wgsl-macro

A modular and async-capable preprocessor for WGSL (WebGPU Shading Language) shader source files.
Supports powerful directives like #import, #ifdef, #const, and conditionals to enable reusable, compile-time evaluated shader logic.

Use this crate to modularize your WGSL code, inject constants, and evaluate conditions in shaders before compilation.

✨ Features

• #import other shader modules by path or scheme (e.g. embedded://...)
• #const injection for compile-time constants
• #if, #ifdef, #ifndef, #else, #end logic blocks
• Nested and multi-branch conditional support
• Async import resolution (ideal for Web/WebGPU environments)
• Strong error handling and detailed diagnostics

📆 Installation

Add to your Cargo.toml:

wgsl-macro = "0.3.0"

🧪 Example

use wgsl_preprocessor::{ShaderProcessor, ShaderConstant, ShaderConstants};

let mut processor = ShaderProcessor::new();
processor.add_module("embedded://shaders/utils.wgsl", "fn util() {}");

let mut constants = ShaderConstants::new();
constants.set("LIGHT_COUNT", ShaderConstant::U32(50));

let source = r#"
    #import embedded://shaders/utils.wgsl
    const LIGHT_COUNT: u32 = 10;
    #if LIGHT_COUNT == 50
        fn main() {
            util();
        }
    #end
"#;

let result = processor.build(source, &constants).unwrap();
println!("{}", result);

🔧 Supported Directives

• #import path – Load another module by path
• #const NAME: TYPE = VALUE; – Define constants
• #if, #else if, #else, #end – Conditional logic
• #ifdef, #ifndef – Check if constants exist

🌐 Async Imports

You can collect all #import directives asynchronously using get_imports:

use wgsl_preprocessor::ShaderProcessor;

let imports = ShaderProcessor::get_imports(shader_src, |path| async move {
    // Fetch from disk, server, or embedded assets
    Ok(load_shader_from_source(path))
}).await?;

🚧 Roadmap

• Expression parser for more advanced constant evaluation
• GLSL support
• CLI tool for shader preprocessing

📄 License

Licensed under MIT or Apache-2.0 (your choice).

❤️ Contributions

PRs, issues, and suggestions are welcome! Whether you want to support #define-style macros, improve error reporting, or just fix typos — contributions are appreciated!