check sampler type in as_bind_group derives

[robtfm]

Objective

currently if we use an image with the wrong sampler type in a material, wgpu panics with an invalid texture format. turn this into a warning and fail more gracefully.

Solution

the expected sampler type is specified in the AsBindGroup derive, so we can just check the image sampler is what it should be.

i am not totally sure about the mapping of image sampler type to #[sampler(type)], i assumed:

    "filtering" => [ TextureSampleType::Float { filterable: true } ],
    "non_filtering" => [
        TextureSampleType::Float { filterable: false },
        TextureSampleType::Sint,
        TextureSampleType::Uint,
    ],
    "comparison" => [ TextureSampleType::Depth ],

[afonsolage]

I've run into this issue and I agree this shouldn't be a hard error, since it's totally recoverable, by just changing the sample or data format.

[alice-i-cecile]

@robtfm I'll merge this once the merge conflicts are resolved :)

[robtfm]

apologies, i destroyed the history trying to rebase...

[alice-i-cecile]

That's git for you ;) No worries, it gets squashed to the PR level anyways.