i = gridl + 30;
while (i < gridr)
{
    j = gridu + 10;
    while (j < gridd)
    {
        if (collision_point(i, j, obj_blackbox_o, 0, 1))
        {
            with (collision_point(i, j, obj_blackbox_o, 0, 1))
                event_user(1);
        }
        j += 20;
    }
    i += 20;
}