Support DXR in wgpu-hal & naga.

[Vecvec]

Connections
Might provide alternatives for #6727?

Description
This adds support for DXR in wgpu-hal. Also removes an unnecessary feature requirement from ray_cube_compute as this was preventing it from running on DX12. Also adds support for HLSL raytracing because naga didn't have that either.

Testing
this only extends feature support to dx12 so all previous rt tests work.

Checklist

• Run cargo fmt.
• Run taplo format.
• Run cargo clippy. If applicable, add:
  • [n/a] --target wasm32-unknown-unknown
  • [n/a] --target wasm32-unknown-emscripten
• Run cargo xtask test to run tests.
• Add change to CHANGELOG.md. See simple instructions inside file.

[Elabajaba]

I ran the tests for this and it doesn't appear to be working properly? (6800xt/RDNA2 has RT support, I ran $env:WGPU_BACKEND="dx12" then cargo xtask test -- ray_tracing)

        PASS [   0.076s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/0] wgpu_test::ray_tracing::as_build::unbuilt_blas
        PASS [   0.075s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/0] wgpu_test::ray_tracing::scene::acceleration_structure_build_no_index
        PASS [   0.075s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/0] wgpu_test::ray_tracing::as_build::out_of_order_as_build_use
        PASS [   0.076s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/0] wgpu_test::ray_tracing::as_build::out_of_order_as_build
        PASS [   0.089s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/0] wgpu_test::ray_tracing::as_use_after_free::acceleration_structure_use_after_free
        PASS [   0.089s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/1] wgpu_test::ray_tracing::as_build::out_of_order_as_build
        PASS [   0.088s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/0] wgpu_test::ray_tracing::scene::acceleration_structure_build_with_index
        PASS [   0.088s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/1] wgpu_test::ray_tracing::scene::acceleration_structure_build_no_index
        PASS [   0.088s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/1] wgpu_test::ray_tracing::as_build::unbuilt_blas
        PASS [   0.088s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/1] wgpu_test::ray_tracing::as_build::out_of_order_as_build_use
        PASS [   0.100s] wgpu-test::wgpu-test [Unsupported: Features] [Dx12/AMD Radeon RX 6800 XT/0] wgpu_test::ray_tracing::as_build::empty_build
        PASS [   0.095s] wgpu-test::wgpu-test [Unsupported: Features] [Dx12/AMD Radeon RX 6800 XT/1] wgpu_test::ray_tracing::as_build::empty_build
        PASS [   0.100s] wgpu-test::wgpu-test [Unsupported: Features] [Dx12/AMD Radeon RX 6800 XT/0] wgpu_test::ray_tracing::as_create::blas_invalid_vertex_format
        PASS [   0.095s] wgpu-test::wgpu-test [Unsupported: Features] [Dx12/AMD Radeon RX 6800 XT/0] wgpu_test::ray_tracing::as_create::blas_mismatched_index
        PASS [   0.101s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/1] wgpu_test::ray_tracing::scene::acceleration_structure_build_with_index
        PASS [   0.103s] wgpu-test::wgpu-test [Skipped Failure: ADAPTER] [Dx12/AMD Radeon RX 6800 XT/1] wgpu_test::ray_tracing::as_use_after_free::acceleration_structure_use_after_free
        PASS [   0.106s] wgpu-test::wgpu-test [Unsupported: Features] [Dx12/AMD Radeon RX 6800 XT/1] wgpu_test::ray_tracing::as_create::blas_mismatched_index
        PASS [   0.110s] wgpu-test::wgpu-test [Unsupported: Features] [Dx12/AMD Radeon RX 6800 XT/1] wgpu_test::ray_tracing::as_create::blas_invalid_vertex_format

edit: This is probably #6728, I'll try reverting that and see if it works.

edit2: Nope, reverted that and it's now saying [Unsupported: Features] for all of the tests.

edit3: Looks like you need to set the WGPU_DX12_COMPILER environment variable to either dxc or static-dxc for it to work, as it otherwise defaults to FXC. All the ray_tracing tests passed once I set it to either dxc (with the .dlls in my wgpu root dir) or static-dxc.

[cwfitzgerald]

Looks like you need to set the WGPU_DX12_COMPILER environment variable to either dxc or static-dxc for it to work, as it otherwise defaults to FXC. All the ray_tracing tests passed once I set it to either dxc (with the .dlls in my wgpu root dir) or static-dxc.

This should now default to static-dxc after #6730

[Vecvec]

All the ray_tracing tests passed once I set it to either dxc (with the .dlls in my wgpu root dir) or static-dxc.

Since that's on a AMD GPU, that means that this probably does provide an alternative (and may also point to the issue being a wgpu bug vs a AMD bug)

Edit: I'm not sure what GPU generations were being affected though.

[cwfitzgerald]

Same, my 7800xtx passes all tests

[cwfitzgerald]

Both testing issues fixed in #6781 and #6782