The scale subroutine shrinks, expands, and mirrors objects. Negative values cause mirroring. All objects that are drawn after the scale subroutine executes are scaled. The scale subroutine creates a matrix and premultiplies it into the current matrix. The modeling subroutines are illustrated in the following figure .
Rotations are about the origin of the coordinate system.
The viewing transformations allow you to specify the position of the eye in the world coordinate system, and to specify the direction toward which it is looking. The polarview and lookat subroutines provide convenient ways to do this. The polarview subroutine assumes that the object you are viewing is near the origin. The specification is similar to polar coordinates, hence, the name. There is still one degree of freedom because these values tell only where the eye is relative to the object.