CS 365 at Valparaiso University

Spring, 2011

Michael Glass

Here is the syllabus.

CS 365 is a class in computer graphics, combining study of computer graphics algorithms, vocabulary, the use of the OpenGL package, and a taste of using a ray tracer.

On this web page you can find the topics we covered each week, plus miscellaneous notes, handouts, and assignments.

Textbook:	Edward Angel, Interactive Computer Graphics
	There will be additional handouts
Online Resources:	Here are the OpenGL, Mesa, and Py OpenGL web pages.
	Man pages for GL and GLU, which seem to have been copied from chapters 5 and 6 of the reference manual.
	The GLUT documentation is for window, mouse, and keyboard interaction.
	The NeHe Tutorials are recommended!
	A Gamma Correction test page is useful.
X Servers for MS Windows:	Several students recommend xming. Version 6.9 from May 2007 is free, pay for the newer version.
	Also recommend X-Win32, which has a free even older version and a more expensive pay newer version
	Finally note Cygwyn/X, free, up-to-date. When you run Cygwyn this is the X server, but apparently it is available as a separate download.
cslab machines:	Both C and Python OpenGL bindings are available on the cslab machines. (cslab.valpo.edu does not work, but cslab1 etc. do.)
	For compiling C programs, you can use the glcomp command. glcomp myprog (to compile myprog.c) ./myprog & (to run it)

Week of Jan 5, 7

The hacked-up example code is cubeo.c in C or cubeo.py in Python. Here is a C compile script: glcomp.

• Intro to the big idea: 3D model, synthetic camera.
• OpenGL model: draw objects as vertices, model view matrix transforms the points into model space as you draw them, projection matrix maps the view volume into a standard view volume.
• Standard axes, z is oriented away from the viewer into the picture.
• Standard view volume is a 2 x 2 x 2 cube centered at the origin.
• OpenGL example: spinning colored cubes, hacked up from Angel example A9.
• OpenGL drawing notions: glVertex, glBegin, glEnd
• OpenGL transformation notions: glRotate, glTranslate, glLoadIdentity, glMatrixMode
• Orthographic vs. perspective projection
• Graphics pipeline
• Color, glColor
• Surface normal vectors, glNormal
• Model consists of triangles, because three points define a plane segment and computations are considerably simplified.
• Idea of light sources and ambient light.

Week of Jan 10, 12, 14

Reading assignment: Chapter 1, Chapter 2 through 2.6 (Viewing). Quiz on Friday.
The example two cubes code with keyboard interaction and perspective is cubep.py in Python.

• X-Windows, what it is, "X server" remote operation
• Examples of keyboard interaction: glutKeyboardFunc
• Examples of perspective in OpenGL: gluLookAt, glFrustum
• Adding tick marks to the axes in the cubep example.
• Equations for drawing a sphere with quad strip.
• Perspective equation
• How to think of transformations as matrices

Week of Jan 19, 21

Reading assignment: Chapter 4.1 and 4.7 . Quiz on Friday Jan 28.
The example two cubes code with keyboard interaction and perspective has been updated to include axes with tick marks. It is available on the cslab machines in ~mglass/code/cubep.py

• Lab 1 assigned. (This is revision 2, handed out on Wednesday). There is an "assignment" on blackboard you can upload the files to.
• Here are the skeleton main programs: lab1skel.py and lab1skel.c
• More examples of thinking of transformations as matrices.
• What is Glut, what it does.
• Color: saturation.
• Beginning of discussion of lighting: basics of specular and diffuse reflection.

Week of Jan 24, 26, 28

Quiz on Friday Jan 28 on Chapter 4.1 and 4.7.

• More examples of thinking of transformations as matrices.
• Vector arithmetic. Cross products.
• Barycentric coordinates
• OpenGL material model: different specular, diffuse, ambient material reflectivities set using glMaterial
• OpenGL lighting model: different specular, diffuse, ambient lighting. Multiple light sources. Lights in or out of the model space.
• Lab 1 handed in.

Week of Jan 31, Feb 4

• Demonstration examples of illuminating the Lab 1 open sphere using differing diffuse and ambient light and material.
• Phong model imitating specular reflection.
• Mouse motion: computing a coordinate system based on the gaze of the synthetic camera.
• Demonstration of mouse motion using viewer's coordinates.

Week of Feb 7, 9, 11

Reading assignment: Chapter 4.3, 6.1-6.4. Quiz on Monday, Feb 14.

• The Phong model in more detail. Blinn half-angle approximation.
• Consequences of OpenGL lighting model: no reflections or refractions, point sources, sharp-edged shadows, problems due to interpolating across surfaces.
• Lab 2 assigned. (Updated to Rev. 3) Here is a screen shot
• INTERESTING PROBLEM FOR STUDENTS TO RESEARCH: Why do the spheres have that weird edge with the back-side color (as illustrated in the screen shot). Is there a way to fix this, and still retain the different colors on the front and back?

Week of Feb 14, 16, 18

Monday quiz on lighting equations, consequences of OpenGL lighting model, frames of reference.

• Much class discussion and demonstration related to Lab 2. Common issues: vector operations, normals, getting specular lighting to work.
• Beginning discussion of Bressenham's algorithm, drawing lines using integer arithmetic.
• Lab 3 handout, with in-class demos. Considering difficulties students had with lab 2, this program will be written as two parts, handed in as labs 3 and 4.
• Data files for labs 3 and 4: honolulu.txt (Honolulu), nmtopo.txt (New Mexico), objects.txt (Assorted objects).
• Code file for labs 3 and 4: read_heights.c C subroutine for reading dynamically-allocated 2-D array, also read_heights.py in Python.

Week of Apr 11, 13, 15

Reading for next Monday's quiz: Chapter 13 Advanced Rendering.

• Lab 5, elementary operations: writeup trianglelab.pdf and code triangleskel.c.
• Introduction to ray tracing
• Introduction to Povray

Last update: 20 Feb 2011
Michael Glass