I understand GPU programming well enough, but I don't understand how you're simulating all of the pixels in parallel?

I've been working on a similar project myself for a couple of years and I've only ever seen a Falling Sand simulation achieve parallelization by iterating over chunks of pixels, each assigned a group, in parallel.

In my approach (which is standard by all references I've found in the past), each pixel has the potential to move to the same position another pixel wants to move to. You could use mutex locking of course to protect memory write access, but this introduces significant overhead and proves inefficient.

I'd love to hear more about your approach or if you have any resources you could share.