OpenGL is a cross-platform graphics API that is widely used for rendering 2D and 3D graphics.
To use OpenGL in Rust, you can use the glium library, which is a safe wrapper around OpenGL. Here is an example of how you could use the glium library to draw a 3D triangle:
extern crate glium;
use glium::{glutin, Surface};
fn main() {
let event_loop = glutin::event_loop::EventLoop::new();
let window = glutin::window::WindowBuilder::new()
.with_title("Hello world")
.with_inner_size(glutin::dpi::LogicalSize::new(1024, 768));
let context = glutin::ContextBuilder::new();
let display = glium::Display::new(window, context, &event_loop).unwrap();
#[derive(Copy, Clone)]
struct Vertex {
position: [f32; 3],
}
implement_vertex!(Vertex, position);
let vertex1 = Vertex { position: [-0.5, -0.5, 0.0] };
let vertex2 = Vertex { position: [0.0, 0.5, 0.0] };
let vertex3 = Vertex { position: [0.5, -0.25, 0.0] };
let shape = vec![vertex1, vertex2, vertex3];
let vertex_buffer = glium::VertexBuffer::new(&display, &shape).unwrap();
let indices = glium::index::NoIndices(glium::index::PrimitiveType::TrianglesList);
let vertex_shader_src = r#"
#version 140
in vec3 position;
void main() {
gl_Position = vec4(position, 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();
let mut closed = false;
while !closed {
let mut target = display.draw();
target.clear_color(0.0, 0.0, 1.0, 1.0);
target
.draw(&vertex_buffer, &indices, &program, &glium::uniforms::
hat is the complete example of how to draw a 3D triangle using the glium library and OpenGL.
In this example, the program creates a window using glutin and sets up a glium::Display to render to the window. It then defines a Vertex struct to represent a 3D vertex and creates a VertexBuffer containing a triangle made up of three vertices.
Next, the program defines vertex and fragment shaders using the GLSL shading language and creates a glium::Program from the shaders. The vertex shader transforms the 3D vertex positions into clip space, and the fragment shader sets the color of each fragment to red.
Finally, the program enters a loop and uses the draw method of the glium::Surface to draw the triangle to the window. The draw method takes the vertex buffer, index buffer, program, and uniforms as arguments, and renders the triangle using the specified graphics pipeline.
Here is an example of how you could rotate the triangle using OpenGL and the glium library:
let mut angle = 0.0;
while !closed {
let mut target = display.draw();
target.clear_color(0.0, 0.0, 1.0, 1.0);
let model = [[angle.cos(), angle.sin(), 0.0, 0.0],
[-angle.sin(), angle.cos(), 0.0, 0.0],
[0.0, 0.0, 1.0, 0.0],
[0.0, 0.0, 0.0, 1.0f32]];
let uniforms = uniform! { model: model };
target
.draw(&vertex_buffer, &indices, &program, &uniforms, &Default::default())
.unwrap();
target.finish().unwrap();
angle += 0.01;
event_loop.poll_events(|event| {
if let glutin::event::Event::WindowEvent { event, .. } = event {
match event {
glutin::event::WindowEvent::CloseRequested => closed = true,
_ => (),
}
}
});
}In this example, the program introduces a new uniform called model that represents the model transformation matrix. The model transformation matrix is used to rotate the triangle around the z-axis by a small amount each frame.
The program then passes the model uniform to the draw method as part of a glium::uniforms::Uniforms struct, along with the vertex buffer, index buffer, program, and default draw parameters. The draw method uses the specified graphics pipeline to render the triangle to the window, applying the model transformation to rotate the triangle.
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