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Dynamic Paint Works Only in Viewport Render
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I created a material effect that requires the use of Blender's Dynamic Paint to work the best way possible. It works correctly with a baked image sequence, but vertex colors don't work. There is another effect that does work in the rendered scene with vertex colors, on both the wetmap and paint map, but this file doesn't seem to work.

System Information
Windows 10 Home

Nvidia GeForce GTX 970

Blender Version
Broken: e8299c8

Short description of error

Full rendered materials do not respond to dynamic paint vertex color influence.

Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps

To repeat:

  1. Download the .blend file,
  1. go to any frame between frames 150 and 191,
  1. check in viewport render
  1. perform full render.

Interestingly, it works on both the paintmap and wetmap on an entirely new scene, but not this one with this specific material.



Event Timeline

Aaron Carlisle (Blendify) triaged this task as Confirmed, Medium priority.

The problem comes from the subsurf modifier (it is disabled in preview mode (0), while enabled for final rendering).

Note that if you put dynamic paint modifier before subsurf in the stack, everything works OK.

Mehh, this even more complicated… There is a dependency cycle here, detected by legacy depsgraph. So tried with new depsgraph and… got a nice crash on startup (first evaluation of the scene) - new one also reports a dependency cycle btw.

Summoning @Sergey Sharybin (sergey) here, maybe he can figure out what’s happening here more easily than me :/

Bah, am now getting a straight crash when trying to switch to Cycles viewport render…

blender: /home/i74700deb64/blender/__work__/src/intern/cycles/blender/blender_mesh.cpp:67: void ccl::face_split_tri_indices(int, int*, int*): Assertion `face_flag & FACE_FLAG_DIVIDE_13' failed.

@Sergey Sharybin (sergey) assigning to you since I suspect some nasty DEG issue is at play here (and maybe a new Cycles one too? did not crash back in April.

Ok, so now crash seems to have disappeared again. Issue with rendering remains though. :)

This comment was removed by H S (joemoehobo).
hsab (hsab) added a subscriber: hsab (hsab).EditedDec 31 2018, 3:45 AM

Any updates on this? There seems to be issues with rendering vertex colors that are manipulated using python api, or addons when modifiers are present. Viewport is fine but rendered images do not reflect the changes.

Blender 2.80 (sub 39), Commit date: 2018-12-29 18:10, Hash 266b1e2cdbc1
x86_64 Linux 4.14.90-1-MANJARO

More info:

It works in LookDev mode.

@Clément Foucault (fclem), not sure if that's by design or some issue is involved?

Clément Foucault (fclem) closed this task as Archived.Jul 10 2019, 3:20 PM

The issue here is that dynamic paint does not work if after an enabled subsurf modifier. Putting it before and everything is working.

This kind of make sense since the dynamic paint modifier modify the original mesh data.

So closing as working as expected. But feel free to reopen with more detail if I got it wrong.