CSCE 4230  Program #3


        Due date:  Thursday, March 5, 2009


        Write an interactive OpenGL program that displays a small solar
        system by modifying planet.c (OpenGL Programming Guide, p. 154)
        as follows.

          1)  Add a second planet with radius .5 at distance 5 units from
              the center of the sun.  Replace global angle year by a pair
              of angles, year1 and year2, and increase or decrease both
              (by different but reasonable amounts) when the user enters
              'y' or 'Y', respectively.  Also, replace day by day1 and day2,
              and alter both (not necessarily by the same amount) in response
              to keypress 'd' or 'D'.

          2)  Add a moon with radius .1 orbiting the second planet at
              distance 1.5 from its center.  Whenever the year angle is
              altered, update angle month by an amount chosen to produce
              10 months per year.

          3)  Use function glFrustum in place of gluPerspective to define
              a view volume with center (0,0,2*r) and radius r, where r
              is large enough to contain the entire system.

          4)  Allow the user to zoom in and zoom out with the PageUp and
              PageDown keys and/or 'Z' and 'z'.  Zooming is achieved by 
              simply altering the first four parameters in the call to 
              glFrustum.

          5)  Add a menu (right mouse button) with all user control options
              (including exit on the Escape key) listed.



        Email the source code with file name prog4.c or prog4.cpp to
        Ismail Mohammed:  im0058@unt.edu.

        Also submit a source code listing at the beginning of class on 
        the due date.