STATIC SUB Perspective ( Fovy AS Float, Aspect AS Float, ZNear AS Float, ZFar AS Float )
Glu.Perspective specifies a viewing frustum into the world coordinate system. In general, the aspect ratio in Glu.Perspective should match the aspect ratio of the associated viewport. For example, Aspect = 2.0 means the viewer's angle of view is twice as wide in x as it is in y. If the viewport is twice as wide as it is tall, it displays the image without distortion.
The matrix generated by Glu.Perspective is multipled by the current matrix, just as if Gl.MultMatrix were called with the generated matrix. To load the perspective matrix onto the current matrix stack instead, precede the call to Glu.Perspective with a call to Gl.LoadIdentity.