Roof orientation - does CityEngine forget?

Discussion created by BTLeslie on Aug 30, 2013
Latest reply on Sep 2, 2013 by MBuehler-esristaff

I have drawn 440 building footprints in CityEngine.  I have taken care with the edge I have drawn first to help me control the orientation of gable and shed roofs.  In case I have made a mistake with the first edge I have added a 'roofIndex' attribute so I can change the orientation of the roof where necessary.

I have found that when I re-open the project some of the roofs have changed their orientation since I saved the file - I'm not sure how many buildings have changed because the effect is mainly quite subtle but in the case of long-thin buildings with a shed roof the effect is very obvious because the roof becomes enormous.

Is this a known problem (2011.2)?
Does CityEngine forget which edge was drawn first?
Does it forget the change to my 'roofIndex' parameter? 
Would it remember the first edge better if I used imported shapefiles?
Could I be doing something wrong?

It's very difficult for me to spot a pattern to this because it's difficult to be sure where it is happening.