Choose a view of the scene from the previous exercise that produces a view volume in which all objects are not fully contained. Apply the algorithm for polygon clipping that you developed in the previous exercise against the view volume. Write routines to display the scene using a parallel projection and a perspective projection. Use the OpenGL three-dimensional viewing functions to do this, choosing appropriate parameters to specify the viewing volume in each case. Allow the user to switch between the two projections via keyboard input and note the differences in the visual appearance of the scene in the two cases.