How do I determine the position of one vector relative to another?

Question

I'm making a game for Kinect in Unity which tracks hand movements. I have the player's root position and the position of their fist stored as 3-dimensional vectors (Vector3 in Unity), but they're both in world space.

How can I determine the location of the player's fist relative to their root position?

Answer 1

Use Vector3 relativeFistPosition = globalFistPosition - globalRootPosition; to get the fist position relative to the root. Use this new Vector3 for comparing different moves.