Add BGRA8UNORM_STORAGE extension

[jinleili]

Checklist

• Run cargo clippy.
• Run RUSTFLAGS=--cfg=web_sys_unstable_apis cargo clippy --target wasm32-unknown-unknown if applicable.
• Add change to CHANGELOG.md. See simple instructions inside file.

Connections
resolves #3359

Testing
Tested locally on metal, vulkan(--features=vulkan-portability) and dx12 backends:

fn required_features() -> wgpu::Features {
    // wgpu::Features::TEXTURE_ADAPTER_SPECIFIC_FORMAT_FEATURES
    // OR
    wgpu::Features::BGRA8UNORM_STORAGE
}

// ...

let a_texture = device.create_texture(&wgpu::TextureDescriptor {
    format: wgpu::TextureFormat::Bgra8Unorm,
    usage: wgpu::TextureUsages::STORAGE_BINDING,
    ...,
});

let test_tv = a_texture.create_view(&wgpu::TextureViewDescriptor {
    format: Some(wgpu::TextureFormat::Bgra8Unorm),
    ..Default::default()
});

[teoxoy]

Thanks for the PR!

I think we should wait for naga to add support for the texel format before we merge this so that we can test it.

[teoxoy]

On the shader side we need to use Unknown since bgra8unorm is not in this table.

So, we need to check for VK_FORMAT_FEATURE_2_STORAGE_WRITE_WITHOUT_FORMAT_BIT instead.

See KhronosGroup/Vulkan-Docs#2027 (comment) for more background.

[jinleili]

I'm sorry, I don't know how to do the check of VK_FORMAT_FEATURE_2_STORAGE_WRITE_WITHOUT_FORMAT_BIT . Check for FORMAT_FEATURE_2 requires obtaining FormatProperties3 first, but no relevant method was found in ash.

[teoxoy]

Isn't it this structure: https://docs.rs/ash/latest/ash/vk/struct.FormatProperties3.html ?

[jinleili]

Yes, but no way to get it is provided, onlyget_physical_device_format_properties and get_physical_device_format_properties to get FormatProperties FormatProperties2.

[teoxoy]

Hmm, how I think this should work is we call get_physical_device_format_properties2 and pass it a FormatProperties2 with a FormatProperties3 in it's pNext chain.

This is quite convoluted as it requires extensions or specific vulkan versions.

VK_KHR_get_physical_device_properties2 or VK1.1 for the query function and FormatProperties2 structure +
VK_KHR_format_feature_flags2 or VK1.3 for FormatProperties3

[crowlKats]

the feature also needs to be added to https://github.com/gfx-rs/wgpu/blob/master/deno_webgpu/02_idl_types.js#L105-L152

[cwfitzgerald]

Hey this got lost in the PR stack, could you rebase this?

With naga not supporting it yet, how about we land all the infrastructure, but we keep the feature disabled.

[jinleili]

@cwfitzgerald Already rebased, but I'm unsure how to keep the feature disabled.

[cwfitzgerald]

Probably through wgpu-core removing the feature after it queries the features from the device. Can remove it and link back to the naga issue.

[teoxoy]

There is still an unresolved discussion about the Vulkan impl.

[cwfitzgerald]

Dismissing review request due to the above issue.

[nical]

Heads up, I'm continuing the work on this branch: https://github.com/nical/wgpu/tree/bgra8unorm-storage
I'll propose change to this PR or open a new one soon (currently writing a test and hoping it'll work).

[jinleili]

I'm sorry I didn't deal with it for so long, since @nical is already done, it's more appropriate to open a new PR