Crate wgsl_ln 

Experimental crate for writing wgsl in rust!

The wgsl! macro

The wgsl! macro converts normal rust tokens into a wgsl &'static str, similar to stringify!. This also validates the wgsl string using naga. Errors will be reported with the correct span.

pub static MANHATTAN_DISTANCE: &str = wgsl!(
    fn manhattan_distance(a: vec2<f32>, b: vec2<f32>) -> f32 {
        return abs(a.x - b.x) + abs(a.y - b.y);
    }
);

Most errors can be caught at compile time.

pub static MANHATTAN_DISTANCE: &str = wgsl!(
    fn manhattan_distance(a: vec2<f32>, b: vec2<f32>) -> f32 {
        // not allowed in wgsl
        abs(a.x - b.x) + abs(a.y - b.y)
    }
);

The #[wgsl_export(name)] macro

Export a wgsl item (function, struct, etc) via wgsl_export. Must have the same name as the exported item.

#[wgsl_export(manhattan_distance)]
pub static MANHATTAN_DISTANCE: &str = wgsl!(
    fn manhattan_distance(a: vec2<f32>, b: vec2<f32>) -> f32 {
        return abs(a.x - b.x) + abs(a.y - b.y);
    }
);

Using an exported item

pub static MANHATTAN_DISTANCE_TIMES_FIVE: &str = wgsl!(
    fn manhattan_distance_times_five(a: vec2<f32>, b: vec2<f32>) -> f32 {
        return #manhattan_distance(a, b) * 5.0;
    }
);

#manhattan_distance copies the manhattan_distance function into the module, making it usable. You can specify multiple instances of #manhattan_distance or omit the # in later usages.

• Note compile time checks still work.

pub static MANHATTAN_DISTANCE_TIMES_FIVE: &str = wgsl!(
    fn manhattan_distance_times_five(a: vec2<f32>, b: vec2<f32>) -> f32 {
        // missing comma
        return #manhattan_distance(a, b) * 5.0
    }
);

Ok what’s actually going on?

wgsl_export creates a macro_rules! macro that pastes itself into the wgsl! macro. The macro is #[doc(hidden)] and available in the crate root, i.e. crate::__wgsl_paste_manhattan_distance!.

You don’t need to import anything to use items defined in your crate, for other crates, you might want to blanket import the crate root.

mod my_shaders {
    pub use external_shader_defs::*;

    pub static MAGIC: &str = wgsl!(
        fn magic() -> f32 {
            return #magic_number();
        }
    )
}
pub use my_shaders::MAGIC;

naga_oil support

Enable the naga_oil feature for limited naga_oil support:

• Treat #preprocessor_macro_name as tokens instead of imports.
  • #define_import_path
  • #import
  • #if
  • #ifdef
  • #ifndef
  • #else
  • #endif

These values can no longer be imported.

• Checks will be disabled when naga_oil preprocessor macros are detected.

Macros

wgsl

Converts normal rust tokens into a wgsl &'static str, similar to stringify!. This also validates the wgsl string using naga. Errors will be reported with the correct span.

Attribute Macros

wgsl_export

Export a wgsl item (function, struct, etc).