Maniphest T101792

New hair curves do not render properly first time in EEVEE with motion blur enabled
Closed, Resolved
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Assigned To
Clément Foucault (fclem)
Authored By
Sun Kim (persun)
Oct 13 2022, 11:33 AM
Tags
  • BF Blender
  • EEVEE & Viewport
  • Nodes & Physics
Subscribers
Omar Emara (OmarSquircleArt)
Simon Thommes (simonthommes)
Sun Kim (persun)

Description

System Information
Operating system: Windows-10-10.0.19043-SP0 64 Bits
Graphics card: Radeon RX 570 Series ATI Technologies Inc. 4.5.0 Core Profile Context 22.10.1.221003

Blender Version
Broken: version: 3.4.0 Alpha, branch: master, commit date: 2022-10-10 08:50, hash: rBf77eadc20367
Worked: n/a (probably since the new hair curves are added)

Also confirmed with 3.3.1.

Short description of error
New hair curves do not render properly (either completely missing or glitch) first time in EEVEE with motion blur enabled. If I render it again they're properly rendered.

While the issue can be easily corrected from user-side, I imagine this would be pretty annoying if I ever tries headless rendering when it comes to Windows.

Exact steps for others to reproduce the error

CurvesMotionBlur.blend1 MBDownload

  • Open the above file.
  • Render.

Revisions and Commits

rB Blender
rB3ac2f15a04c5 GL: Fix incorrect shader state after shader interface creation

Related Objects

Mentioned Here
rBd292d635ea7f: install_deps: Add system libdecor dev package.

Event Timeline

Sun Kim (persun) created this task.Oct 13 2022, 11:33 AM
Omar Emara (OmarSquircleArt) changed the task status from Needs Triage to Needs Information from User.Oct 13 2022, 2:09 PM
Omar Emara (OmarSquircleArt) added a subscriber: Omar Emara (OmarSquircleArt).

I can reproduce the issue in 3.3, but not on the latest master. So maybe this was fixed this week. Can you retry with tomorrows' daily build and see if the issue is fixed?
If yes, we can bisect and add the commit to the LTS list.

Sun Kim (persun) added a comment.Oct 13 2022, 3:11 PM

Actually I tried the lastest build cbe1c1474b16 (only two commits behind the master as far as I can see), and the glitch is still happening.

One thing to note is that this only happens with the first proper render (F12) after you launching Blender. So if you did proper EEVEE render with other file (regardless of enabling motion blur), and then opened this file and render, the glitch won't happen.

Omar Emara (OmarSquircleArt) added a comment.Oct 13 2022, 3:18 PM

I tested the same commit, but I still can't reproduce it.
To clarify, does it happen with only this file? Or can the file be recreated from scratch and be able to show the issue?
If yes, which version did you create this file?

Unknown Object (User) changed the task status from Needs Information from User to Confirmed.Oct 13 2022, 3:48 PM
Unknown Object (User) added a subscriber: Unknown Object (User).

I can confirm rBd292d635ea7f

My uneducated wild guess is that the motion blur uses cached values that should have been computed before. Also if you render it the first time, then open another file, then reopen the first file, the render is correct so it correlates with the blender process. I don't know if thats a surprising fact or not.

Sun Kim (persun) added a comment.Oct 13 2022, 3:57 PM

Yes, the above file was created from scratch in 3.4.

This is from the file where I first discovered the issue. The grass are made of new hair curves. I started this with 3.3 and am working on in 3.4.

I created other test files in 3.3 and 3.4 from scratch, and the glitch happens rather reliably (90% of time).

Omar Emara (OmarSquircleArt) changed the task status from Confirmed to Needs Triage.Oct 13 2022, 4:03 PM

@da.buy I would wait until someone from the triaging team look into this as well.
Also, don't confirm reports without tagging the appropriate module.

Unknown Object (User) added a comment.Oct 13 2022, 4:08 PM

Ok, I'll keep that in mind for the future.
And i should have kept that wild speculation for myself, sorry for that too x)

Simon Thommes (simonthommes) added a subscriber: Simon Thommes (simonthommes).Oct 13 2022, 4:18 PM

Can confirm this issue as well btw, had this in production for a while but couldn't put our finger on what exactly was causing it.
Thanks for reproducing it with a simple file! :)

Unknown Object (User) added a comment.Oct 13 2022, 4:25 PM

I played a little around with it and figured that blender will crash if i hide the GN mod from the viewport and then try to move the curve object

Omar Emara (OmarSquircleArt) changed the task status from Needs Triage to Confirmed.Oct 13 2022, 4:33 PM
Omar Emara (OmarSquircleArt) added projects: EEVEE & Viewport, Nodes & Physics.

I can confirm with a release build. Debug builds seems to work correctly.

Sun Kim (persun) added a comment.EditedOct 13 2022, 4:34 PM
In T101792#1431998, @da.buy wrote:

I played a little around with it and figured that blender will crash if i hide the GN mod from the viewport and then try to move the curve object

I discovered that too but it's actually a new bug introduced between yesterday's build and today's one. Having Scene Time node and playing with modifier visibility crashes Blender. (I'm about to write a report on this one.)

edit: well it's not really about Scene Time node apparently.
edit2: looks like it's fixed with afd30e5e3a77

In T101792#1431995, @Simon Thommes (simonthommes) wrote:

Can confirm this issue as well btw, had this in production for a while but couldn't put our finger on what exactly was causing it.
Thanks for reproducing it with a simple file! :)

Glad to be of help ;)

Clément Foucault (fclem) closed this task as Resolved by committing rB3ac2f15a04c5: GL: Fix incorrect shader state after shader interface creation.Oct 19 2022, 2:41 PM
Clément Foucault (fclem) claimed this task.
Clément Foucault (fclem) added a commit: rB3ac2f15a04c5: GL: Fix incorrect shader state after shader interface creation.
Sun Kim (persun) added a comment.Oct 25 2022, 6:28 AM

I think the fix should be included in 3.3 update too.