var i, j, k;
for (i=0; i<array_length(global.map); i++) {
	for (j=0; j<array_length(global.map[i]); j++) {
		draw_set_color(c_white);
		draw_rectangle(
			i*global.tilesize.x,
			j*global.tilesize.y,
			(i+1)*global.tilesize.x,
			(j+1)*global.tilesize.y, false
		);
		for (k=0; k<array_length(global.map[i][j].overlays); k++) {
			draw_set_color(global.map[i][j].overlays[k]);
			draw_set_alpha(.4);
			draw_rectangle(
				i*global.tilesize.x,
				j*global.tilesize.y,
				(i+1)*global.tilesize.x,
				(j+1)*global.tilesize.y, false
			);
			draw_set_alpha(1);
		}
	}
}
draw_set_color(c_black);
var i, j;
for (i=0; i<array_length(global.map); i++) {
	for (j=0; j<array_length(global.map[i]); j++) {
		draw_rectangle(
			i*global.tilesize.x,
			j*global.tilesize.y,
			(i+1)*global.tilesize.x-1,
			(j+1)*global.tilesize.y-1, true
		);
	}
}