Apple Shake 4 - Manual (Page 779)

Chapter 26 Transformations, Motion Blur, and AutoAlign 779
In the following example, two elements are composited together to simulate a car
moving forward with spinning wheels: an image of a car body and a single graphic
representing the wheel graphic. The wheel graphic is used twice, once for the back
wheel and once for the front wheel. The colored dots on the wheels will illustrate the
improper and proper arrangements of nodes necessary to produce realistic motion blur
for this simulation.
In the following node tree, a Move2D node (renamed SpinWheel) is animated to rotate
the wheel. The PositionFrontWheel node is a non-animated Move2D that pans a copy of
SpinWheel to the front wheel position. The two wheel nodes are composited together
(RearWheelOverFront), and the result is composited over the car body (WheelsOverCar).
To animate the car forward, a Move2D node (MoveCar1) is applied, which pans the
entire image to the right.