Writing to an Image with format = r32f: f32 does not implement Vector<f32, 1>

[Algorhythm-sxv]

I am trying to port a 2D FVM simulation into Rust-GPU and using type Tex = Image!(2D, format = r32f, sampled = false); to store 2D arrays of f32. Image::read happily returns a single f32, but Image::write won't accept a single f32 since it's expecting a type that implements the spirv Vector trait, and there is no implementation of Vector<f32, 1> for f32. Passing in a Vec2 gets rid of the compiler error, as well as creating a Vec1(f32) newtype and implementing the traits for it (curse you orphan rule!), but these feel like workarounds that shouldn't be necessary. I haven't gotten the shader to a runnable state yet to test.

• Am I using the right sort of image/buffer for this use case? Or am I unintentionally abusing Image?
• Is there something I'm missing to be able to write f32s into a monochrome image? Or is a workaround like this necessary for now given the missing implementation of Vector?

[Firestar99]

(Sorry we all missed your question)

You are using it correctly, this is a bug on our side, the function declaration should accept f32 values. I've made a PR #474 to fix this issue.

Workaround1: image.write(texel_coord, Vec2::new(value, 0.)) should work as the image write intrinsic will just ignore any higher component counts than the image supports. (untested)

Workaround2: I also have a project that writes to storage images from compute shaders, but I'm using spirv_std::image::StorageImage2d, which is defined as Image!(2D, type=f32, sampled = false) using type instead of format. This declares the image as a f32 image without declaring the component count, so all read / sample ops will return a Vec4 with the higher components being zeroed out or undef, not sure. That requires the capability StorageImageWriteWithoutFormat / StorageImageReadWithoutFormat and potentially StorageImageExtendedFormats for certain formats, set it with SpirvBuilder::capability in your build script.