Rethinking BIM is a kinda awesome new BIM site - you should definitely check it out.

There are lots of videos and downloads available. Some of this stuff looks like it has been collected or derived from the blogosphere or web in general.

One recent post provides an example file that can help you to find the surface normal in an Adaptive Component
Image from Rethinking BIM

Download the File From Here:
Link


via
Finding the Normal in an Adaptive Component

Click here to view the entire blog post.