In order to successfully compile and use the Cal3D library, you need the following programs:
A C++ compiler with decent STL support.
Doxygen if you want to build the Cal3D API Reference from the sourcecode comments.
The DocBook tools if you want to build this User's Guide from scratch.
The setup was tested on most GNU/Linux distributions and native packages exist for most of them. It also works on all known windows or macos flavors.
Note that you will need additional programs and libraries to compile and run the tools and demos from the Cal3D project. See their documentation for details.