Texture SRV Component Mapping

[Hydr10n]

Default component mapping is fine in most cases, but, for example, when a texture format is actually single channel, and shader always treats textures as Texture2D<float4>, the sampled value is float4(r, 0, 0, 0) instead of float4(r, r, r, r), it would be convenient if add component mapping in TextureView or just create SRV in backends like this:

mapping = DEFAULT_SHADER_COMPONENT_MAPPING;
if (GetNumComponents(format) == 1) {
    mapping = ENCODE_SHADER_COMPONENT_MAPPING(R, R, R, R);
}

[dzhdanNV]

Feel free to throw a shoe at me: the only reason why it hasn't been implemented yet, it's because D3D11 doesn't support it. It's not a problem to diverge more and add "component mapping" feature with a deviceDesc.features.componentMapping cap.

[Hydr10n]

I didn't realize D3D11 doesn't support it until now. Shader code can be cleaner and faster without special branching or permutations for different texture swizzles if simply enable component mapping in texture view. D3D12 and VK are the modern GAPIs for higher performance, so it's worth adding features.componentMapping.

[dzhdanNV]

Will do, but I'm busy for a few days.