Does anyone have the description of .3dm file? including the information contained in the file ,and important coordinates of points. Because i must get the topology of the entity to do some calculation. please help,thank you very much!
The 3dm file is a binary file, and it is not advised to read it just like that. Instead, you should use a programming environment and the Rhino SDK (RhinoCommon for C#, VB.NET or Python, or the C++ SDK) to read the file.
For information about software development with Rhino, see http://developer.rhino3d.com/
I think here is a possible start: