How to Move An Entity Along Arc Path
This article posted a few years ago may be of help:
http://drive-cad-with-code.blogspot.ca/2012/03/moving-entity-along-curve.html
While it is wriiten in ObjectARX .NET API, not C++, you get the idea and can see it is fairly easy to do.
OK, that would be mote a math/geometry problem than a AutoCAD technics (Jig) problem.
For example, you may want the moving entity rotates while moving, similar like the Moom moves around the Earth: while moving, it also rotates so that it alway with one side facing the Earth.
Assume you have an arc, which is a quarter of cricle. When move the antity from the arc's start to the end, the entity would also need to rotate 90 degree. Therefore, you can use the silimalr technics shown in my article and then get rotate angle (90 degree when moved a quarter of circle). It would be easy to calculate what the roate angle of the entity should be while moving long a circle (or arc). Once you get the rotation angle figured out, you just apply a rotation transform to the moving entity in the Jig's sampling code.
The calculating should be fairly easy. Is this video clip shows what the effect you are after?
If yes, then what I did is just a minor update to the code posted in my old article. I can update that article to show to minor code change. Of course, it is .NET API code. But you can get the idea on how to rotate the moving object while dragging it along an arc/circle, and do the similar thing in your C++ jig.
OK, the article is updated.
As you can see the code to calculation the rotation angle in method GetRotationAngle() is really simple. Since you do C++ Jig, the code would be somewhat different, but the logic is the same.
HTH
