--- a/src/newgrf_commons.cpp	Mon Jun 04 20:46:01 2007 +0000
+++ b/src/newgrf_commons.cpp	Tue Jun 05 01:49:08 2007 +0000
@@ -6,6 +6,8 @@
 
 #include "stdafx.h"
 #include "openttd.h"
+#include "variables.h"
+#include "clear_map.h"
 #include "town.h"
 #include "industry.h"
 #include "newgrf.h"
@@ -148,3 +150,18 @@
 		entity_overrides[i] = invalid_ID;
 	}
 }
+
+/** Function used by houses (and soon industries) to get information
+ * on type of "terrain" the tile it is queries sits on.
+ * @param tile TileIndex of the tile been queried
+ * @return value corresponding to the grf expected format:
+ *         Terrain type: 0 normal, 1 desert, 2 rainforest, 4 on or above snowline */
+uint32 GetTerrainType(TileIndex tile)
+{
+	switch (_opt.landscape) {
+		case LT_TROPIC: return GetTropicZone(tile) == TROPICZONE_DESERT ? 1 : 2;
+		case LT_ARCTIC: return (GetClearGround(tile) == CLEAR_SNOW) ? 4 : 0;
+		default:        return 0;
+	}
+}
+

--- a/src/newgrf_commons.h	Mon Jun 04 20:46:01 2007 +0000
+++ b/src/newgrf_commons.h	Tue Jun 05 01:49:08 2007 +0000
@@ -66,4 +66,6 @@
 
 extern HouseOverrideManager _house_mngr;
 
+uint32 GetTerrainType(TileIndex tile);
+
 #endif /* NEWGRF_COMMONS_H */

--- a/src/newgrf_house.cpp	Mon Jun 04 20:46:01 2007 +0000
+++ b/src/newgrf_house.cpp	Tue Jun 05 01:49:08 2007 +0000
@@ -169,15 +169,6 @@
 	return map_class_count << 24 | town_class_count << 16 | map_id_count << 8 | town_id_count;
 }
 
-static uint32 GetTerrainType(TileIndex tile)
-{
-	switch (_opt.landscape) {
-		case LT_TROPIC: return GetTropicZone(tile) == TROPICZONE_DESERT ? 1 : 2;
-		case LT_ARCTIC: return GetTileZ(tile) >= GetSnowLine() ? 4 : 0;
-		default:        return 0;
-	}
-}
-
 static uint32 GetGRFParameter(HouseID house_id, byte parameter)
 {
 	const HouseSpec *hs = GetHouseSpecs(house_id);