glium 0.36.0

Elegant and safe OpenGL wrapper. Glium is an intermediate layer between OpenGL and your application. You still need to manually handle the graphics pipeline, but without having to use OpenGL's old and error-prone API. Its objectives: - Be safe to use. Many aspects of OpenGL that can trigger a crash if misused are automatically handled by glium. - Provide an API that enforces good pratices such as RAII or stateless function calls. - Be compatible with all OpenGL versions that support shaders, providing unified API when things diverge. - Avoid all OpenGL errors beforehand. - Produce optimized OpenGL function calls, and allow the user to easily use modern OpenGL techniques.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125

#[macro_use]
extern crate glium;
mod support;

use glium::index::PrimitiveType;
use glium::{Display, Surface};
use glutin::surface::WindowSurface;
use support::{ApplicationContext, State};

#[derive(Copy, Clone)]
struct Vertex {
    position: [f32; 2],
    color: [f32; 3],
}
implement_vertex!(Vertex, position, color);

struct Application {
    pub vertex_buffer: glium::VertexBuffer<Vertex>,
    pub index_buffer: glium::IndexBuffer<u16>,
    pub program: glium::Program,
}

impl ApplicationContext for Application {
    const WINDOW_TITLE:&'static str = "Glium screenshot example";

    fn new(display: &Display<WindowSurface>) -> Self {
        let vertex_buffer = {
            glium::VertexBuffer::new(
                display,
                &[
                    Vertex {
                        position: [-0.5, -0.5],
                        color: [0.0, 1.0, 0.0],
                    },
                    Vertex {
                        position: [0.0, 0.5],
                        color: [0.0, 0.0, 1.0],
                    },
                    Vertex {
                        position: [0.5, -0.5],
                        color: [1.0, 0.0, 0.0],
                    },
                ],
            )
            .unwrap()
        };

        // building the index buffer
        let index_buffer =
            glium::IndexBuffer::new(display, PrimitiveType::TrianglesList, &[0u16, 1, 2]).unwrap();

        // compiling shaders and linking them together
        let program = program!(display,
            100 => {
                vertex: "
                    #version 100

                    uniform lowp mat4 matrix;

                    attribute lowp vec2 position;
                    attribute lowp vec3 color;

                    varying lowp vec3 vColor;

                    void main() {
                        gl_Position = vec4(position, 0.0, 1.0) * matrix;
                        vColor = color;
                    }
                ",

                fragment: "
                    #version 100
                    varying lowp vec3 vColor;

                    void main() {
                        gl_FragColor = vec4(vColor, 1.0);
                    }
                ",
            },
        )
        .unwrap();

        Self {
            vertex_buffer,
            index_buffer,
            program,
        }
    }

    fn draw_frame(&mut self, display: &Display<WindowSurface>) {
        let mut frame = display.draw();
        // For this example a simple identity matrix suffices
        let uniforms = uniform! {
            matrix: [
                [1.0, 0.0, 0.0, 0.0],
                [0.0, 1.0, 0.0, 0.0],
                [0.0, 0.0, 1.0, 0.0],
                [0.0, 0.0, 0.0, 1.0f32]
            ]
        };

        // Now we can draw the triangle
        frame.clear_color(0.0, 0.0, 0.0, 0.0);
        frame
            .draw(
                &self.vertex_buffer,
                &self.index_buffer,
                &self.program,
                &uniforms,
                &Default::default(),
            )
            .unwrap();
        frame.finish().unwrap();

        // Now we can read the front buffer and save it
        let image: glium::texture::RawImage2d<'_, u8> = display.read_front_buffer().unwrap();
        let image = image::ImageBuffer::from_raw(image.width, image.height, image.data.into_owned()).unwrap();
        let image = image::DynamicImage::ImageRgba8(image).flipv();
        image.save("glium-example-screenshot.png").unwrap();
    }
}

fn main() {
    State::<Application>::run_once(true);
}