Removed Base on SampleLevel in favor of clamp_to_edge. I can update this to be frontend only once decided.
Not sure what triggered the review request, that wasn't intentional.

Thanks!

Not sure what triggered the review request, that wasn't intentional.

We now have a codeowners file with the naga team in it which causes github to automatically request reviews.

Hmm. I actually think it's probably fine to put it in the IR, and make the backends decide how to deal with it. Generally we want the IR to follow WGSL pretty closely. I also think we might get slightly better output this way.

I think adding the Base variant to SampleLevel is actually better than an additional clamp_to_edge field, because the latter raises the question of whether backends should respect clamp_to_edge when SampleLevel is something other than Zero. For example, the change to the GLSL backend in a152303 means that the backend is just ignoring the bool, instead of flagging a problem with the validator.

I would call the variant BaseClampToEdge, though. Again, the IR should generally, roughly, follow WGSL.

Another approach with the same advantages would be to change the Zero variant to Zero { clamp_to_edge: bool }.

@evahop Thanks for implementing this!

If you'd like to post work-in-progress PRs (which we're happy to see), consider marking them as "Draft" when you create the PR. That prevents reviews from being requested.

textureSampleBaseClampToEdge is sugar for:

let half_texel = vec2(0.5) / vec2<f32>(textureDimensions(t));
textureSampleBase(t, s, clamp(coords, half_texel, 1 - half_texel));

We also translate i++ in the frontend to i += 1 IR.

I think frontends should deal with sugar features like these since there is no benefit to have those in the IR.

You could actually make an argument i++ belongs in the IR given the wide availability in the backends but textureSampleBaseClampToEdge has no equivalent in any of the other shading languages.

@jimblandy and I talked about this and we are unsure where this translation belongs yet due to us not supporting texture_external yet (gfx-rs/wgpu#4386). textureSampleBaseClampToEdge can be used with a texture_2d but its main use-case is with a texture_external.

The translation of texture_external & textureSampleBaseClampToEdge will most likely have to happen in the same place (either in the front-end or the back-ends).

I think we should ideally add support for texture_external first or at the same time with textureSampleBaseClampToEdge.

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