Project 2:
Scene Graphs, Transformations, and Navigation
CS 445: Computer Graphics, Fall 2006

Reading

• Chp 3: Implementing Modeling in OpenGL
• Chp 4: Mathematics for Modeling

Goals

• Practice building scene graphs.
• Understand the mathematics of transformations: points, vectors, matrices, homogeneous coordinates, dot and cross products.
• Navigating through a scene.

Part 1: Scene Graphs

• In class we saw how to create and implement the scene graph for a simple solar system and a robotic arm. In this part of the lab, you are to model an object of your choice. It should be built of multiple components and have a few moveable parts. This might be a simple humanoid with moving legs or a helicoptor that can move forward/backwards and has moving rotors. Once you decide on your object, do the following:
  • Draw a rough picture of the object, labeling the size and location of all components as well as all angles or directions where movement will take place.
  • Using your picture as a reference, draw a scene graph being careful to include all shapes and transformations.
  • Based on the scene graph, implement the object in OpenGL. User controls may be implemented either through buttons or key presses. It is important to keep your code clean. Use the robotic arm code as an example of how to organize your code. Include enough comments in your code so that someone reading it can understand what it is doing.

  The following are due Monday, Sept 25, in lecture:

  • Hand in your picture and your scene graph.
  • Demo your program to the class.
  • Zip together your code and email it to gorr. Include "CS445 Project 2, Part 1" in the subject line.

Part 2: Mathemetics

• In class, you will be handed a set of written problems. These will not be collected but we will go over them in class. Everyone will be asked to do and to explain several of the problems on the board. Grading will be based on your ability to do this.

• You may modify the Modelview Matrix in OpenGL by defining your own matrices and multiplying the Modelview Matrix by those matrices. Write a simple program that will do this. For example, experiment creating matrices for different types of transformations and see what they do to a teapot or other object. Have some fun with this. Try to come up with some real wacky results! Add some controls (buttons or keys) that let you modify the matrix interactively.

  The following are due Monday, Oct 2, in lecture:

  • Be prepared to present written problems on the board.
  • Demo code your program using matrices
  • Zip together your code and email it to gorr. Include "CS445 Project 2, Part 2" in the subject line.

Part 3: Navigation

• In class, we talked about how to create a system that enables the viewer to navigate through a scene. The viewer uses controls (e.g. key presses) for 6 possible actions: move forward/backward, turn right/left, look up/down. Create a scene (e.g. a large plane with various objects - cubes, teapots, etc). Implement the navigational system as described in class so that you may "fly around" your scene.

  The following are due Monday, Oct 9, in lecture:

  • Demo your program to the class.
  • Zip together your code and email it to gorr. Include "CS445 Project 2, Part 3" in the subject line.