I am trying to do a CAD Viewer project and want to import 3d format of PRO/E and UG,etc(such like that),so far I can import 3ds ,dxf and obj now.Could u please offer me some web link with the relevant code for PRO/E and UG ?Thanks a lot!
File formats of CAD apps are well kept secrets most of the time. It’s part of their intellectual property.
If the file contains parametric descriptions (which I would expect from a company which has Parametric in its name 
) you’d need your own tesselator.
Expect some formats to be compressed, too.