I have a 3D object.
I would like to perform a 3D rotation about its COM (centre of mass), in terms of theta and phi. Not about the axes. I did have a piece of code to do this, but have lost the official reference for where I saw this worked out in more detail. I know it was a coupled combination of a rotation by theta and then phi for example.
Can anyone point me to a good source of information on this.