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Mantaflow grid visible in spray, foam and bubbles particles
Confirmed, NormalPublicBUG

Description

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1060/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 451.67

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-08-21 15:43, hash: rB74ded456b3fa

Short description of error
Spray, foam and bubbles particles take the shape of the grid when simulated.

Exact steps for others to reproduce the error

  • Open the file
  • Bake
  • Display spray, foam or bubbles particles

Foam and bubble particles are very blocky and unnatural

Event Timeline

Richard Antalik (ISS) changed the task status from Needs Triage to Needs Information from User.Aug 25 2020, 6:09 AM

Please upload simplest possible .blend file that represents the issue. I don't think you need 3GB of data for that. Even if those are caches, we need to re-bake(should be quick as well) to confirm issue.

Sorry for that, here is the file without the caches, and the videos :

Bubbles:

Foam:

Spray:

Raimund Klink (Raimund58) changed the task status from Needs Information from User to Needs Triage.Aug 26 2020, 3:57 PM

Could reproduce it in Blender 2.91 (commit date: 2020-08-25 19:28, hash: 396d39c6b904)

Richard Antalik (ISS) changed the task status from Needs Triage to Confirmed.Aug 27 2020, 11:46 AM

Looking into this right now. There was a similar issue in T73552 - seems like foam and bubbles still have issues.

Jacques Lucke (JacquesLucke) changed the subtype of this task from "Report" to "Bug".Nov 3 2020, 1:46 PM

Hey, I just wanted to know if there was any news about this bug ?

@Sebastián Barschkis (sebbas) Is this indeed similar to T73552? I am a bit curios about the outcome :)

@Raimund Klink (Raimund58) The reason for the grid patterns are the hard cut-off values for spray, foam, bubble transitions. I.e. the values that determine when a particle changes type.

For now, the only way I see to get around this is to use a higher particle grid resolution (e.g. particle upres = 2 -> twice the base resolution). Depending on the scene and hardware limits, I would also lower the sampling values to better control the number of particles.

Alright, thank you for the info :)