Animation is more than the art of motion. The 3D games we play are full of motion, not all of it is animation. It is important to differentiate between the two. Motion is when an object moves or is moved. If an apple falls from a tree, it moved from the tree to the ground. This is an example of motion. Animation is when something moves on its own. The apple's descent to the ground did not occur because the apple was alive and decided to fall to its death; rather, the apple was forced to move either by gravity or other means.

When a player throws a hand grenade into a moving vehicle, the vehicle is likely to explode. The motion involved is the hand grenade's flight, and the vehicle's forward motion. The explosion will cause several particles of the vehicle, and people and things in it, to catapult in various directions. This is an example of physics creating motion. We will explore game physics in Chapter 6, Creating Gameplay. What about the player throwing the hand...