Bump map texture painting in 3d viewport applies gamma correction to 32-bit float noncolor image data. #82818

New Issue

Paul Schubert · 2020-11-18T16:35:26+01:00

Paul Schubert commented

2020-11-18 16:35:26 +01:00

System Information
Operating system: NA (Windows-10-10.0.18362-SP0 64 Bits, Darwin)
Graphics card: NA (GeForce GTX 470/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 391.35, AMD Radeon HD 6970M 4.1 ATI-1.68.25)

Blender Version
Broken: version: 2.90.1, 2.92.0 Alpha, branch: master, commit date: 2020-11-18 13:26, hash: f132d74c7d
Worked: (newest version of Blender that worked as expected)

Short description of error
When texture painting a float non color image, the 3D viewport uses a different mix algorithm than the one used on byte images in the 3D viewport, and floats and bytes in the Image Editor.

Mix additive ?	Byte	Float
Image Editor	Yes	Yes
3d Viewport	Yes	No

Exact steps for others to reproduce the error

Problem with texture painting bump maps. The image above shows two drawn curves. The left curve was drawn in the image editor, the right curve was drawn in the 3D viewport. Brush color is set to (r,g,b)=(0.6,0.6,0.6). The image texture used for the bump map was generated by the brush tool which creates a noncolor image set to 0.5. The problem occurs when specifying a 32-bit float for that image.

You can open the 2 following .blend files, and try painting a stroke in both the 3D viewport and the Image editor.

T82818_texturepaint_mix_byte.blend

T82818_texturepaint_mix_float.blend

system-info.txt

**System Information** Operating system: **NA** (Windows-10-10.0.18362-SP0 64 Bits, Darwin) Graphics card: **NA** (GeForce GTX 470/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 391.35, AMD Radeon HD 6970M 4.1 ATI-1.68.25) **Blender Version** Broken: version: 2.90.1, 2.92.0 Alpha, branch: master, commit date: 2020-11-18 13:26, hash: `f132d74c7d` Worked: (newest version of Blender that worked as expected) **Short description of error** When texture painting a float non color image, the `3D viewport` uses a different `mix` algorithm than the one used on byte images in the 3D viewport, and floats and bytes in the `Image Editor`. | **Mix additive ?** | Byte | Float | | -- | -- | -- | | Image Editor | Yes | Yes | | 3d Viewport | Yes | No | **Exact steps for others to reproduce the error** ![Screen Shot 2020-11-17 at 10.10.26 AM.png](https://archive.blender.org/developer/F9317443/Screen_Shot_2020-11-17_at_10.10.26_AM.png) Problem with texture painting bump maps. The image above shows two drawn curves. The left curve was drawn in the image editor, the right curve was drawn in the 3D viewport. Brush color is set to (r,g,b)=(0.6,0.6,0.6). The image texture used for the bump map was generated by the brush tool which creates a noncolor image set to 0.5. The problem occurs when specifying a 32-bit float for that image. You can open the 2 following .blend files, and try painting a stroke in both the 3D viewport and the Image editor. ![T82818_texturepaint_mix_byte.png](https://archive.blender.org/developer/F9317625/T82818_texturepaint_mix_byte.png) [T82818_texturepaint_mix_byte.blend](https://archive.blender.org/developer/F9317633/T82818_texturepaint_mix_byte.blend) ![T82818_texturepaint_mix_float.png](https://archive.blender.org/developer/F9317627/T82818_texturepaint_mix_float.png) [T82818_texturepaint_mix_float.blend](https://archive.blender.org/developer/F9317635/T82818_texturepaint_mix_float.blend) --- [system-info.txt](https://archive.blender.org/developer/F9317432/system-info.txt)

Paul Schubert commented

2020-11-18 16:35:26 +01:00

Added subscriber: @pcschubert