Conventions regarding positive and negative directions

Once we know the exact viewpoint of each object, we can make interactive method calls to change their viewpoints.

We can establish the desired viewpoints for setting the stage.

We will adopt the following conventions regarding positive and negative directions of motion:

• Move to the RIGHT is positive.
• Move to the LEFT is negative.
• Move UP is positive.
• Move DOWN is negative.
• Move FORWARD is positive.
• Move BACKWARD is negative.