Game_window *gwin, Game_object *obj, int xtiles, int ytiles, Tile_coord c
Tile_coord t, Tile_coord c
inline Tile_coord Rotate90r	(	Game_window *gwin,	Game_object *obj,	int xtiles, int ytiles,		// Object dimensions.	Tile_coord c			// Rotate around this.	)	{					// Rotate hot spot.	Tile_coord r = Rotate90r(obj->get_abs_tile_coord(), c);					// New hotspot is what used to be the					//   upper-right corner.	r.tx = (r.tx + ytiles + c_num_tiles)%c_num_tiles;	r.ty = (r.ty + c_num_tiles)%c_num_tiles;	return r;	}