Thanks!! I've been looking for an algo to draw pixel positions in a pseudorandom way only once. I didn't know a way to do it without storing and shuffling all positions. Now, I only need to draw a centered filled circle, so there might be a prime number for it, and even if the prime only does it for a given amount of points, I could switch to other primes until the circle is filled, and get an optimal and compressed single-visit scattering algo.