Two classic out-of-print books on generative systems online for free perusal in PDF format:
- Prusinkiewicz & Lindenmayer: The Algorithmic Beauty of Plants
Classic text on the algorithmic modelling of plants, using formal grammars known as L-systems. This very comprehensive book describes models of varying complexity, from single leaves to flowers and finally trees etc. L-systems were invented by Lindenmayer in 1968 to model the morphology of various organisms, for more information see the wikipedia definition: L-system.
The Algorithmic Botany site where the book is available is the website of the Biological Modeling and Visualization research group at the University of Calgary, and contains numerous related papers and resources.
- John Frazer: An Evolutionary Architecture
In this book, John Frazer describes 30 years of work with evolutionary strategies for form-generating processes. Coming out of the interest in system-based architecture in the 1960s, Frazer and colleagues propose organic architectural systems inspired by artificial life and shape grammars.