CS 381, Fall 2003
Assignment 9

General Information

• E-mail answers to the questions and C++ source for the program described below to me at ffggc@uaf.edu, using the subject "GA9". (If you wish to discuss the assignment with me via e-mail, use a different subject.)
  • If possible, please send your source as an attachment to your e-mail, rather than as part of the body text.
  • Send source only! No executables, project/workspace files, etc.
• Be sure to include your name in your e-mail.
• Due: Tuesday, November 25 (any time).
• Worth: 30 points.

Homework Policies

Questions (5 pts)

1. Lambert Cosine.
   1. What is the “Lambert cosine”? (Hint: Your answer had better have the word “cosine” in it.)
   2. What is the simplest way to compute the Lambert cosine?
   3. What is the primary use of the Lambert cosine in CG?
   4. What somewhat unrealistic assumption is behind the usual computation involving the Lambert cosine?
2. The Phong Model assumes that light sources are points. But mirror-like reflections of point light sources would not look realistic. How is this problem dealt with in the Phong model?

Program (25 pts)

• As before, draw a 3-D scene with proper HSR, use of the mode/view transformation, lighting, and non-text-window documentation.
• Make use of at least one of the more advanced lighting features in OpenGL:
  • Two-sided lighting.
  • Spotlights.

Suggestions for Full Credit

• Write and use a material class.

  One rather glaring defect (IMHO) in the OpenGL API is that materials are not dealt with as objects. Lights are. Display lists are. If you look into it, you will find that “textures” are. In GLUT, menus and windows are. But materials are handled as simply the current settings of a bunch of states.

  So fix this. Write a C++ class that encapsulates the idea of a material. So we can say this material should have these properties (remember to have reasonable defaults!) and now I want this to be the current material.

  By the way, I do not think this would be very difficult.

• Lots of other interesting things can be done with C++ classes. For example, do one of the following:
  • Write and use a “visible light source” class. It should handle both an OpenGL light and the visible version thereof. Various properties, including position, should be configurable by class users.
  • Write and use an improved interface for handling lighting details. (OpenGL lighting commands do seem to be a pain, don’t they? Write a better version.)
• Write a move-in-the-world interface (flying, etc.) with collision detection between the camera and at least one object in the scene.
• Do something with lighting that is more sophisticated than the Phong Model. (Of course, this means you cannot use OpenGL lighting. It also may mean that your program will be very slow, but that’s okay.)
• Do something with environment mapping (whatever that is ...).

Note