oGridForLineOfSight

var width = room_width div CellWidth;
var height = room_height div CellHeight
global.grid = ds_grid_create(width, height);

var lay_id_ground = layer_get_id("GroundTiles");
var map_id_ground = layer_tilemap_get_id(lay_id_ground);
var lay_id_shadows = layer_get_id("ShadowTiles");
var map_id_shadows = layer_tilemap_get_id(lay_id_shadows);

for (var yy = 0; yy < height; ++yy) {
    for (var xx = 0; xx < width; ++xx) {
		ds_grid_set(global.grid, xx, yy, 1);
		tilemap_set(map_id_ground, 1, xx, yy);
		tilemap_set(map_id_shadows, 1, xx, yy);
	}
}