CS 248: Introduction to Computer Graphics

Pat Hanrahan

Assignment 2 Announcements

• Announcement 4 - 2/19/96 6:25 PM
  
• Announcement 3 - 2/18/96 9:15 PM
  
• Announcement 2 - 2/18/96 7:45 PM
  
• Announcement 1 - 2/16/96 2:30 AM

Announcement 4 - 2/19/96 6:25 PM

From Homan Igehy.

The grading criteria for RasterizeXor() has been refined slightly. The new grading criteria is:

5	A triangle shows up on the screen.
5	The triangle does xor'ing of the pixels.
5	The triangle is clipped correctly.
5	You rasterize only pixels within the triangle.
5	You mesh triangles correctly.
5	Performance.
30

5 points were taken away from the first criteria to create the third criteria.

Announcement 3 - 2/18/96 9:15 PM

From Homan Igehy.

Thanks to Denton Gentry for these.

Portability issues:

• gettimeofday() may take two parameters on different architectures, rather than one argument as on the SGI's. See the man pages for help with these.
• Single-precision math operations are not part of ANSI C yet, and are not necessarily in <math.h>. In particular, if you are on a Sun platform, include <sunmath.h> and link with -lsunmath.
• On non-SGI systems without sginap(), use usleep(), nanosleep(), or sleep().
• cube.c was changed. If CreateCube() has a NULL arg for the second argument, it used to seg fault on some systems. This has been fixed.

Announcement 2 - 2/18/96 7:45 PM

From Homan Igehy.

There was a small bug inside:

/usr/class/cs248/assignments/assignment2/template/main.c .

when you had both -rasfile and -autorefine. This is fixed.

Announcement 1 - 2/16/96 2:30 AM

From Homan Igehy.

If you have not yet begun work on Assignment 2 as of the time above, you can skip this announcement.

If you have followed the directions in README.starting, and have set up the files in your Assingment 2 working directory, you should note that there has been a change in the way things are being done.

Instead of holding your own copies of the files we provide, you should instead link to the files kept in the class directory. This will allow us to fix bugs and add features in a manner that will keep you from having to recopy these files every time we make a change.

If you don't care about the motivation behind this change, skip this next section:

The motivation behind this is as follows: today at 11:00 AM, your friendly TA Andrew Beers (who is doing the work for Assignment 2 just like you are in order to debug the process I created) noticed that the vertices weren't being fed into the rasterize functions always in counter-clockwise order (which the code in the course notes requires). Although he had fixed his code up for this, we saw no reason why the vertices couldn't always be given in counter-clockwise order. So, to make life easier for the students, I decided to change the code to support this requirement. Now in the process, I cleaned up a few other things, and did some testing, and at about 2:00 PM mailed everyone saying "recopy your files". No problem, right?

Well, not until 5:00 when I realized that I had introduced 3 very minor bugs by making the changes -- so minor that it didn't deserve another "recopy your files" message. But it taught me a good lesson: you should link into the class files instead of copying them locally. Who knows when I will decide to change them next....

In any case, you should remove the common source files that you previously copied (all except Makefile and rasterize.*) and then link back into the class source code.

First, cd to your development directory (i.e., cd ~/cs248/assignment2), and then....

If you are developing in C, type:

rm -f cube.h render.h cube.c geometry.c main.c
ln -s /usr/class/cs248/assignments/assignment2/template/cube.h .
ln -s /usr/class/cs248/assignments/assignment2/template/render.h .
ln -s /usr/class/cs248/assignments/assignment2/template/cube.c .
ln -s /usr/class/cs248/assignments/assignment2/template/geometry.c .
ln -s /usr/class/cs248/assignments/assignment2/template/main.c .
ln -s /usr/class/cs248/assignments/assignment2/maps .

If you are developing in C++, type:

rm -f cube.h render.h cube.cc geometry.cc main.cc
ln -s /usr/class/cs248/assignments/assignment2/template/cube.h .
ln -s /usr/class/cs248/assignments/assignment2/template/render.h .
ln -s /usr/class/cs248/assignments/assignment2/template/cube.cc .
ln -s /usr/class/cs248/assignments/assignment2/template/geometry.cc .
ln -s /usr/class/cs248/assignments/assignment2/template/main.cc .
ln -s /usr/class/cs248/assignments/assignment2/maps .

BTW, in order to get your file dependencies done automatically, type:


make depend

In order to get rid of all the cruddy files, type:

make clean

In order to get rid of all but the source files, type:

make spotless