FEM: mesh export, add export to Python module

src/Mod/Fem/CMakeLists.txt

@@ -72,6 +72,7 @@ SET(FemInOut_SRCS
     feminout/importCcxFrdResults.py
     feminout/importFenicsMesh.py
     feminout/importInpMesh.py
+    feminout/importPyMesh.py
     feminout/importToolsFem.py
     feminout/importVTKResults.py
     feminout/importYamlJsonMesh.py

src/Mod/Fem/Init.py

@@ -27,6 +27,8 @@
 import FreeCAD
 
 
+FreeCAD.addExportType("FEM mesh Python (*.meshpy)", "feminout.importPyMesh")
+
 FreeCAD.addExportType("FEM mesh TetGen (*.poly)", "feminout.convert2TetGen")
 
 # see FemMesh::read() and FemMesh::write() methods in src/Mod/Fem/App/FemMesh.cpp

src/Mod/Fem/feminout/importPyMesh.py

@@ -0,0 +1,148 @@
+# ***************************************************************************
+# *   Copyright (c) 2016 Bernd Hahnebach <bernd@bimstatik.org>              *
+# *                                                                         *
+# *   This file is part of the FreeCAD CAx development system.              *
+# *                                                                         *
+# *   This program is free software; you can redistribute it and/or modify  *
+# *   it under the terms of the GNU Lesser General Public License (LGPL)    *
+# *   as published by the Free Software Foundation; either version 2 of     *
+# *   the License, or (at your option) any later version.                   *
+# *   for detail see the LICENCE text file.                                 *
+# *                                                                         *
+# *   This program is distributed in the hope that it will be useful,       *
+# *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+# *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+# *   GNU Library General Public License for more details.                  *
+# *                                                                         *
+# *   You should have received a copy of the GNU Library General Public     *
+# *   License along with this program; if not, write to the Free Software   *
+# *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
+# *   USA                                                                   *
+# *                                                                         *
+# ***************************************************************************
+
+__title__ = "FreeCAD Python Mesh reader and writer"
+__author__ = "Bernd Hahnebach"
+__url__ = "http://www.freecadweb.org"
+
+## @package importPyMesh
+#  \ingroup FEM
+#  \brief FreeCAD Python Mesh reader and writer for FEM workbench
+
+import FreeCAD
+from femmesh import meshtools
+
+# ************************************************************************************************
+# ********* generic FreeCAD import and export methods ********************************************
+# names are fix given from FreeCAD, these methods are called from FreeCAD
+# they are set in FEM modules Init.py
+
+if open.__module__ == "__builtin__":
+    # because we'll redefine open below (Python2)
+    pyopen = open
+elif open.__module__ == "io":
+    # because we'll redefine open below (Python3)
+    pyopen = open
+
+
+# export mesh to python
+def export(
+    objectslist,
+    filename
+):
+    "called when freecad exports a file"
+    if len(objectslist) != 1:
+        FreeCAD.Console.PrintError("This exporter can only export one object.\n")
+        return
+    obj = objectslist[0]
+    if not obj.isDerivedFrom("Fem::FemMeshObject"):
+        FreeCAD.Console.PrintError("No FEM mesh object selected.\n")
+        return
+    femnodes_mesh = obj.FemMesh.Nodes
+    femelement_table = meshtools.get_femelement_table(obj.FemMesh)
+    if meshtools.is_solid_femmesh(obj.FemMesh):
+        fem_mesh_type = "Solid"
+    elif meshtools.is_face_femmesh(obj.FemMesh):
+        fem_mesh_type = "Face"
+    elif meshtools.is_edge_femmesh(obj.FemMesh):
+        fem_mesh_type = "Edge"
+    else:
+        FreeCAD.Console.PrintError("Export of this FEM mesh to Python not supported.\n")
+        return
+    f = pyopen(filename, "w")
+    write_python_mesh_to_file(femnodes_mesh, femelement_table, fem_mesh_type, f)
+    f.close()
+
+
+# ************************************************************************************************
+# ********* module specific methods **************************************************************
+# writer:
+# - a method directly writes a FemMesh to the mesh file
+# - a method takes a file handle, mesh data and writes to the file handle
+
+# ********* writer *******************************************************************************
+
+def write(
+    fem_mesh,
+    filename
+):
+    """directly write a FemMesh to a Python mesh file
+    fem_mesh: a FemMesh"""
+
+    if not fem_mesh.isDerivedFrom("Fem::FemMesh"):
+        FreeCAD.Console.PrintError("Not a FemMesh was given as parameter.\n")
+        return
+    femnodes_mesh = fem_mesh.Nodes
+    femelement_table = meshtools.get_femelement_table(fem_mesh)
+    if meshtools.is_solid_femmesh(fem_mesh):
+        fem_mesh_type = "Solid"
+    elif meshtools.is_face_femmesh(fem_mesh):
+        fem_mesh_type = "Face"
+    elif meshtools.is_edge_femmesh(fem_mesh):
+        fem_mesh_type = "Edge"
+    else:
+        FreeCAD.Console.PrintError("Export of this FEM mesh to Python not supported.\n")
+        return
+    f = pyopen(filename, "w")
+    write_python_mesh_to_file(femnodes_mesh, femelement_table, fem_mesh_type, f)
+    f.close()
+
+
+def write_python_mesh_to_file(femnodes_mesh, femelement_table, fem_mesh_type, f):
+
+    mesh_name = "femmesh"
+
+    # nodes
+    f.write("def create_nodes(femmesh):\n")
+    f.write("    # nodes\n")
+    for node in femnodes_mesh:
+        # print(node, ' --> ', femnodes_mesh[node])
+        vec = femnodes_mesh[node]
+        f.write(
+            "    {0}.addNode({1}, {2}, {3}, {4})\n"
+            .format(mesh_name, vec.x, vec.y, vec.z, node)
+        )
+    f.write("    return True\n")
+    f.write("\n\n")
+
+    # elements
+    f.write("def create_elements(femmesh):\n")
+    f.write("    # elements\n")
+    for element in femelement_table:
+        # print(element, ' --> ', femelement_table[element])
+        if fem_mesh_type == "Solid":
+            f.write(
+                "    {0}.addVolume({1}, {2})\n"
+                .format(mesh_name, list(femelement_table[element]), element)
+            )
+        elif fem_mesh_type == "Face":
+            f.write(
+                "    {0}.addFace({1}, {2})\n"
+                .format(mesh_name, list(femelement_table[element]), element)
+            )
+        elif fem_mesh_type == "Edge":
+            f.write(
+                "    {0}.addEdge({1}, {2})\n"
+                .format(mesh_name, list(femelement_table[element]), element)
+            )
+    f.write("    return True\n")