test.rs

//do a bad polygon
    let gfrac = ((app.elapsed_frames() % 300) as f32)/300.0;
    let mut points = Vec::new();
    let s = 5;
    for k in 0..s {
        let frac = (k as f32)/(s as f32);
        let angle = frac*TAU;
        let r = (frac-0.5+gfrac).abs() * 300.0;
        points.push(pt2(r*angle.cos(), r*angle.sin()));
    }
    draw.polygon()
        .points(points)
        .rgba(1.0, 1.0, 1.0, 0.4);