Gpencil stroke yellowish color shift caused by framebuffer attached with GPU_R11F_G11F_B10F texture. #94253

New Issue

Ghost · 2021-12-19T16:49:04+01:00

Ghost commented

2021-12-19 16:49:04 +01:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3060 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 497.09

Blender Version
Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: f1cca30557
Worked: (newest version of Blender that worked as expected)

Short description of error
Yellowish color shift is caused by using framebuffer attached with GPU_R11F_G11F_B10F texture. Every single dots lost a little bit blue precision caused by texture type and make the whole stroke tints yellow after blending.

Fix method (Maybe?)
source\blender\draw\engines\gpencil\gpencil_engine.c::689 change texture format into GPU_RGBA16F. But there are still several places are using GPU_R11F_G11F_B10F. I don't know whether or not to we should change them.

Exact steps for others to reproduce the error
Open blender with default 2D animation settings. Change brush into airbrush and strength 0.1. Draw on canvas. colorbug.blend

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3060 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 497.09 **Blender Version** Broken: version: 3.0.0, branch: master, commit date: 2021-12-02 18:35, hash: `f1cca30557` Worked: (newest version of Blender that worked as expected) ![gpencilColorBug.png](https://archive.blender.org/developer/F12763799/gpencilColorBug.png) **Short description of error** Yellowish color shift is caused by using framebuffer attached with `GPU_R11F_G11F_B10F` texture. Every single dots lost a little bit blue precision caused by texture type and make the whole stroke tints yellow after blending. **Fix method (Maybe?)** `source\blender\draw\engines\gpencil\gpencil_engine.c::689` change texture format into `GPU_RGBA16F`. But there are still several places are using `GPU_R11F_G11F_B10F`. I don't know whether or not to we should change them. **Exact steps for others to reproduce the error** Open blender with default 2D animation settings. Change brush into airbrush and strength 0.1. Draw on canvas. [colorbug.blend](https://archive.blender.org/developer/F12763766/colorbug.blend)

Antonio Vazquez commented

2021-12-19 17:04:34 +01:00

Added subscribers: @fclem, @antoniov

Antonio Vazquez commented

2021-12-19 17:04:34 +01:00

@fclem what do you think?

Germano Cavalcante commented

2022-01-18 21:14:34 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2022-01-18 21:14:34 +01:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Germano Cavalcante commented

2022-01-18 21:14:34 +01:00

I can confirm the yellowish color, which is not seen in the render (with F12) because this one is apparently using GPU_RGBA16F and not GPU_R11F_G11F_B10F.

Maybe we could use GPU_RGB10_A2 to have a more balanced ratio between R, G and B channels and still keep the same memory size?

At first glance it doesn't seem ideal to have a different resolution for the blue channel.

I can confirm the yellowish color, which is not seen in the render (with F12) because this one is apparently using `GPU_RGBA16F` and not `GPU_R11F_G11F_B10F`. Maybe we could use `GPU_RGB10_A2` to have a more balanced ratio between R, G and B channels and still keep the same memory size? At first glance it doesn't seem ideal to have a different resolution for the blue channel.

Clément Foucault commented

2022-01-18 21:56:08 +01:00

IIRC, GPU_RGB10_A2 does not use the same blending capabilities as GPU_R11F_G11F_B10F which does the blending in unclamped floating points (first one blends in [0..1], the other [0..MAX_FLT]). But I'm not 100% sure about this.

And we now have shaded (lit) gpencils objects in the gpencil engines that needs correct unbounded linear space color blending before the tone-mapping step. This is why we keep GPU_R11F_G11F_B10F. using GPU_RGBA16F really slows down quickly on complex scene.

IIRC, `GPU_RGB10_A2` does not use the same blending capabilities as `GPU_R11F_G11F_B10F` which does the blending in unclamped floating points (first one blends in [0..1], the other [0..MAX_FLT]). But I'm not 100% sure about this. And we now have shaded (lit) gpencils objects in the gpencil engines that needs correct unbounded linear space color blending before the tone-mapping step. This is why we keep `GPU_R11F_G11F_B10F`. using `GPU_RGBA16F` really slows down quickly on complex scene.

Philipp Oeser removed the

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Gpencil stroke yellowish color shift caused by framebuffer attached with GPU_R11F_G11F_B10F texture. #94253

Gpencil stroke yellowish color shift caused by framebuffer attached with `GPU_R11F_G11F_B10F` texture. #94253