Note: This excerpt does not include the lesson files. The lesson files are available with purchase of the book.
The project is an animation of a flame flickering at the top of a fictional company name. The shape of the flame constantly changes as well as the radial gradient fill inside of the flame. A linear gradient sweeps across the letters of the company name from left to right. In this lesson, you’ll animate both the flame and the colors that move across the letters.
In the previous two lessons, you learned to create animations with symbol instances. You could animate the motion, scale, rotation, color effect, or the filters applied to symbol instances. However, you couldn’t animate the actual contours of a graphic. For example, creating an animation of the undulating surface of the ocean, or the slithering motion of a snake’s body is difficult—if not impossible—with motion tweens. To do something more organic, you have to use shape tweening.
Shape tweening is a technique for interpolating the stroke and fill changes between different keyframes. Shape tweens make it possible to smoothly morph one shape into another. Any kind of animation that requires that the stroke or the fill of a shape to change—for example, animation of clouds, water, or fire—is a perfect candidate for shape tweening.
Because shape tweening applies only to shapes, you can’t use groups, symbol instances, or bitmap images.