If the world was just two points with a perfect arc this would be the end of the book, but alas or lucky for us, there are still many more complex shapes to learn and explore. There are many curves that are not perfectly aligned curves. Till now all the curves that we created were part of a perfect circle, but not any more. In this recipe, we will explore quadratic curves. The quadratic curves enable us to create curves that are not circular, by adding a third point—a controller to control the curve. You can easily understand this by looking at the following diagram:
A quadratic curve is a curve that has one control point. Consider the case when creating a line, we draw it between two points (A and B in this illustration). When we want to create a quadratic curve, we use an external gravity controller that defines the direction of the curve while the middle line (the dotted line) defines how far will the curve reach.