// see https://en.wikipedia.org/wiki/Torus_knot
void TorusKnot(GeometricObject obj)
{
System.Func <float, Vector3> f = (phi) => {
var o = new Vector3();
var p = 3f;
var q = 8f;
var r = Mathf.Cos(q * phi) + 2f;
o.x = r * Mathf.Sin(p * phi);
o.y = r * Mathf.Cos(p * phi);
o.z = -Mathf.Sin(q * phi);
return(o);
};
var alpha = 1.0f;
var n = 1200;
var frontColors = new List <Color32> ();
var points = new List <Vector3> ();
frontColors.Clear();
for (var i = 0; i < n; ++i)
{
var hue = (float)i / n;
var cl = Color.HSVToRGB(hue, 1f, 1f);
cl.a = alpha;
frontColors.Add(cl);
}
points.Clear();
for (var i = 0; i < n; ++i)
{
var w = 2f * Mathf.PI * (float)i / n;
points.Add(f(w));
}
obj.Begin();
obj.SetLineRadius(0.3f);
obj.SetLineTopology(Pen.Topology.Close);
obj.AddLine(points, frontColors);
obj.End();
}