Hi Michael,

I guess we were typing at the same time.

Re:
> although it will have the shape of a line, it is going to be a
> closed curve that's all squashed down and running back over itself.

That's kind of what I was expecting and so didn't try it, but having actually tried it now that's not what I see happening. Like if I project the edge view of a circle onto a plane I get an open curve with endpoints at the right locations. It's not a nice simple line with only 2 control points, but it does have endpoints where I need them.

Re:
> I'll see about adding a method

Looking forward to it! Sounds cleaner for the parallel case too.

Re:
> Then to weed out the internal ones you could make a line and intersect
it with the curve, if there is an intersection other than at the tangent
point then you would skip it.

So draw a line through the point along the projection ray direction and verify that it only intersects the curve at that one point. I like it.

- Peer