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Maniphest T94765

Material rendered as black with motion blur and intersecting geometry (was:motion blur bug in geometry nodes)
Confirmed, NormalPublicBUG
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Description

System Information
Operating system: Linux-5.13.0-23-generic-x86_64-with-glibc2.34 64 Bits
Graphics card: Mesa DRI Intel(R) HD Graphics 4600 (HSW GT2) Intel Open Source Technology Center 4.5 (Core Profile) Mesa 21.2.2

Blender Version
Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: rBf1cca3055776
Worked: (newest version of Blender that worked as expected)

Short description of error
when i turned on motion blur seems that exactly when a instance intersects another instance is rendered as black

Exact steps for others to reproduce the error
when motion blur is turned on and two instances instect each other its rendered as black
if frame 27 is rendered u are able to see the bug


domino line.blend1 MBDownload

edit (Martijn) : Renamed to make the problem slightly clearer.
It doesn't happen every time, when rendering with Optix I can reasonably reliably reproduce it.

Event Timeline

Mohammed faihan (faihan) created this task.Jan 9 2022, 12:38 PM
Pratik Borhade (PratikPB2123) updated the task description. (Show Details)Jan 10 2022, 11:00 AM
Pratik Borhade (PratikPB2123) added a subscriber: Pratik Borhade (PratikPB2123).
Germano Cavalcante (mano-wii) changed the task status from Needs Triage to Needs Information from User.Jan 13 2022, 4:18 PM
Germano Cavalcante (mano-wii) added a subscriber: Germano Cavalcante (mano-wii).

I cannot reproduce this with either the latest stable or current development versions of Blender:

Please try the latest daily build: https://builder.blender.org/download/

Go to File → Defaults → Load Factory Settings and then load your file to see if you still can reproduce this issue.

If the problem persists, please give us more clear instructions on how to reproduce it from scratch.

Mohammed faihan (faihan) added a comment.Jan 13 2022, 7:55 PM

Now even with the same version the error is gone, with the exact same file these errors also occurred to me before and sometimes after re rendering it disappears ,without even changing anything. seems it only occurs with geometry nodes on linux

Martijn Versteegh (Baardaap) added a subscriber: Martijn Versteegh (Baardaap).Jan 21 2022, 8:45 PM

Can confirm on Ubuntu Focal Nvidia GeForce RTX 2060 SUPER .

Got it once out of 5 renders on Optix. Didn't succed in reproducing on CUDA or CPU.

Martijn Versteegh (Baardaap) renamed this task from motion blur bug in geometry nodes to Material rendered as black with motion blur and intersecting geometry (was:motion blur bug in geometry nodes).EditedJan 21 2022, 10:21 PM
Martijn Versteegh (Baardaap) changed the task status from Needs Information from User to Confirmed.
Martijn Versteegh (Baardaap) updated the task description. (Show Details)
Martijn Versteegh (Baardaap) added a project: Render & Cycles.
Martijn Versteegh (Baardaap) added a subscriber: Brecht Van Lommel (brecht).

It's a nasty heisenbug, but I *can* reproduce it so I set it as confirmed.

edit: this was the daily build of today (jan 21)

Brecht Van Lommel (brecht) changed the subtype of this task from "Report" to "Bug".Feb 4 2022, 7:14 PM