How can I draw an object in openGL that always faces the camera? [duplicate]

Question

Possible Duplicate:
Inverting rotation in 3D, to make an object always face the camera?

I have some 2D images in 3D space that I would like to face the camera at all times. These objects are inside a stack of transformations (since I want them to move relative to another object, to keep a long story short). What would be the easiest way to implement this?

Answer 1

I answered this already here: Inverting rotation in 3D, to make an object always face the camera?