program example for interactive 3D-Line?

[Hmooslechner]

Does anybody know where i can get a program-example for a "growing" interactive 3D-Line?

I would like to porgram a 3D-Interactive railing part for following stairs and levels in 3d. (The railings schould not only end at the end of the stairs... but follow the openings at the next level.)


To make it easier to do things like this..
https://www.dropbox.com/s/lgenl5i4itjollf/GelaenderBeispiel.jpg

german tutorial..
http://www.youtube.com/watch?v=FqQpfrR_EQc&feature=youtu.be