Module quicksilver::tutorials::_11_mesh

A Mesh is a low-level graphics concept in Quicksilver consisting of a series of polygon vertices and a list of triangles.

This concept can be used to draw any shape: to make a rectangle, put the four vertices in the vertex list, and then create two triangles that together make up the rectangle.

Most user code need never encounter a mesh, but Mesh is extremely powerful. In fact, there is no special sauce available to Quicksilver's implementation of Drawable for Rectangle that a regular user of the library cannot access with a Mesh.

There are two ways to use Mesh: instantiate your own with Mesh::new or use Window::mesh to access the internal mesh of a window. To concatenate two meshes, use the Mesh::extend function.

To create a mesh that contains a triangle with a red vertex, a blue vertex, and a green vertex, you could write:

use quicksilver::graphics::{Background::Col, Color, GpuTriangle, Mesh, Vertex};
let vertices = vec![
    Vertex::new((400, 200), None, Col(Color::RED)),
    Vertex::new((200, 400), None, Col(Color::BLUE)),
    Vertex::new((600, 400), None, Col(Color::GREEN))
];
let triangles = vec![ GpuTriangle::new(0, [0, 1, 2], 0.0, Col(Color::WHITE)) ];
let mesh = Mesh { vertices, triangles };

To draw it you can then do:

window.mesh().extend(&mesh);

You have to do this every frame, because the window's mesh is cleared after it's drawn.

Drawing to a Mesh is important to defining your own Drawable objects. Drawable requires a single function definition, draw, with the signature

extern crate quicksilver;
fn draw<'a>(&self, mesh: &mut Mesh, background: Background<'a>, transform: Transform, z: impl Scalar)

We could create a Diamond struct that implements Drawable like so:

use quicksilver::{
    geom::{Rectangle, Shape, Scalar, Transform, Vector},
    graphics::{Background, Drawable, Mesh}
};

struct Diamond {
    center: Vector,
    radius: f32
}

impl Drawable for Diamond {
    fn draw<'a>(&self, mesh: &mut Mesh, background: Background<'a>, transform: Transform, z: impl Scalar) {
        let square = Rectangle::new_sized((self.radius, self.radius)).with_center(self.center);
        let rotation = Transform::rotate(45);
        square.draw(mesh, background, transform * rotation, z);
    }
}