Question

The best example I can give is located at:

http://www.mathopenref.com/arclength.html

In that Java applet, imagine C is the object to be rotated around and A is the camera. I wish to move the camera to point B, but I do not know how to work out B’s co-ordinates. How do you do it? In my case, I know the positions of C and A, and the angle theta to rotate.

I know you can use:

• x = Xcentre + radius * sin(theta)
• y = Ycentre + radius * cos(theta)

but this fails to take into account the camera current position.

I can’t help but feel there’s some simple solution I’m missing.

Answer 1

Solved by using the equations listed and just reversing the calculation to derive theta. Then applied a check to ensure 360 degree rotations can be done (else only 180 degrees can).