[url]http://en.wikipedia.org/wiki/Torus[/url][br][br][math]x(\theta, \varphi) = a\,(R + r \cos(\theta)) \cos{\varphi}, \,\, y(\theta, \varphi) = b\,(R + r \cos (\theta)) \sin{\varphi},\,\, z(\theta, \varphi) = c\, r \sin \theta[br][/math][br][math]\theta \in [0, 2\pi],\,\,\, \varphi \in [0,2\pi] [/math][br][br]Clik on the [color=#0a971e]green points[/color] for randomize [math] r,R,a,b,c[/math] and colours.