Just to comment on the proposed CGAL solution:
Finally, I wrote a stand alone applications that would take a .STL and a,b,c,d plane parameters, split the mesh and save the resulting mesh(es) in files. I did not have the time nor the experience to write Python wrapper around the CGAL code. I also wrote a Python function that would do the following steps:
- Create a temporary directory
- Save the mesh to split in this directory
- Call my CGALTrimming .exe with the right parameters in a subprocess.Popen(…) command and wait for it to finish
- Import back the splitted meshes.
- Delete the temporary directory and its content.
Unfortunately, I cannot share the executable or the code due to licensing restrictions. Again, if Rhino could base their core geometric mesh algorithms on such robust library, they would save the trouble to ALL their users!