gl-rs

An OpenGL function pointer loader for the Rust Programming Language.

Usage

You can import the pointer style loader and type aliases like so:

extern mod gl;
// include the OpenGL type aliases
use gl::types::*;

You can load the function pointers into their respective function pointers using the load_with function. You must supply a loader function from your context library, This is how it would look using [glfw-rs] (https://github.com/bjz/glfw-rs):

// the supplied function must be of the type:
// `&fn(symbol: &str) -> Option<extern "C" fn()>`
gl::load_with(glfw::get_proc_address);

// loading a specific function pointer
gl::Viewport::load_with(glfw::get_proc_address);

Calling a function that has not been loaded will result in a failure like: fail!("gl::Viewport was not loaded"), which aviods a segfault. This feature does not cause any run time overhead because the failing functions are assigned only when load_with is called.

// accessing an enum
gl::RED_BITS;

// calling a function
gl::DrawArrays(gl::TRIANGLES, 0, 3);

// functions that take pointers are unsafe
unsafe {  gl::ShaderSource(shader, 1, &c_str, std::ptr::null()) };

Each function pointer has a boolean value associated with allowing you to check if a function has been loaded at run time. The function accesses a corresponding global boolean that is set when load_with is called, so there shouldn't be much overhead.

if gl::Viewport::is_loaded() {
    // do something...
}

Compilation

 % rustc --opt-level=3 ../gl.rs

Note that this will take a while to compile (~1m). This is because the loader big file (see the Todo section of this README for plans to reduce its size).

Generating the loader

The loader in gl.rs is actually generated using the [XML API Registry] (http://www.opengl.org/discussion_boards/showthread.php/181927-New-XML-based-API-Registry-released?p=1251775). If you would like to generate the loader yourself, please refer to the README in the generator directory.

Todo

• Provide cfgs so that the extensions can be limited. This should reduce the size of the compiled lib and the time it takes for the functions pointers to be loaded.
• Make the generator work properly with GLX and WGL.

Pull requests are welcome!