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Maniphest T69930

Workbench Transparent Film Anti-Aliasing White Contour
Closed, DuplicatePublicKNOWN ISSUE
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Description

example.blend809 KBDownload
System Information
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: GeForce GTX 1050/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 391.35

Blender Version
Broken: version: 2.81 (sub 11), branch: master, commit date: 2019-09-15 18:34, hash: rBb043bef000e9
Worked: (optional)

Short description of error
Workbench transparent film render adds a weird semi-transparent white contour on edges of alpha channel, if background isn't 100% black, and Anti-aliasing enabled.

Exact steps for others to reproduce the error

  1. For startup file
  2. Choose workbench engine, enable transparent film.
  3. Render with transparent background.
  4. In render workspace choose "Color" instead of "Color and Alpha" to see problem clearly.
  1. For example file:
  2. Press F12 for render

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

Event Timeline

Sam (NinKorr) created this task.Sep 16 2019, 9:35 AM
Sam (NinKorr) renamed this task from Workbench Transparent Film Contour to Workbench Transparent Film Anti-Aliasing White Contour.Sep 16 2019, 9:48 AM
Sam (NinKorr) updated the task description. (Show Details)
Sam (NinKorr) updated the task description. (Show Details)Sep 16 2019, 10:22 AM
Sam (NinKorr) updated the task description. (Show Details)Sep 19 2019, 12:52 PM
Germano Cavalcante (mano-wii) assigned this task to Jeroen Bakker (jbakker).Sep 30 2019, 3:56 PM
Germano Cavalcante (mano-wii) lowered the priority of this task from 90 to 50.
Germano Cavalcante (mano-wii) added subscribers: Jeroen Bakker (jbakker), Germano Cavalcante (mano-wii).

@Jeroen Bakker (jbakker), is this a known limitation of workbench rendering?

Jeroen Bakker (jbakker) added a comment.Sep 30 2019, 4:49 PM

Seems like we need to finetune this.
Workbench was never designed to be a renderer, so we were able to hide some of these artifacts. But I agree we should check what is causing this and find a solution.

Jeroen Bakker (jbakker) added a comment.Oct 1 2019, 9:41 AM

Ah, Seems like a display issue. The color values are correct, but seems like that when displaying the buffer is set or assumed to be pre-multiplied, but in fact workbench outputs straight alpha.
This makes all alpha values other than 1.0 and 0.0 displayed incorrectly.

Sam (NinKorr) added a comment.EditedOct 1 2019, 8:19 PM

I just realised... Is it compositor bug?
Looks like non-monochrome alpha breaks even Eevee renders. Alpha from other image/view layer breaks color data, same glitch. Outline stays here after export. Same mixing in other software gives correct result.

Philipp Oeser (lichtwerk) added projects: Render Pipeline, Compositing.Nov 20 2019, 3:55 PM
Jeroen Bakker (jbakker) lowered the priority of this task from 50 to Low.Dec 15 2019, 12:03 AM
Dalai Felinto (dfelinto) removed Jeroen Bakker (jbakker) as the assignee of this task.Dec 23 2019, 1:50 PM
Dalai Felinto (dfelinto) added a project: Tracker Curfew.
Clément Foucault (fclem) changed the subtype of this task from "Report" to "Known Issue".Jan 17 2020, 8:44 PM
Clément Foucault (fclem) removed a project: Tracker Curfew.
Clément Foucault (fclem) added a subscriber: Clément Foucault (fclem).

This is a viewer bug. Not a bug in workbench.

Clément Foucault (fclem) closed this task as a duplicate of T52680: Alpha difference Viewport/F12 .Jan 17 2020, 8:45 PM