Defines the viewer's position in polar coordinates. Azimuth defines the azimuthal angle in the x-y plane, measured from the y axis. Incidence specifies the angle of incidence in the y-z plane, measured from the z axis. The incidence angle is the angle of the viewport relative to the z axis. Twist defines the amount that the viewpoint is to be rotated around the line of sight using the right-hand rule.
Twist controls a rotation along the viewer's z axis.
Push the current transformation matrix onto the stack. Restore a previous transformation matrix. Scale the current transformation. Rotate the current transformation by the given angle about x, y, or z axis. The axis may be 'x' , 'y' , or 'z' .