Here is an applet which demonstrates the principles of the z-buffer algorithm
Follow the steps to create the result of superposition of the segments
All those developments are released under Cecill licence.
The project Forms Generator is available on a svn, contact me for more information. In the future, a project might be created on sourceforge.
Projects svg 3d, XSD to RelaxNG converter, javascript SAX parser, javascript RelaxNG validator, javascript datatype library are published on Google code. Project javascript SAX parser is also published on Github.