From 6e9b9526234627afb33d0bfd937b448426d8ec16 Mon Sep 17 00:00:00 2001
From: smatz <smatz@openttd.org>
Date: Tue, 19 Feb 2008 17:45:30 +0000
Subject: [PATCH] (svn r12186) -Fix [FS#1784](r12169): assert when trying to
 play tile sound at NW border of map (placing buyos, leveling land)

---
 src/sound.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/sound.cpp b/src/sound.cpp
index 960794bbd7..9fed4a689a 100644
--- a/src/sound.cpp
+++ b/src/sound.cpp
@@ -241,7 +241,8 @@ void SndPlayTileFx(SoundFx sound, TileIndex tile)
 	/* emits sound from center of the tile */
 	int x = TileX(tile) * TILE_SIZE + TILE_SIZE / 2;
 	int y = TileY(tile) * TILE_SIZE - TILE_SIZE / 2;
-	Point pt = RemapCoords(x, y, GetSlopeZ(x, y));
+	uint z = (y < 0 ? 0 : GetSlopeZ(x, y));
+	Point pt = RemapCoords(x, y, z);
 	y += 2 * TILE_SIZE;
 	Point pt2 = RemapCoords(x, y, GetSlopeZ(x, y));
 	SndPlayScreenCoordFx(sound, pt.x, pt2.x, pt.y, pt2.y);