image attribute has no arguments in storage_class.rs

[adrianisuru]

My goal is to recreate the shader below in rust.

// https://vulkano.rs/guide/mandelbrot
#version 450

 layout(local_size_x = 8, local_size_y = 8, local_size_z = 1) in;

 layout(set = 0, binding = 0, rgba8) uniform writeonly image2D img;

 void main() {
     vec2 norm_coordinates = (gl_GlobalInvocationID.xy + vec2(0.5)) / vec2(imageSize(img));

     vec2 c = (norm_coordinates - vec2(0.5)) * 2.0 - vec2(1.0, 0.0);

     vec2 z = vec2(0.0, 0.0);
     float i;
     for (i = 0.0; i < 1.0; i += 0.005) {
         z = vec2(
         z.x * z.x - z.y * z.y + c.x,
         z.y * z.x + z.x * z.y + c.y
         );

         if (length(z) > 4.0) {
             break;
         }
     }

     vec4 to_write = vec4(vec3(i), 1.0);
     imageStore(img, ivec2(gl_GlobalInvocationID.xy), to_write);
}

Here is the code I have so far.

#![cfg_attr(
target_arch = "spirv",
no_std,
feature(register_attr),
register_attr(spirv)
)]

extern crate spirv_std;

#[cfg(not(target_arch = "spirv"))]
#[macro_use]
pub extern crate spirv_std_macros;

use spirv_std::storage_class::{Input, Image};
use spirv_std::glam::{Vec2, Vec3, Vec4};

const BAILOUT: i32 = 200;

#[allow(unused_attributes)]
#[spirv(gl_compute(local_size_x = 8, local_size_y = 8, local_size_z = 1))]
pub fn main(
    #[spirv(global_invocation_id)] gid: Input<Vec3>,
    #[spirv(image(dim="Dim2D", depth=1, arrayed=0, multisampled=0, sampled=0, image_format="Rgba8", access_qualifier="WriteOnly"))] img: &mut Image<Vec4>
) {
    let gid = gid.load();
    let norm_coordinates = (gid.truncate() + Vec2::new(0.5, 0. )) / Vec2::new(1024., 1024.);
    let  c = (norm_coordinates - Vec2::new(0.5, 0.))*2. - Vec2::new(1., 0.);
    let mut z = Vec2::zero();
    let mut i = 0i32;
    while i < BAILOUT {
        z = Vec2::new(z.x*z.x - z.y*z.y + c.x, 2.*z.x*z.y + c.y);
        if z.length() > 4. {
            break;
        }
        i = i + 1;
    };
    let to_write = Vec4::new(i as f32, 0., 0., 1.);
    img.store(to_write);
}

Through trial and error I found that the image macro requires many arguments.

#[spirv(image(dim="Dim2D", depth=1, arrayed=0, multisampled=0, sampled=0, image_format="Rgba8", access_qualifier="WriteOnly"))]

When I compile this shader with my build script, I get an error.

use spirv_builder::SpirvBuilder;
use std::error::Error;
use std::boxed::Box;
fn main() -> Result<(), Box<dyn Error>> {
    SpirvBuilder::new("shader")
        .spirv_version(1, 0)
        .build()?;
    Ok(())
}

$ cargo build
.
.
.
 error: image attribute must have arguments
     --> /home/adrianisuru/.cargo/git/checkouts/rust-gpu-e0a37a82a46176e6/1454fe3/crates/spirv-std/src/storage_class.rs:128:13
      |
  128 |     #[spirv(image)] writeable storage_class Image;
      |             ^^^^^
.
.
.

It seems this error occurs because in storage_class.rs, image has no arguments. Is it that image always requires many arguments or does the error in storage_class.rs occur for some other reason, say, something I've done incorrectly in my code?

Any help is appreciated.

[khyperia]

Oh fun, didn't notice there was a storage class called image, no idea what the heck that does.

What you want here is, roughly (doing this off the top of my head):

use spirv_std::{storage_class::UniformConstant, textures::Image2d};
pub fn main(
    #[spirv(global_invocation_id)] gid: Input<Vec3>,
    mut img: UniformConstant<Image2d>
) {
...
}

However, we have no support for OpImageWrite yet, so the shader can't be translated right now. Not sure if there may be other unimplemented things, too.

[XAMPPRocky]

Oh fun, didn't notice there was a storage class called image, no idea what the heck that does.

According to the spec, it's just for storing image memory.

[khyperia]

Yeah, I saw that, but like... what does "image memory" mean? clearly not storing an image, because that's UniformConstant? aaa

[adrianisuru]

Thanks. I guess then what I want to draw attention to is this:

rust-gpu/crates/spirv-std/src/storage_class.rs

Line 128 in 1454fe3

#[spirv(image)] writeable storage_class Image;

In storage_class.rs the image macro is used without any arguments, but in symbols.rs there is code to check for, and error, when the image macro has no arguments.

rust-gpu/crates/rustc_codegen_spirv/src/symbols.rs

Line 546 in 1454fe3

.span_err(attr.span(), "image attribute must have arguments");

It seems inconsistent.

[khyperia]

yeah, it's because there's a name collision we didn't notice before, the no-argument one is defined here. we need to rename one of them.

rust-gpu/crates/rustc_codegen_spirv/src/symbols.rs

Line 168 in 1454fe3

("image", Image),

[XAMPPRocky]

FWIW I think it would make sense to rename the Image type (not storage class) to #[spirv(image_type)] as the attribute, as that would keep the storage classes consistent.