Drawing ellipses is easy. Just pick any canvas library: https://developer.mozilla.org/de/docs/Web/HTML/Canvas#Libraries https://developer.mozilla.org/de/docs/We

Drawing ellipses is easy. Just pick any canvas library: https://developer.mozilla.org/de/docs/Web/HTML/Canvas#Libraries https://developer.mozilla.org/de/docs/Web/HTML/Canvas#Librar... I'm afraid you have to calculate the intersections yourself though. I know there is a Processing(.org) plugin that does that kind of thing (might be called "intersection") and Processing can export to JS. I hope this helps at least a little bit.