JarrettBillingsley / gl-rs

An OpenGL function pointer loader for Rust

gl-rs

An OpenGL function pointer loader for the Rust Programming Language.

Compilation

rustpkg build --opt-level=3 gl

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 an associated boolean value 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...
}

Generating the loader

The loader in gl.rs is 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 src/gen directory.

Todo

• Make the generator work properly GLX and WGL.