Support vertex attrib parsing at crates/jsbindings/webgl

[yorkie]

Summary

We plan to use the Rust crate glsl-lang in crates/jsbindings/webgl.rs to parse vertex shader source code, extract all attribute metadata, and expose the results to C/C++ so they can be used for attrib location management (e.g., for getAttribLocation).

Implementation Steps

1. Use glsl-lang for GLSL parsing in Rust

   • Integrate glsl-lang as a dependency in the Rust workspace.
   • Implement a Rust struct (e.g., MyGLSLParser) that takes vertex shader source code and uses glsl-lang to parse and extract all attribute declarations, including name, type, and order.
   • Store the attributes in a struct with ordered locations (location assignment based on appearance).
   • Provide methods to query attrib metadata and location by name.

2. Expose the attribute info to C/C++

   • Use Rust's FFI (e.g., #[no_mangle] extern "C" functions) to expose functions for C/C++ to parse shader source and retrieve attribute info (names/types/locations).
   • Design C-compatible structs for the attribs and provide functions to allocate and free them from C/C++.
   • Document the FFI interface and expected usage from the C/C++ side.

3. Testing

   • Add tests for parsing and location assignment (covering various GLSL syntax cases).

Reference

• glsl-lang crate
• WebGL Spec: getAttribLocation
• C++ FFI in Rust

Related Code

• crates/jsbindings/webgl.rs (Rust binding and FFI interface)
• C++: WebGL shader/program management code

---

Please comment if you have suggestions about the FFI design or want to discuss specific integration details.