Normal maps are using incorrect format. about learn-wgpu

[sotrh]

I'm not using normal = normal * 2.0 - 1.0 specifically because I'm using Rgba8UnormSrgb. Doing it this way was suggested by the wgpu guys. Apparently, according to them, Rgba8UnormSrgb outputs colors in the range [-1.0, 1.0], perfect for normals. I'm not an expert on texture formats, but the results look correct to me.

[StarArawn]

You can see the difference here:
https://en.wikipedia.org/wiki/SRGB#/media/File:Cie_Chart_with_sRGB_gamut_by_spigget.png
You lose a lot of range of color by using SRGB. Not to mention it's outside of the typical use case of most engines/tools.

Another article about it:
https://medium.com/@bgolus/generating-perfect-normal-maps-for-unity-f929e673fc57#b86c

[cwfitzgerald]

Rgba8Unorm should still work with a texture2D in shaders, though both Rgba8Unorm and Rgba8UnormSrgb return data as [0.0, 1.0] when sampled as a float. Rgba8Snorm would return values in the range [-1.0, 1.0], though I think to get the proper behavior you should have a Rgba8Unorm texture with manual * 2 - 1 scaling.

[sotrh]

The textures appear washed out when I use Rgba8Unorm and * 2 - 1 scaling.

Sorry about the lack of communication on my part. I've been hunting down running wgpu on Android.

[StarArawn]

I would still use SRGB for the color texture as they are typically made in SRGB color space. When you generate normal maps they are generated in linear color space. It does mean when loading the textures in you have to determine whether it is a normal texture or a color texture. In my engine I use a ron file, but you could just as easily have something like: load_texture(path: Path, is_srgb: boolean)