The tessellation code was broken because the vector passed to the vertex callback was being declared as a void_p instead of a c_double * 3 . Not working yet, as I have to figure out a way to have the callbacks use the preferred array data-type for converting the argument. Linux Caffe, however, is closing soon, so I shall have to deal with it another day. My desktop is still rebuilding at home, a little more than halfway through the "extra" packages (beyond xorg).