Thanks for your reply

Let me further explain myself then!

So on the bottom screen I have a part of a circle, that I stretch to fit the width of the screen, thus changing the size of the circle.
Since it's not a complete circle, I can't determine where it's origin lies just by checking, and the radius is also not directly determinable..

I want to be able to rotate the object from outside of the screen onto the circle part (doesn't have to be an exact circular rotation, but the closer the better), to give the illusion that the circle itself is rotating.

Hope this helps

I did find this somewhere:



h = r - d
d = sqrt(4r2-c2)/2 = r cos(theta/2) = c cot(theta/2)/2

Would that serve to my purposes?