Hi Peer,

re:
> 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.

For the case of a circle it happens to have control points directly on the curve at the quadrants.

In a more general case like this it won't have any points like that:




The squashed curve has degenerate first derivatives with zero magnitude at the folding spots which tends to throw a monkey wrench into various numeric analysis stepping mechanisms.

It would probably be good to handle this case better in the project command by finding these spots before the projection and splitting it up at those points.


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

Yup, it's like a ray fire visiblity test.

- MIchael