Perspective of shadows and interactions

[JulesVerne]

It isn't hard to find the basic rules of shadows in regards to a lightsource and a horizion, but what about shadows which are obstructed by other objects-- other buildings for instance.

I can't seem to find instruction for this on the net, they all insist on basic examples, as if everyone paints independent objects on a flat plane. Can anyone provide a resource, or examples?

[kev ferrara]

Creative Perspective for Artists and Illustrators goes into some methods for figuring out these shadows using math...

http://www.amazon.com/Creative-Perspective-Artists-Illustrators-Ernest/dp/0486273377

Or use a photo. Or build the model in a 3D program and render an image of it.Or fake it.