[Gmsh] boolean operations on STL files

[Juan E. Sanchez]

Hello,

I am having issues reading in STL files and performing Boolean 
operations using Gmsh 3.0.5 for Mac OS X.

SetFactory("OpenCASCADE");
Merge "stlimport_part1.stl";
Merge "stlimport_part2.STL";
Merge "stlimport_part3.STL";
Merge "stlimport_part4.STL";

//+
Surface Loop(1) = {1};
Surface Loop(2) = {2};
Surface Loop(3) = {3};
Surface Loop(4) = {4};

//+
Volume(1) = {1};
Volume(2) = {2};
Volume(3) = {3};
Volume(4) = {4};


The OCC kernel fails to see the surfaces and volumes I have created from 
the files:

Error   : '/Users/foo/Desktop/foo.geo', line 8 : Could not add surface loop
Error   : Unknown OpenCASCADE face with tag 2
Error   : '/Users/foo/Desktop/foo.geo', line 9 : Could not add surface loop
Error   : Unknown OpenCASCADE face with tag 3
Error   : '/Users/foo/Desktop/foo.geo', line 10 : Could not add surface loop
Error   : Unknown OpenCASCADE face with tag 4
Error   : '/Users/foo/Desktop/foo.geo', line 11 : Could not add surface loop
Error   : Unknown OpenCASCADE surface loop with tag 1
Error   : '/Users/foo/Desktop/foo.geo', line 14 : Could not add volume
Error   : Unknown OpenCASCADE surface loop with tag 2
Error   : '/Users/foo/Desktop/foo.geo', line 15 : Could not add volume
Error   : Unknown OpenCASCADE surface loop with tag 3
Error   : '/Users/foo/Desktop/foo.geo', line 16 : Could not add volume
Error   : Unknown OpenCASCADE surface loop with tag 4
Error   : '/Users/foo/Desktop/foo.geo', line 17 : Could not add volume

What is the proper approach for using STL 2D surfaces with boolean 
operations?

Regards,

Juan