rs-gl_helpers

gl helpers

```rust extern crate gl; extern crate glutin; extern crate time; extern crate gl_helpers;

use glutin::GlContext; use gl::types::*;

use gl_helpers::*;

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

static 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 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(VERTEX, FRAGMENT);
program.get_uniform("alpha").set_1f(0.5_f32);

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

let mut playing = true;

let start_time = time::now();
let mut last_time = start_time;
let mut current_time;
let mut ms = 0f32;
let mut dt;

let mut size = [1f32; 2];

while playing {
    current_time = time::now();
    dt = (current_time - last_time).num_nanoseconds().unwrap() as f32 * 0.000001f32;
    ms += dt;
    last_time = current_time;

    events_loop.poll_events(|event| {
        match event {
            glutin::Event::WindowEvent { event: glutin::WindowEvent::Closed, .. } => {
                playing = false;
            },
            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();
}

} ```