I'm new in using esri cityengine 2011 . i red it's tutorials . it was very interesting and helpful for but there is no references or tutorials for how to create cga rules . how can i find tutorial or help about this subject?
This is a link to a presentation given at the recent ESRI Developer Summit: Developing with ESRI CityEngine.
There are also some video tutorials here:
The CityEngine help also contains an introduction to the principles of CGA.
You can find it in Help Menu -> Help Contents -> Manual -> Rule-based Modeling (also available on the web).