gl 0.4.0

OpenGL bindings

Usage

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

# #![allow(unused_imports)]
extern crate gl;
# fn main() {
// 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(|s| glfw.get_proc_address(s));

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

Calling a function that has not been loaded will result in a failure like: panic!("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.

# #![allow(path_statement)]
# extern crate gl;
# fn main() {
// accessing an enum
gl::TEXTURE_2D;

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

// functions that take pointers are unsafe
# let shader = 0;
# let c_str: *const i8 = std::ptr::null();
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...
}