var i, j, l, m, n, chunk, tile, bg, xx, yy, left, top;
game = objGame;

mode = -1;

bottomLayer[ 0] = 10000;
bottomLayer[ 1] = 9500;
bottomLayer[ 2] = 9000;
bottomLayers = 3;

topLayer[ 0] = -10000;
topLayers = 1;

while( mode < 2) {
    for( i = 0;i < room_width;i += 16) {
        for( j = 0;j < room_height;j += 16) {
            if (( i mod 256) == 0) && (( j mod 256) == 0) {
                surface_set_target( game.surface);
                chunk = instance_create( i, j, objChunk);
                chunk.depth = mode * 500;
                surface_set_target( chunk.surface);
                draw_clear_alpha( 0, 0);
            }
            switch( mode) {
                case -1:
                    for( l = 0;l < bottomLayers;l += 1) {
                        tile = tile_layer_find( bottomLayer[ l], i, j);
                        if tile_exists( tile) {
                            bg = tile_get_background( tile);
                            xx = i mod 256;
                            yy = j mod 256;
                            left = tile_get_left( tile);
                            top = tile_get_top( tile);
                            draw_background_part( bg, left, top, 16, 16, xx, yy);
                        }
                    }
                break;
                case 1:
                    for( l = 0;l < topLayers;l += 1) {
                        tile = tile_layer_find( topLayer[ l], i, j);
                        if tile_exists( tile) {
                            bg = tile_get_background( tile);
                            xx = i mod 256;
                            yy = j mod 256;
                            left = tile_get_left( tile);
                            top = tile_get_top( tile);
                            draw_background_part( bg, left, top, 16, 16, xx, yy);
                        }
                    }
                break;
            }
        }
    }
    mode += 2;
}
surface_set_target( game.surface);
for( m = 0;m < bottomLayers;m += 1) {
    tile_layer_hide( bottomLayer[ m]);
}
for( n = 0;n < topLayers;n += 1) {
    tile_layer_hide( topLayer[ n]);
}