Rust glium ( OpenGL ) triangle and square

rust の glium ライブラリを利用して、三角と四角を同一ウィンドウに
表示します。

実行結果

プログラム

#[macro_use]
extern crate glium;

fn main() {
    use glium::{DisplayBuild, Surface};
    let display = glium::glutin::WindowBuilder::new()
        .with_dimensions(800, 600)
        .with_title(format!("Glium Triangle and Square"))
        .build_glium().unwrap();

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

    implement_vertex!(Vertex, position);

    // triangle
    let vertex1 = Vertex { position: [-0.75, -0.5] };
    let vertex2 = Vertex { position: [-0.5 ,  0.5] };
    let vertex3 = Vertex { position: [-0.25, -0.5] };
    let shape1 = vec![vertex1, vertex2, vertex3];

    let vertex_buffer1 = glium::VertexBuffer::new(&display, &shape1).unwrap();
    let indices1 = glium::index::NoIndices(glium::index::PrimitiveType::TrianglesList);

    //square
    let vertex1 = Vertex { position: [ 0.25, -0.5] };
    let vertex2 = Vertex { position: [ 0.25,  0.5] };
    let vertex3 = Vertex { position: [ 0.75,  0.5] };
    let vertex4 = Vertex { position: [ 0.75, -0.5] };
    let shape2 = vec![vertex1, vertex2, vertex3, vertex4];

    let vertex_buffer2 = glium::VertexBuffer::new(&display, &shape2).unwrap();
    let indices2 = glium::IndexBuffer::new(&display,
                   glium::index::PrimitiveType::TrianglesList,
		   &[0u16, 1, 2, 2, 0, 3,]).unwrap();

    let vertex_shader_src = r#"
        #version 140

        in vec2 position;

        void main() {
            gl_Position = vec4(position, 0.0, 1.0);
	}
    "#;

    let fragment_shader_src = r#"
        #version 140

        out vec4 color;

        void main() {
            color = vec4(1.0, 0.0, 0.0, 1.0);
        }
    "#;

    let program = glium::Program::from_source(&display, vertex_shader_src,
		  fragment_shader_src, None).unwrap();

    loop {
        let mut target = display.draw();
	target.clear_color(0.0, 0.0, 1.0, 1.0);
	// triangle
	target.draw(&vertex_buffer1, &indices1, &program,
                    &glium::uniforms::EmptyUniforms, &Default::default()).unwrap();
        // square
        target.draw(&vertex_buffer2, &indices2, &program,
                    &glium::uniforms::EmptyUniforms, &Default::default()).unwrap();
	target.finish().unwrap();

	for ev in display.poll_events() {
	    match ev {
	        glium::glutin::Event::Closed => return,
		_ => ()
            }
        }
    }
}

Cargo.toml

[package]
name = "triangle"
version = "0.1.0"
authors = ["xxxxx"]

[dependencies]
glium = "*"

vertex, VertexBuffer, IndexBufferの設定
三角形と四角形のvertex, VertexBuffer, IndexBufferをそれぞれ準備します。
IndexBufferの設定では、三角形では頂点indexを使用しないのでNoIndicesを
使います。
四角形では頂点indexを使用しているので、IndexBufferを使います。

描画
target.draw()文を2回使って、三角形と四角形を描画します。