Revision as of 02:50, 20 October 2013

Project 4: Light and Shade

This project is on OpenGL lighting and shading, and includes GLSL shader programs.

This project is due on Friday, November 1st at 1:30pm. It will be discussed in Center Hall 105 on Monday, October 28th at 3:00pm.

Note that GLSL shaders, which are needed for part 2 of the assignment, will be covered in class on Tuesday, October 22nd.

1. Mouse Control (20 Points)

Start by reviving your application from assignment 2: you will need to be able to display the cube, as well as the following three 3D models into your application and display them at reasonable sizes (screen filling). The function keys should switch between the models.

These are the models you need to be able to load, you will have to unzip them to get at the OBJ files. Note that some of them are different files than before, as we now need files with normals. The OBJ reader we gave you in project 2 already parses normals.

• Dragon (same as before)
• Bunny (new)
• Head (new)

You are welcome but not required to support the keyboard commands from assignment 2 to move around the models. However, you will need to add mouse control, which will allow rotating the model about the center of your OpenGL window, as well as scaling the model up and down. The left mouse button should be used for rotation, the right mouse button should zoom in and out when the mouse is moved up or down while it is pressed.

This video shows how the trackball-like rotation should work. We provide sample code for the trackball rotation. You will need to adapt it to the syntax of your matrix and vector classes and get it to work within your application.

To access the mouse x and y coordinates, you will need to use GLUT's callback functions glutMouseFunc(), which gets called when you press a mouse button, and glutMotionFunc(), which gets called constantly while you hold the button down and move the mouse. Note that successive trackball rotations must build on previous ones; at no point should the model snap back to a previous or default position.

2. OpenGL Lighting and Shading (30 points)

Write classes to manage light and material properties (Light and Material). As a starting point, refer to the relevant sections in Chapter 5 of the OpenGL Programming Guide, as well as the OpenGL Lighting FAQ.

Associate material properties with each of the four 3D model files: two of them should be shiny, and the other two should be shiny and diffuse - you choose which. Use colors other than white. (10 points)

Create three light sources: one directional light, one point light and one spot light. The spot light should always point towards the center of the OpenGL window. Give them initial positions and colors. Each of them must have a different position and color. The spot light should have a spot width narrow enough so that it only illuminates a small part of the surface of the models. Toggle each of them on and off with one of the number keys: 1, 2, and 3. Rotate those light sources which are on with the 3D model.

Add a freeze mode for the 3D model and toggle it with the 'm' key: when it is enabled, the model will not respond to mouse control commands and instead stay in its last orientation and size. In this mode only the enabled light sources rotate and zoom in and out.

Notes:

• OpenGL multiplies light position and direction with the Modelview matrix when they are set. Therefore, you need to modify the Modelview matrix with your mouse control routines to rotate the light sources, independently for each light source.
• To ascertain that the normals of your 3D models will survive zoom operations correctly, you should use the following OpenGL command: glEnable(GL_NORMALIZE).
• By default, OpenGL uses a simplified model for the calculation of the highlights. For a more realistic model add this command to your code: glLightModelf(GL_LIGHT_MODEL_LOCAL_VIEWER, GL_TRUE).

2. GLSL Shader Programs (50 Points)

Under construction.

3. Extra Credit (10 Points)

Under construction.