I'm working on rotating human limbs in a 3d game. I use Linear Algebra matrix rotations and translations to achieve moving the human and limbs. I currently can rotate around a pivot point by first translating to the pivot point then performing the rotation and finally translating back to the origin. I do that easily enough for the shoulder. However I cannot figure out how to also add in a rotation around the elbow for the forearm. The whole issue of the upper arm rotating thus moving the elbow point which I must then rotate around is throwing me off.
I've tried the following for the forearm rotation around the elbow:
1)translate to shoulder, rotate, translate to origin, translate to forearm, rotate, translate to origin 2)translate to shoulder, rotate, translate to forearm, rotate, translate to shoulder, translate to origin
Neither work for me. Any suggestions? I'm really stuck on this one.