vulkano panicked when using with rust-gpu

[SSSxCCC]

• Version of vulkano: 0.34.1
• Version of rust-gpu: 0.9
• OS: Windows10
• GPU (the selected PhysicalDevice): Intel Iris Xe Graphics
• GPU Driver: 31.0.101.5522
• Upload of a reasonably minimal complete main.rs file that demonstrates the issue:

rust-gpu shader:

#![no_std]

use spirv_std::{glam::{vec4, Vec2, Vec4}, spirv};

#[spirv(vertex)]
pub fn main_vs(
    #[spirv(position, invariant)] out_pos: &mut Vec4,
    position: Vec2,
) {
    *out_pos = position.extend(0.0).extend(1.0);
}

#[spirv(fragment)]
pub fn main_fs(output: &mut Vec4) {
    *output = vec4(1.0, 0.0, 0.0, 1.0);
}

vulkano code:

        const SHADER: &[u8] = include_bytes!(env!("minimal_shader.spv"));
        let shader_code = SHADER
            .chunks(4)
            .map(|c| u32::from_le_bytes([c[0], c[1], c[2], c[3]]))
            .collect::<Vec<_>>();

        let shader_module = unsafe {
            ShaderModule::new(
                context.device().clone(),
                ShaderModuleCreateInfo::new(&shader_code),
            )
        }
        .unwrap();

        let vs = shader_module.entry_point("main_vs").unwrap();
        let fs = shader_module.entry_point("main_fs").unwrap();

        let vertex_input_state = MyVertex::per_vertex()
            .definition(&vs.info().input_interface) // panicked here
            .unwrap();

MyVertex:

#[derive(BufferContents, Vertex)]
#[repr(C)]
struct MyVertex {
    #[format(R32G32_SFLOAT)]
    position: [f32; 2],
}

Issue

thread 'main' panicked at 'called Option::unwrap() on a None value', C:\Users\SxC.cargo\registry\src\index.crates.io-6f17d22bba15001f\vulkano-0.34.1\src\pipeline\graphics\vertex_input\definition.rs:45:46

[marc0246]

The unwrap was fixed in #2487. If you want to use vulkano's reflection capabilities, such as creating a matching vertex input state or generating structs using vulkano-shaders, you have to provide the necessary reflection information, that is, SpirvMetadata::NameVariables. You haven't provided the compilation code but I assume you haven't done this. As such, this working as inteded even in your version, minus the panic.

[SSSxCCC]

I add SpirvMetadata::NameVariables in build.rs and this issue is fixed. Thank you so much!

use spirv_builder::{MetadataPrintout, SpirvBuilder, SpirvMetadata};
use std::error::Error;

fn main() -> Result<(), Box<dyn Error>> {
    SpirvBuilder::new("minimal-shader", "spirv-unknown-vulkan1.2")
        .spirv_metadata(SpirvMetadata::NameVariables) // this fix this issue
        .print_metadata(MetadataPrintout::Full)
        .build()?;

    Ok(())
}

[marc0246]

No problem! (Though I think full is excessive?)

[SSSxCCC]

I just started to learn to use rust-gpu, MetadataPrintout::Full is copied from somewhere else. I just delete '.print_metadata(MetadataPrintout::Full)' and the code also works fine, thanks again!

[marc0246]

I'm not 100% sure either because I don't actively use Rust-GPU, but I think you need MetadataPrintout::DependencyOnly. @Firestar99 could you be a darling and jump in here?

[SSSxCCC]

I just found that print_metadata is set to MetadataPrintout::Full in SpirvBuilder::new. So deleting '.print_metadata(MetadataPrintout::Full)' changes nothing.

I tried to change MetadataPrintout::Full to MetadataPrintout::DependencyOnly, but this resulted in a compilation error:

error: environment variable `minimal_shader.spv` not defined at compile time
   --> minimal\src\triangle_renderer.rs:132:46
    |
132 |         const SHADER: &[u8] = include_bytes!(env!("minimal_shader.spv"));
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: use `std::env::var("minimal_shader.spv")` to read the variable at run time
    = note: this error originates in the macro `env` (in Nightly builds, run with -Z macro-backtrace for more info)

[Firestar99]

I've made a small sample project on how to integrate vulkano and rust-gpu, feel free to reference: https://github.com/Firestar99/rust-gpu-vulkano-example

The build script I'm using configures spirv-builder like this:

SpirvBuilder::new(crate_path, TARGET)
        .multimodule(true)
        // this needs at least NameVariables for vulkano to like the spv, but may also be Full
        .spirv_metadata(SpirvMetadata::NameVariables)
        .print_metadata(MetadataPrintout::DependencyOnly)
        .build()?;

• multimodule so that every shader has a separate spv file, it will work without, but almost all tooling expects one shader per spv file. And shader! codegen may generate the same struct multiple times resulting in compile errors, if you didn't disable it (currently only master).
• print_metadata: if you use a build script and you don't emit any cargo::rerun-if-changed=./path, cargo will only rerun your build script if the script or the contents of src changed. Which means if you only change your shaders, or dependencies that only your shaders depend upon, your shaders won't be recompiled and you'll be confused on why yout changes don't do anything. MetadataPrintout::DependencyOnly makes rust-gpu emit this rerun metadata for cargo on it's own, without you having to care for it at all, and you'll always have up-to-date shaders.

Unfortunately the rust-gpu docs are a bit lacking, especially when you're trying to get started.

[Firestar99]

Also feel free to steal the codegen of my main project, which generates a single .rs file containing each shader entry point as a separate shader! macro invocation with the correct *.spv path, all of them organized in the same mod structure as your shader crate. But I haven't gotten around to clean it up enough to release it publicly, though that may happen in a few months as I want to publish a bindless API for rust-gpu and vulkano (potentially wgpu as well?). https://gitlab.com/spacegamedev/space-rust/-/tree/master/vulkano-bindless/vulkano-bindless-shader-builder?ref_type=heads