Pop Grains — Sprinkles

Using a similar technique, but adding an attribute transfer to transfer the colors from the moving cubes to the particles. This required some attribute transfer wrangling.

Normally you use attribute transfer with no issues, and if you want the attributes to stay, you apply a sop solver to allow access to the previous position. I found that the attribute transfer was overriding my point position. Despite listing only Cd and ^P the points were being moved to the previous frame, toggling the checkboxes as well.

I have used attribute transfer for many purposes but this particular case was unusual. The usual attribute transfer was inside a SOP solver to keep the value from each previous step. I mistakenly tried putting an attribute transfer outside the level to maintain the correct point position. After seeing popping of the colors during rendering, I realized that was not the best method — google led to videos that also did not help (as was mentioned in several forums). The solution was to simply put a point wrangle inside the sop solver after the attribute transfer. Problem solved. Seen below.

This one was simmed in 5.5 hours on my personal desktop (Intel Core i9-10900CPU 2.8GHz, 128 GB RAM, NVIDIA GeForce RTX 2060) — that's the one I went with after several attempts to get out all the possible jitter/pops. Substeps can be costly, and behavior can change; this was the best of several — with a particle count of about 2 million (2,019,584).

Definitely culling geometry paid off for this one as did caching the SOP solver (about 52 GB total — be sure to delete attributes not needed in your sim above; this was 92 GB on a previous iteration just from attributes) for the color transfer after having cached the particles (63 GB). On a test of the last frame at 320×320 res it took 7 minutes; after caching the SOP solver, render time went down to 1 minute. For full resolution the render time was 4 minutes per frame.