# :goggles: shader-prepper

[![Crates.io](https://img.shields.io/crates/v/shader-prepper.svg)](https://crates.io/crates/shader-prepper)
[![Docs](https://docs.rs/shader-prepper/badge.svg)](https://docs.rs/shader-prepper)

**shader-prepper** is a shader include parser and crawler. It is mostly aimed at GLSL
which doesn't provide include directive support out of the box.

This crate does not implement a full C-like preprocessor, only `#include` scanning.
Other directives are instead copied into the expanded code, so they can be subsequently
handled by the shader compiler.

The API supports user-driven include file providers, which enable custom
virtual file systems, include paths, and allow build systems to track dependencies.

Source files are not concatenated together, but returned as a Vec of [`SourceChunk`].
If a single string is needed, a `join` over the source strings can be used.
Otherwise, the individual chunks can be passed to the graphics API, and source info
contained within `SourceChunk` can then remap the compiler's errors back to
the original code.

## Example

```rust
struct FileIncludeProvider;
impl shader_prepper::IncludeProvider for FileIncludeProvider {
    type IncludeContext = ();

    fn get_include(
        &mut self,
        path: &str,
        _context: &Self::IncludeContext,
    ) -> Result<(String, Self::IncludeContext), crate::BoxedIncludeProviderError> {
        Ok((std::fs::read_to_string(path)?, ()))
    }
}

// ...

let chunks = shader_prepper::process_file("myfile.glsl", &mut FileIncludeProvider, ());
```

License: MIT