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Dynamic Paint Substeps don't work
Needs Triage, NormalPublic

Description

System Information
Operating system: MacOS Big Sur 11.2.2
Graphics card: Intel Iris Plus Graphics 1536 MB

Blender Version
Broken: 2.92.0 (release)
Worked: ?

When I use substeps for Dynamic Paint it doesn't make a difference in the images generated.

Exact steps for others to reproduce the error
Add particle system to default cube
Turn the cube into a Dynamic Paint Brush, set Source to Particle System, Particle System to "ParticleSettings"
Add in a plane and scale it by 4
Turn the plane into a Dynamic Paint Canvas, set Format it to image
Set Sub-Steps to 20 (maximum)
(Optional: Set Plane cache path to something reasonable you would find later)
Click "Bake Image Sequence"
(Optional: Set Sub-Steps to 0 (minimum)
(Optional: Set Plane cache path to something different than before)
(Optional: Click "Bake Image Sequence")
(Optional: Compare baked images)

If you compare 0 Sub-Steps to 20 Sub-Steps they look the same; I think Sub-Steps has no influence on the result whatsoever.

Based on the default startup or an attached .blend file (as simple as possible).

Event Timeline

Philipp Oeser (lichtwerk) changed the task status from Needs Triage to Needs Information from Developers.Thu, Apr 8, 9:29 AM

In code, it looks like only the brush objects (so Source being anything but Particle System) are updated specifically for each subframe.
Afaict, their particle data is not available in subframes for dynamic paint to use though.

It would be nice to somehow have that data available [maybe in conjunction with specifying a higher value for Physics > Integration > Subframes on the particle system], but this would be more like a feature request (which is not handled in this bugtracker).

I am not 100% sure though if this is by design, so will have the module devs have a confirming look...

It was working in 2.97 so i don't consider it a feature request; maybe it's a degradation?

Philipp Oeser (lichtwerk) changed the task status from Needs Information from Developers to Needs Triage.Thu, Apr 8, 9:58 AM

It was working in 2.97 so i don't consider it a feature request; maybe it's a degradation?

Thx getting back, will double-check then.