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When "Motion Blur" is turned on, materials look distorted in Viewport
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Description

System Information
Operating system: Windows 10 x64
Graphics card: Nvidia GTX 1060 (laptop)

Blender Version
Broken: 2.80, 91a155833e59, blender 2.8, 2019-01-07

Short description of error
BEHAVIOR
When using Principled BSDF to make a metallic material and then enabling Motion Blur, seeing the rendered view in viewport shows heavy distortions in material appearance (renders out fine, though). Disabling or unchecking either "Motion Blur" or "Screen Space Reflections" in render settings fixes the issue and the distortions disappear.

EXPECTED BEHAVIOR
When in rendered mode in viewport, that material would appear without distortions regardless of whether motion blur is checked or not.

SCREENSHOT EXAMPLES:
Here is a screenshot example with motion blur enabled: https://www.dropbox.com/s/hd7t29ok6hwvkrc/scene%20with%20motion%20blur.jpg?dl=0
And here is a screenshot example with motion blur disabled: https://www.dropbox.com/s/bpd29dgsj4jr5kh/scene%20without%20motion%20blur.jpg?dl=0

Exact steps for others to reproduce the error

  1. Create new general blender project
  2. Go to default cube's Principled BSDF material settings and make metallic by turning up metallic parameter to 1.0
  3. Enable "Motion Blur" and "Screen Space Reflections" in render settings
  4. Press "Z" key and switch viewport mode to "Rendered", then press "NUMPAD 0" key to look through camera

Details

Type
Bug

Event Timeline

This comment was removed by TravLR (TravLR).
TravLR (TravLR) updated the task description. (Show Details)
TravLR (TravLR) updated the task description. (Show Details)
Jacques Lucke (JacquesLucke) triaged this task as Needs Information from User priority.

Thanks for the report.
Could you upload the screenshots directly here instead of linking to dropbox, please?
Also, could you prepare a simple .blend file that clearly shows the issue?

I'll get to work on the .blend file -- been really busy in my day job.

I tried to attach the screenshots in the original post, but didn't see a button where I could attach the files. I just now read in faded gray, below, where it says "Please fill in all requested information. Use drag and drop to attach files." So now I know I can attach screenshots that way. (I would suggest adding an "attach" button as well for user-friendliness and convenience to the top toolbar of this post editor, IMO.)

Screenshots.

Included is a sample .blend project file (toggle either the "Screen Space Reflections" or the "Motion Blur" checkboxes in the Render settings to see example of bug):

Jacques Lucke (JacquesLucke) raised the priority of this task from Needs Information from User to Confirmed, Medium.Jan 22 2019, 10:58 AM