1) What is the .obj file format?

   M N
   x0 y0 z0
   . . .
   . . .
   . . .
   x(M-1) y(M-1) z(M-1)
   P0 Q0
   . . 
   . . 
   . . 
   P(N-1) Q(N-1)
  
Where

   M is an integer indicating the number of points in the object.
   N is an integer indicating the number of segments in the object.
   
   x0 y0 z0 through x(M-1) y(M-1) z(M-1) are floating point numbers
   listing the x, y, and z coordinates of each point.

   P0 Q0 through P(N-1) Q(N-1) list the indices of the points for each 
   segment.

Example:

        
       +---+
      /   /| 
     +___+ |
     |   | +
     |   |/
     +___+


     consider a simple cube with points (vertices):

     -1 -1 -1
     -1 -1  1
     -1  1 -1
     -1  1  1
      1 -1 -1
      1 -1  1
      1  1 -1
      1  1  1

     and segments (edges):
      
     -1 -1 -1    1 -1 -1
     -1 -1 -1   -1  1 -1
     -1 -1 -1   -1 -1  1
      1 -1  1    1 -1 -1 
      1 -1  1   -1 -1  1
      1 -1  1    1  1  1
     -1  1  1   -1 -1  1
     -1  1  1   -1  1 -1 
     -1  1  1    1  1  1
      1  1 -1    1 -1 -1 
      1  1 -1   -1  1 -1 
      1  1 -1    1  1  1 

The corresponding .obj file would be:

NOTE: This is a non-optimal object description, but is the output of the con
utility.

9 12
-1 -1 -1
-1 1 -1
-1 -1 1
-1 1 -1
-1 1 1
1 -1 -1
1 1 -1
1 -1 1
1 1 1
0 5
0 3
0 2
5 7
2 7
7 8
2 4
3 4
4 8
5 6
1 6
6 8

2) How did I generate my .obj files?

  The wireframe objects that I included with x3d were created with
  a raytracer that a friend of mine, Abe Megahed, is writing, and
  to which occasionally I do very evil programming hacks.  We are
  both undergraduates at the University of Wisconsin and members of the
  Undergraduate Projects Lab where we work on some of our projects.

  In the /pub/rendered_objs are a few examples of the images that some of the
  UPL'ers have made, again available via anonymous ftp at castlab.engr.wisc.edu
  (128.104.52.10).  They are all in miff format and require the
  ImageMagick image manipulation software which is found as
  /pub/ImageMagick.tar.Z  which is my favorite set of image utilities.

  Don't ask me to mail you these.  They are quite large.

  I really encourage you to at least try TOYS2_SS.miff out, particularly
  if you have a 24 bit display.

  A directory /pub/more_objs contains more .obj files to try out.