I would have thought this would be trivial, but I still haven't found an easy method. All I want to do is draw a cone, a plane, and their intersection (which will be a conic section). Something similar to, for example:
or the picture here:
The same sort of standard pictures we've all seen a million times before.
I don't mind if I use a LaTeX drawing package, or something else, but I want to do it myself, so I can play around with the cone and plane to get the best possible diagram. I've tried a few online things such as 3dtin and shapesmith, but they're a bit flaky. It would be nice to use a vector drawing package and then export the result into LaTeX, but at this stage I'll settle for an image. It can also be a black and white wire diagram rather than a surface plot.
Has anybody created something like this before?