The colors of the vertices do not correspond to the values in which I paint them with vertex paint. #91759

New Issue

Alexey · 2021-09-27T22:19:33+02:00

Alexey commented

2021-09-27 22:19:33 +02:00

System Information
Operating system: Windows-10-10.0.14393-SP0 64 Bits
Graphics card: GeForce GTX 1050/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.38

Blender Version
Broken: version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: 02948a2cab
Worked: (newest version of Blender that worked as expected)

Short description of error
the vertex color values that I get from the vertices in the shader editor node called "vertex_color" do not correspond to the values that I write there using vertex painting.

Exact steps for others to reproduce the error

[Please describe the exact steps needed to reproduce the issue]
Set the viewport mode to render or material preview. And change the inputs from the manual value to the value taken from vertex color. As you can see, the values themselves should not differ, but the color change.

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

Perhaps this is due to this issue https://developer.blender.org/D10956, but I want to say that we then need the ability to convert from one color space to another.
Because I use a blender to create game models and would like to use vertex colors to mix materials. But I can't, because it doesn't correspond to the colors and values that I enter. And it will not match what I will see in the game.
In addition, I enter specific values using the color wheel and sliders. And I expect to get them unchanged. That would be logical.

**System Information** Operating system: Windows-10-10.0.14393-SP0 64 Bits Graphics card: GeForce GTX 1050/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.38 **Blender Version** Broken: version: 2.92.0, branch: master, commit date: 2021-02-24 16:25, hash: `02948a2cab` Worked: (newest version of Blender that worked as expected) **Short description of error** the vertex color values that I get from the vertices in the shader editor node called "vertex_color" do not correspond to the values that I write there using vertex painting. **Exact steps for others to reproduce the error** ![vertex_color.gif](https://archive.blender.org/developer/F10637884/vertex_color.gif) [Please describe the exact steps needed to reproduce the issue] Set the viewport mode to render or material preview. And change the inputs from the manual value to the value taken from vertex color. As you can see, the values themselves should not differ, but the color change. [Based on the default startup or an attached .blend file (as simple as possible)] [vertex_color_error.blend](https://archive.blender.org/developer/F10637862/vertex_color_error.blend) Perhaps this is due to this issue https://developer.blender.org/D10956, but I want to say that we then need the ability to convert from one color space to another. Because I use a blender to create game models and would like to use vertex colors to mix materials. But I can't, because it doesn't correspond to the colors and values that I enter. And it will not match what I will see in the game. In addition, I enter specific values using the color wheel and sliders. And I expect to get them unchanged. That would be logical.

Alexey commented

2021-09-27 22:19:33 +02:00

Added subscriber: @lexpartizan

blender-admin commented

2021-09-27 22:19:33 +02:00

#92082 was marked as duplicate of this issue

blender-admin commented

2021-09-27 22:19:33 +02:00

#90223 was marked as duplicate of this issue

Germano Cavalcante commented

2021-09-28 18:54:06 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-09-28 18:54:06 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Germano Cavalcante commented

2021-09-28 18:54:06 +02:00

Thanks for the report,

I'm not familiar with this area, so for me it also seems to be a bug.

One thing to keep in mind first is that loop colors are stored in byte channels {255, 255, 255, 255}.
So it's impossible to have an exact {0.9, 0.9, 0.9, 1.0} value.
The closest would be {0.90196078431, 0.90196078431, 0.90196078431, 1.0} which corresponds to {230, 230, 230, 255}.

Reading the value of Mesh->mloopcol, they show {230, 230, 230, 255} which corresponds to 0.9 in RGB linear space.
But apparently Cycles, Spreadsheet and Draw Manager consider mloopcol to be sRGB and not the linear RGB.
The mloopcol values are converted to float using BLI_color_from_srgb_table[230].

So apparently Vertex Paint is forgetting to convert the color in the Color Picker to sRGB.

This appears to be a bug.

Thanks for the report, I'm not familiar with this area, so for me it also seems to be a bug. One thing to keep in mind first is that loop colors are stored in byte channels `{255, 255, 255, 255}`. So it's impossible to have an exact `{0.9, 0.9, 0.9, 1.0}` value. The closest would be `{0.90196078431, 0.90196078431, 0.90196078431, 1.0}` which corresponds to `{230, 230, 230, 255}`. Reading the value of `Mesh->mloopcol`, they show `{230, 230, 230, 255}` which corresponds to `0.9` in `RGB` linear space. But apparently `Cycles`, `Spreadsheet` and `Draw Manager` consider `mloopcol` to be `sRGB` and not the linear `RGB`. The `mloopcol` values are converted to `float` using `BLI_color_from_srgb_table[230]`. So apparently Vertex Paint is forgetting to convert the color in the Color Picker to `sRGB`. This appears to be a bug.

Alexey commented

2021-09-28 19:56:37 +02:00

As far as I understand you, the colors themselves in the vertices are quite correct. Just a blender using the vertex_color node produces a non-linear sRGB. I am glad to hear that.
Accuracy is not so important, small differences are quite acceptable, but here the differences are visible to the naked eye and they change from value to value. The problem is also that very often (in my case) vertex color is used not only for the image of colors, where differences in color have a visual component, but also as masks or maps of materials, where compliance matters. I use this to mix materials, however, due to such transformations, I get a very unexpected result, different from what will be in the game, for example.

As far as I understand you, the colors themselves in the vertices are quite correct. Just a blender using the vertex_color node produces a non-linear sRGB. I am glad to hear that. Accuracy is not so important, small differences are quite acceptable, but here the differences are visible to the naked eye and they change from value to value. The problem is also that very often (in my case) vertex color is used not only for the image of colors, where differences in color have a visual component, but also as masks or maps of materials, where compliance matters. I use this to mix materials, however, due to such transformations, I get a very unexpected result, different from what will be in the game, for example.

Germano Cavalcante commented

2021-09-29 17:32:36 +02:00

Added subscribers: @Consta, @EAW, @scurest

Germano Cavalcante commented

2021-10-11 20:55:49 +02:00

Added subscriber: @barakooda

Philipp Oeser removed the

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The colors of the vertices do not correspond to the values in which I paint them with vertex paint. #91759