Is the parking meter properly oriented?
Although you can’t tell anything about the orientation of the parking meter in Figure 6, I made the ice skater temporarily invisible so that I could see the parking meter by itself. The widest dimension of the head on the parking meter lines up with the red axis, which strongly suggests that it is aligned with the ground and the world. Ice skater and parking meter have had a collision As you can see in Figure 6, there is nothing to prevent two objects from occupying exactly the same space in Alice (and in most other 3D environments as well). This may be another good reason why an animation program would need to keep track of the viewpoints of all its objects; to avoid collisions between objects. Some conventions regarding positive and negative directions Now that we know exactly where the two objects are located, we are prepared to interactively call methods on the objects to change their viewpoints to the desired viewpoints for setting the stage. Before doing that, however, we need to
