Game Development Reference
Fig 2.34 The Inspector view of physics material.
2.6 Physics and the Principles of Animation
In their book The Illusion of Life , Disney animators Ollie Johnston and Frank
Thomas introduce 12 rules to be applied when creating animated films.
Squash and stretch:
The deformation of objects in reaction to the laws of physics;
for example, a tennis ball hitting a wall squashes on collision.
Presenting short actions or hints to a viewer of what is about to
happen; for example, a person about to jump in the air will bend their
Presenting an idea such that no mistake can be made as to what is
happening; for example, viewing an angry person's face gives a better
impression of their mood than the back of their head.
Straight-ahead action and pose to pose:
These are animation drawing methods. Straight-ahead action
refers to drawing out a scene frame by frame. Pose to pose refers
to drawing key frames or key moments in a scene and filling
in the gaps later.