CS 445/645: Introduction to Computer Graphics

Goal: Model, paint, and render a 3-D character using Teddy, Chameleon, and OpenGL

URL: http://www.cs.virginia.edu/~gfx/Courses/2000/intro.fall01/Exercises/assignment4-1.htm

Assigned: Tuesday, October 30th, 2001

Due: Wednesday, November 7th, 2001 at Midnight

Relevant reading/files/software:

• We continue to use OpenGL (http://www.opengl.org). The OpenGL Red Book is available here:
    http://fly.cc.fer.hr/~unreal/theredbook/
• Teddy: http://www.mtl.t.u-tokyo.ac.jp/~takeo/teddy/teddy.htm
• Chameleon: (http://www.mtl.t.u-tokyo.ac.jp/~takeo/chameleon/chameleon.htm)

Synopsis: The goal of this two part assignment is to generate three-dimensional models with interesting color and texturing. For this first part, you will use a program called Teddy to create a three-dimensional model. Teddy allows you to save the model in OBJ format. You must then use Chameleon to load the OBJ model you created with Teddy and you must paint it.  Finally, you will adapt the starter OpenGL code from assignments 2 and 3 to load the OBJ and  BMP files generated by Chameleon and to display the textured model in a window. An additional 10% in points will be awarded to whomever creates (more than one person in case of ties) the best model/texture.

Specifics: This really isn't supposed to be a hard assignment.  Using Teddy and Chameleon should be easy, though you may encounter bugs with both programs.  Just work around them and build your OBJ and BMP files.  A former UVa CS undergrad named Dennis Cosgrove helped write Chameleon.  Teddy is a great program that was recognized as one of the two best papers at Siggraph 1999.  Teddy is great because of the intuitive interface it provides for creating 3D models.  When you think about the complicated 3-D operations your are performing via a 2-D window, it's pretty impressive.  I recommend reading their Siggraph paper, which can be found on the Teddy web page.  Make sure the Teddy model you build demonstrates the use of Extrusion and Bend.

The coding portion of this assignment should be easy as well.  I suggest starting with the code from Assignment 3 and add texture map functionality by following the example in Assignment 2.  Your program must accept two command line arguments, the first is the name of the .obj file and the second is the name of the .bmp file.  Your program need not do anything with clipping planes; you can throw that part of the code away.  Your program must allow the user to rotate the model and zoom into the model.  You may change the lighting if you wish.

OBJ Files:

• The OBJ file format looks nearly identical to the .poly format from assignment #3. To see for yourself what the objs look like, run Teddy and generate a couple models. Notice that Teddy throws in some extra stuff at the bottom of the .obj file.  You can either delete that stuff or build a file loader that ignores it.  
• Chameleon generates some extra information that does matter, the texture coordinates, vt.  Your loader must correctly keep track of the texture vertices and you can decide if you want to use the vertex normals, vn, from the .obj file or create your own.  
• The OBJ file doesn't include the first two lines: vertices: ###, faces: ###.  You can add these manually or change your file loader to be dynamic.  (To learn the number of vertices (or faces) in a .obj file, use UNIX and perform the following: cat file.obj | grep "v " | wc -l) 
• You're also going to care about the number of texture vertices, so add an extra line to the top of your .obj file if you wish to know this number ahead of time (for example, textureCoords: ###).  I don't know why Chameleon generates more texture vertices than there are vertices, but this assignment should work nonetheless.  
• You'll notice that the .obj file that Chameleon outputs has some extra information stored with each face: #1/#2/#3 #4/#5/#6 #7/#8/#9.  Similar to the poly files, this corresponds to the indices of three vertices (#'s 1, 4, and 7), their texture coords (#'s 2, 5, and 8) and their normals (#'s 3, 6, and 9).

• 15 pts - Create interesting model using Teddy and Chameleon. Model should include extrudes and bends. The cooler, the better.
• 15 pts - OBJ file parser. Must be able to scan through the .obj file and retrieve the vertex, texture, and face data.
• 20 pts - GL viewer. Must be able to generate GL polygons that represent the obj model.
• Extra credit for the best model (I'll provide multiple credits if there are ties)

Collaboration/Web Resources:  You may use the web to help you with this assignment.  As per the earlier assignments, you can talk to your classmates about your work, but you cannot look at each other's code or work side-by-side to generate your code.

Turning in the assignment:

• I have had Small Hall SGI accounts created for everyone in the class.  Use the same login/password as you use for Blue.unix.
• Verify that your code compiles and runs correctly on one of the SGI machines in Small Hall (sgi-1.unixlab.virginia.edu for example). We will use these machines for compiling all assignments.
• Write a README file with your login, your name, what you did, and anything you'd like us to notice or know about your demo.
• Deposit the README and all files required to compile and run you code in the following directory:
       /courses/cs/445_brogan/Students/<username>/Exercise4-1