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GPencil: Low hardness values always draws yellow
Confirmed, NormalPublicKNOWN ISSUE


System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 451.67

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-08-20 18:28, hash: rBce0bcd5fbf40

Short description of error
Grease Pencil creates yellow transparency with lower hardness values on brush.

Exact steps for others to reproduce the error

  1. Open in 2D Animation mode
  2. Set to a "Dots" brush (eg. Dots Brush) its most noticeably shown there. It happens for the other ones too but this one is most noticeable
  3. Set the Radius to something largish so we can see whats happening (eg 2000px), or zoom in
  4. Draw a circle and you'll be able to see it

It looks like there's a faint yellow tinge transparency which builds up when putting the grease pencil strokes on top of each other.
What it looks like:

Example blend

Basic repro gif

Me shading a ball

Event Timeline

Antonio Vazquez (antoniov) changed the task status from Needs Triage to Confirmed.EditedSun, Aug 23, 2:04 PM

IIRC this is a limitation in the viewport only, but it's not visible in Render.

@Clément Foucault (fclem) was this related to precission in viewport (z-depth IIRC)?

Antonio Vazquez (antoniov) renamed this task from Grease Pencil always draws yellow with lower hardness values to GPencil: Low hardness values always draws yellow.Sun, Aug 23, 2:05 PM

Yes limitation of the R11G11B10 format. We could experiment with the R10G10B10A1 format to see if that helps in this case.

I've found a workaround which may be helpful for debugging. The yellow issue disappears when you add a layer with either "Hard Light" or "Subtract". There doesn't need to be anything in these layers:

Hopefully that helps. Antonio's comment made me curious, so I went looking around.

Antonio Vazquez (antoniov) changed the subtype of this task from "Report" to "Known Issue".Mon, Sep 7, 3:33 PM

Actually, there is a workaround an it's only visible in the viewport, so we can consider it as Know Issue while we found a better solution.