rs-gl_helpers

gl helpers

```rust extern crate gl; extern crate glutin; extern crate mainloop; extern crate glhelpers;

use glutin::GlContext; use gl::types::; use gl_helpers::;

static SIMPLEVERTEXDATA: [GLfloat; 16] = [ // position uv 1f32, 1f32, 1f32, 1f32, -1f32, 1f32, 0f32, 1f32, 1f32, -1f32, 1f32, 0f32, -1f32, -1f32, 0f32, 0f32 ];

static SIMPLE_VERTEX: &'static str = " #version 120

uniform vec2 size;

attribute vec2 position;
attribute vec2 uv;

varying vec2 v_uv;

void main() {
    gl_Position = vec4(position * size * 0.5, 0, 1.0);
    v_uv = uv;
}

";

static SIMPLE_FRAGMENT: &'static str = " #version 120

uniform float alpha;

varying vec2 v_uv;

void main() {
    gl_FragColor = vec4(v_uv, 1.0, alpha);
}

";

fn main() { let mut screenwidth = 1024usize; let mut screenheight = 768usize;

let mut events_loop = glutin::EventsLoop::new();
let window = glutin::WindowBuilder::new()
    .with_title("Simple")
    .with_dimensions(screen_width as u32, screen_height as u32);
let gl_window = glutin::GlWindow::new(
    window,
    glutin::ContextBuilder::new()
        .with_vsync(true),
    &events_loop
).unwrap();

unsafe {
    gl_window.make_current().unwrap();
}

gl::load_with(|symbol| gl_window.get_proc_address(symbol) as *const _);

let gl_info = GLInfo::new();
println!("{}", gl_info.version());
println!(
    "OpenGL version: {:?}.{:?}, GLSL version {:?}.{:?}0",
    gl_info.major(), gl_info.minor(), gl_info.glsl_major(), gl_info.glsl_minor()
);

gl_set_defaults();

let program = GLProgram::new(SIMPLE_VERTEX, SIMPLE_FRAGMENT);

let buffer = GLBuffer::new(BufferTarget::Array, 4, Usage::StaticDraw, &SIMPLE_VERTEX_DATA);

let mut vertex_array = GLVertexArray::new();

vertex_array.bind();
vertex_array.add_attribute(&buffer, program.get_attribute("position"), 0);
vertex_array.add_attribute(&buffer, program.get_attribute("uv"), 2);

vertex_array.enable_attributes();

program.get_uniform("alpha").set_1f(0.5_f32);

let mut size = [1f32; 2];

main_loop::set(move |ms_f64| {
    let ms = ms_f64 as f32;

    events_loop.poll_events(|event| {
        match event {
            glutin::Event::WindowEvent { event: glutin::WindowEvent::Closed, .. } => {
                main_loop::stop();
            },
            glutin::Event::WindowEvent { event: glutin::WindowEvent::Resized(w, h), .. } => {
                screen_width = w as usize;
                screen_height = h as usize;

                gl_window.resize(w, h);
                gl_set_viewport(0, 0, screen_width, screen_height);
            },
            _ => (),
        }
    });

    gl_set_clear_color(&[0.3, 0.3, 0.3, 1.0]);
    gl_clear(true, true, true);

    size[0] = 1_f32 + ((ms * 0.005_f32).cos() * 0.5_f32);
    size[1] = 1_f32 + ((ms * 0.005_f32).sin() * 0.5_f32);
    program.get_uniform("size").set_2f(&size);

    gl_draw_arrays(DrawMode::TriangleStrip, 0, 4);

    gl_window.swap_buffers().unwrap();
});

main_loop::run();

} ```