Xfrog, one of the modelling systems that are presented in our book, was created by the authors over the last years. Currently it is distributed by Greenworks Organics Software. The program combines rule-based and procedural modelling aspects and therefor is quite elegant for modelling.

• official website Greenworks Organic Software
• get a trial version of xfrog
• a description of the program (from the book): here
• a tutorial from the book (applies to xfrog 3.5) here
• tutorials are also found at Greenworks