Cameras
Since version V0.9.12, JMathAnim can manage several cameras. We will see how to use them to easily achieve some effects.
There are 2 predefined cameras built in JMathAnim, the default camera, that can be access through the public variable camera or the getCamera() method in your Scene2D class, and the fixed camera, accesible through getFixedCamera() method.
All MathObjects have a Camera object associated, that manages the conversion from math coordinates to screen coordinates. The math coordinates are the usual coordinates in the plane, that is, the origin at (0,0), y-coordinate increases upwards. Screen coordinates manage where the actual painting is done in the screen, movie frame, or image generated. They behave in a different way, for instance, the point (0,0) is always a the lower-left corner of the window, and y decreases upwards, but you don't have to worry about them. That's what Camera class is designed for. From now we will always refer to math coordinates.
The default camera object, as we have seen before, is centered at (0,0) with x ranging from -2 to 2. The y range is computed according to the aspect ratio of the screen. For example, if you are generating a 16:9 video, for example, y will range from -1.125 to 1.125. So what a Camera is essentially doing is mapping its math range into the screen or movie frame. A MathObject outside the camera range will be "outside the screen" and partially drawn or not drawn at all.
As we have seen, the Camera objects can be shifted and scaled (not rotated...yet)