Check out and build from Subversion

(This part assumes Windows users are using Cygwin. If you aren't, TortoiseSVN is a good client.)

1. Change into a directory that you want the tree to be kept in.
2. Check out the source tree:
   svn co svn://svn.icculus.org/quake3/trunk quake3
   (You can check out a specific revision with the -r option, like this: svn co svn://svn.icculus.org/quake3/trunk quake3 -r100)
3. Read the readme file. Really. Do it.
4. Compile and install Quake 3:

   • Linux and friends

     1. Install Quake 3 for Linux using the latest point release installer. While the Quake3 engine is Free Software, you still need to copy over legal PK3s like before.
     2. Change into the top level directory (it contains the ui and code directories.)
     3. Run make.
     4. Set $COPYDIR to the directory you installed Quake3 to and make the copyfiles target. Make sure you are changed to the owner of this path (probably root).
        COPYDIR="/opt/quake3" make copyfiles

   • Windows

     Building on Windows is slightly complicated. You can either use Microsoft Visual C++ or MinGW. MinGW works better currently; both methods are described in the readme you already are supposed to have read.

5. If everything has gone well, you should have a binary that works! If not, seek help.

Pay your dues, contribute!

If you've come up with an improvement or fixed something, we'd love to hear about it! Firstly, try to make sure that the patch breaks less than it fixes. We don't require everyone to be decorated Geniuses, but do attempt to produce a patch that you've tested and at list sort-of understand what you're doing.

Not everyone who knows C knows how to use diff (the tool you need to create patches with), and not everyone is making patches against the C code. That's okay, here's the 10¢ survival guide to making patches:

• Create a patch named amazing_new_feature.patch between oldfile and newfile:
  diff -u oldfile newfile > amazing_new_feature.patch
• Create a patch named amazing_new_features.patch between directory olddir and newdir:
  diff -Naur olddir newdir > amazing_new_features.patch
• Apply a patch amazing_new_feature.patch:
  patch -p0 -i amazing_new_feature.patch

For more information on diff and patch, read their man-pages.

The prefered way to get the ball rolling on a patch is to file a bug for your request with the patch attached to it and then send a notice to the mailing list about it. If you're really so lazy that you can't do this, we would prefer you at least mail it to zakk@icculus.org rather than not do anything.