With the techniques from the last two chapters and a little creativity, you can render any 2D or 3D figure you can think of. Whole objects, characters, and worlds can be built from line segments and polygons defined by vectors. But, there’s still one thing standing in between you and your first feature-length, computer-animated film or life-like action video game−you need to be able to draw objects that change over time.
Animation works the same way for computer graphics as it does for film: you render static images and then display dozens of them every second. When we see that many snapshots of a moving object, it looks like the image is continuously changing. In chapters 2 and 3, we looked at a few mathematical operations that take in existing vectors and transform them geometrically to output new ones. By chaining together sequences of small transformations, we can create the illusion of continuous motion.