Homework 5

22C:151 Introduction to Computer Graphics

Due Tuesday, October 14, 2003

15 points

This assignment involves a few small extensions of Homework 3, to get ready for use in developing your ray tracing program in Homework 6.

In Homework 5 you will implement a recursive ray tracer. Instead of requiring users to edit, by hand, a text file to describe the scene to be rendered, we'd like to be able to let users create their scenes interactively using a program like that of Homework 3. Using your Homework 3 program, users can create and position objects and the viewpoint, enabling them to quickly set up a nice scence. The idea here is to add functionality to Homework 3 that will enable you to use save and then use that scene description as input for your ray tracer.

Note that your ray tracer will only be required to handle spheres and boxes (cubes scaled by possible differents amounts along each axis). So, you only need to update/handle Homework 3 features relevant to spheres and boxes (not cones, cylinders, etc.)

Requirements:

• add the ability to specify different material properties for each object. This is easy, though perhaps a little tedious using GLUT. You may ignore ambient and emissive properties - we won't use them in the ray tracer.
• add the ability to specify a transparency and a refraction coefficient for each object.
• add the ability to create, position, and specify the diffuse and specular color properties of lights
• add the ability to specify global ambient light color and global attenuation properties (see the file format below to know what kind of values are needed)
• add the ability to save a description of the current scene in a text file. The idea is that after you create some objects and move them and the camera around, you use a menu selection or keyboard key to trigger the creation of a text file containing the description of the current scene. The format is described in file-format.text.
• add the use of simple OpenGL transparency to your program. This is not especially important. You would still be able to do a successful ray tracer without this capability, but it's a fairly simple and useful thing to learn (and will nicely demonstrate some differences between simple OpenGL transparency and what you'll get via ray tracing transparency). Although it only requires a few lines to do this, it can be tricky to get it working usefully. If you can't figure out how to do it, ask Jim or Ting (but only after everything else works!).

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Submitting your program