(svn r1696) Use GetTileSlope() instead of FindLandscapeHeightByTile() where it is sufficient. FindLandscapeHeightByTile() uses GetTileSlope() internally and adds some more info, which is discarded in these cases.

While touching the code make a bit more clear how GetBridgeHeight() works. 

3 files changed, 10 insertions, 19 deletions

diff --git a/train_cmd.c b/train_cmd.c
index 5853116b1..1ce1631ee 100644
--- a/train_cmd.c
+++ b/train_cmd.c
@@ -2049,13 +2049,13 @@ static bool CheckCompatibleRail(const Vehicle *v, TileIndex tile)
 
 		case MP_TUNNELBRIDGE:
 			if ((_map5[tile] & 0xC0) == 0xC0) { // is bridge middle part?
-				TileInfo ti;
-				FindLandscapeHeightByTile(&ti, tile);
+				uint height;
+				uint tileh = GetTileSlope(tile, &height);
 
 				// correct Z position of a train going under a bridge on slopes
-				if (CORRECT_Z(ti.tileh)) ti.z += 8;
+				if (CORRECT_Z(tileh)) height += 8;
 
-				if (v->z_pos != ti.z) return true; // train is going over bridge
+				if (v->z_pos != height) return true; // train is going over bridge
 			}
 			break;
 
diff --git a/tunnelbridge_cmd.c b/tunnelbridge_cmd.c
index 156ea8a23..62418e2d3 100644
--- a/tunnelbridge_cmd.c
+++ b/tunnelbridge_cmd.c
@@ -905,9 +905,7 @@ int32 DoConvertTunnelBridgeRail(uint tile, uint totype, bool exec)
 static uint GetBridgeHeight(const TileInfo *ti)
 {
 	uint delta;
-	TileInfo ti_end;
-	uint tile = ti->tile;
-	uint z_correction = 0;
+	TileIndex tile = ti->tile;
 
 	// find the end tile of the bridge.
 	delta = (_map5[tile] & 1) ? TILE_XY(0,1) : TILE_XY(1,0);
@@ -916,14 +914,10 @@ static uint GetBridgeHeight(const TileInfo *ti)
 		tile += delta;
 	} while (_map5[tile] & 0x40);	// while bridge middle parts
 
-	// if the end of the bridge is on a tileh 7, the z coordinate is 1 tile too low
-	// correct it.
-	FindLandscapeHeightByTile(&ti_end, tile);
-	if (HASBIT(1 << 7, ti_end.tileh))
-		z_correction += 8;
-
-	// return the height there (the height of the NORTH CORNER)
-	return TilePixelHeight(tile) + z_correction;
+	/* Return the height there (the height of the NORTH CORNER)
+	 * If the end of the bridge is on a tileh 7 (all raised, except north corner),
+	 * the z coordinate is 1 height level too low. Compensate for that */
+	return TilePixelHeight(tile) + (GetTileSlope(tile, NULL) == 7 ? 8 : 0);
 }
 
 static const byte _bridge_foundations[2][16] = {
diff --git a/vehicle.c b/vehicle.c
index ffe2e392e..915da38da 100644
--- a/vehicle.c
+++ b/vehicle.c
@@ -82,10 +82,7 @@ static inline uint Correct_Z(uint tileh)
 
 uint GetCorrectTileHeight(TileIndex tile)
 {
-	TileInfo ti;
-
-	FindLandscapeHeightByTile(&ti, tile);
-	return Correct_Z(ti.tileh);
+	return Correct_Z(GetTileSlope(tile, NULL));
 }
 
 bool EnsureNoVehicleZ(TileIndex tile, byte z)