BLOCK_STAIRS_ZM);
+				default:
+				{
+					return false;
+				}
+			}
+		}
 
 		return cBlockInfo::FullyOccupiesVoxel(SupportBlockType);
 	}
-- 
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