FEM: added import/export of mesh as YAML/JSON

src/Mod/Fem/CMakeLists.txt

@@ -52,6 +52,7 @@ SET(FemInOut_SRCS
     feminout/importInpMesh.py
     feminout/importToolsFem.py
     feminout/importVTKResults.py
+    feminout/importYamlJsonMesh.py
     feminout/importZ88Mesh.py
     feminout/importZ88O2Results.py
     feminout/readFenicsXDMF.py
@@ -183,6 +184,7 @@ SET(FemTestsMesh_SRCS
     femtest/testfiles/mesh/tetra10_mesh.inp
     femtest/testfiles/mesh/tetra10_mesh.unv
     femtest/testfiles/mesh/tetra10_mesh.vtk
+    femtest/testfiles/mesh/tetra10_mesh.yml
     femtest/testfiles/mesh/tetra10_mesh.z88
 )
 

src/Mod/Fem/Init.py

@@ -39,6 +39,13 @@
 FreeCAD.addImportType("FEM mesh Fenics (*.xml *.xdmf)", "feminout.importFenicsMesh")
 FreeCAD.addExportType("FEM mesh Fenics (*.xml *.xdmf)", "feminout.importFenicsMesh")
 
+FreeCAD.addImportType(
+    "FEM mesh YAML/JSON (*.meshyaml *.meshjson *.yaml *.json)", "feminout.importYamlJsonMesh"
+)
+FreeCAD.addExportType(
+    "FEM mesh YAML/JSON (*.meshyaml *.meshjson *.yaml *.json)", "feminout.importYamlJsonMesh"
+)
+
 FreeCAD.addImportType("FEM mesh Z88 (*i1.txt)", "feminout.importZ88Mesh")
 FreeCAD.addExportType("FEM mesh Z88 (*i1.txt)", "feminout.importZ88Mesh")
 

src/Mod/Fem/TestFem.py

@@ -117,6 +117,7 @@
 ./bin/FreeCADCmd --run-test "femtest.testmesh.TestMeshEleTetra10.test_tetra10_inp"
 ./bin/FreeCADCmd --run-test "femtest.testmesh.TestMeshEleTetra10.test_tetra10_unv"
 ./bin/FreeCADCmd --run-test "femtest.testmesh.TestMeshEleTetra10.test_tetra10_vkt"
+./bin/FreeCADCmd --run-test "femtest.testmesh.TestMeshEleTetra10.test_tetra10_yml"
 ./bin/FreeCADCmd --run-test "femtest.testmesh.TestMeshEleTetra10.test_tetra10_z88"
 ./bin/FreeCADCmd --run-test "femtest.testobject.TestObjectCreate.test_femobjects_make"
 ./bin/FreeCADCmd --run-test "femtest.testobject.TestObjectType.test_femobjects_type"
@@ -185,6 +186,9 @@
 import unittest
 unittest.TextTestRunner().run(unittest.TestLoader().loadTestsFromName("femtest.testmesh.TestMeshEleTetra10.test_tetra10_vkt"))
 
+import unittest
+unittest.TextTestRunner().run(unittest.TestLoader().loadTestsFromName("femtest.testmesh.TestMeshEleTetra10.test_tetra10_yml"))
+
 import unittest
 unittest.TextTestRunner().run(unittest.TestLoader().loadTestsFromName("femtest.testmesh.TestMeshEleTetra10.test_tetra10_z88"))
 

src/Mod/Fem/feminout/importToolsFem.py

@@ -242,6 +242,96 @@ def make_femmesh(
     return mesh
 
 
+def make_dict_from_femmesh(
+    femmesh
+):
+    """
+    Converts FemMesh into dictionary structure which can immediately used
+    from importToolsFem.make_femmesh(mesh_data) to create a valid FEM mesh.
+    """
+    # this dict can be easily saved and reloaded by yaml
+    # see importYamlJasonMesh for a implementation
+
+    mesh_data = {}
+
+    seg2 = []
+    seg3 = []
+
+    tri3 = []
+    tri6 = []
+    quad4 = []
+    quad8 = []
+
+    tet4 = []
+    tet10 = []
+    hex8 = []
+    hex20 = []
+    pent6 = []
+    pent15 = []
+
+    # associations for lengths of tuples to different
+    # edge, face, and volume elements
+
+    len_to_edge = {2: seg2, 3: seg3}
+    len_to_face = {3: tri3, 6: tri6, 4: quad4, 8: quad8}
+    len_to_volume = {
+        4: tet4,
+        10: tet10,
+        8: hex8,
+        20: hex20,
+        6: pent6,
+        15: pent15
+    }
+
+    # analyze edges
+
+    for e in femmesh.Edges:
+        t = femmesh.getElementNodes(e)
+        len_to_edge[len(t)].append((e, t))
+
+    # analyze faces
+
+    for f in femmesh.Faces:
+        t = femmesh.getElementNodes(f)
+        len_to_face[len(t)].append((f, t))
+
+    # analyze volumes
+
+    for v in femmesh.Volumes:
+        t = femmesh.getElementNodes(v)
+        len_to_volume[len(t)].append((v, t))
+
+    mesh_data = {
+        'Nodes': dict([(k, (v.x, v.y, v.z))
+                       for (k, v) in femmesh.Nodes.items()]),
+        'Seg2Elem': dict(seg2),
+        'Seg3Elem': dict(seg3),
+
+        'Tria3Elem': dict(tri3),
+        'Tria6Elem': dict(tri6),
+        'Quad4Elem': dict(quad4),
+        'Quad8Elem': dict(quad8),
+
+        'Tetra4Elem': dict(tet4),
+        'Tetra10Elem': dict(tet10),
+        'Hexa8Elem': dict(hex8),
+        'Hexa20Elem': dict(hex20),
+        'Penta6Elem': dict(pent6),
+        'Penta15Elem': dict(pent15),
+
+        'Groups': dict([(
+            group_num, (
+                femmesh.getGroupName(group_num),
+                femmesh.getGroupElements(group_num)
+            )
+        ) for group_num in femmesh.Groups])
+
+    }
+    # no pyr5, pyr13?
+    # no groups?
+    return mesh_data
+
+
 def fill_femresult_mechanical(
     res_obj,
     result_set

src/Mod/Fem/feminout/importYamlJsonMesh.py

@@ -0,0 +1,220 @@
+# ***************************************************************************
+# *                                                                         *
+# *   Copyright (c) 2019 - Johannes Hartung <j.hartung@gmx.net>             *
+# *                                                                         *
+# *   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 YAML and JSON mesh reader and writer"
+__author__ = "Johannes Hartung"
+__url__ = "http://www.freecadweb.org"
+
+## @package importYAMLJSONMesh
+#  \ingroup FEM
+#  \brief FreeCAD YAML and JSON Mesh reader and writer for FEM workbench
+
+import json
+import os
+
+import FreeCAD
+from . import importToolsFem
+
+has_yaml = True
+try:
+    import yaml
+except ImportError:
+    FreeCAD.Console.PrintMessage(
+        "No YAML available (import yaml failure), "
+        "yaml import/export won't work\n"
+    )
+    has_yaml = False
+
+
+# ****************************************************************************
+# ********* 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
+
+
+def open(
+    filename
+):
+    '''called when freecad opens a file
+    a FEM mesh object is created in a new document'''
+
+    docname = os.path.splitext(os.path.basename(filename))[0]
+    return insert(filename, docname)
+
+
+def insert(
+    filename,
+    docname
+):
+    '''called when freecad wants to import a file"
+    a FEM mesh object is created in a existing document'''
+
+    try:
+        doc = FreeCAD.getDocument(docname)
+    except NameError:
+        doc = FreeCAD.newDocument(docname)
+    FreeCAD.ActiveDocument = doc
+
+    import_yaml_json_mesh(filename)
+    return doc
+
+
+def export(objectslist, fileString):
+    "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
+
+    write(fileString, obj.FemMesh)
+
+
+# ****************************************************************************
+# ********* module specific methods ******************************************
+# reader:
+# - a method uses a FemMesh instance, creates the FEM mesh document object and
+#     returns this object
+# - a method read the data from file creates FemMesh instance out of the
+#     FEM mesh dictionary. This instance is returned
+# - a converts the raw read data into the FEM mesh dictionary which
+#     can be used to create a FemMesh instance
+#
+#
+# writer:
+# - a method directly writes a FemMesh to the mesh file
+
+# ********* reader ***********************************************************
+def import_yaml_json_mesh(
+    fileString
+):
+    """
+    read a FemMesh from a yaml/json mesh file
+    insert a FreeCAD FEM Mesh object in the ActiveDocument
+    return the FEM mesh document object
+    """
+
+    mesh_name = os.path.basename(os.path.splitext(fileString)[0])
+
+    femmesh = read(fileString)
+    if femmesh:
+        mesh_object = FreeCAD.ActiveDocument.addObject(
+            'Fem::FemMeshObject',
+            mesh_name
+        )
+        mesh_object.FemMesh = femmesh
+
+    return mesh_object
+
+
+def read(
+    fileString
+):
+    '''read a FemMesh from a yaml/json mesh file and return the FemMesh
+    '''
+    # no document object is created, just the FemMesh is returned
+
+    fileExtension = os.path.basename(os.path.splitext(fileString)[1])
+
+    raw_mesh_data = {}
+    if fileExtension.lower() == ".meshjson" or\
+       fileExtension.lower() == ".json":
+        fp = pyopen(fileString, "rt")
+        raw_mesh_data = json.load(fp)
+        fp.close()
+    elif (
+            fileExtension.lower() == ".meshyaml"
+            or fileExtension.lower() == ".meshyml"
+            or fileExtension.lower() == ".yaml"
+            or fileExtension.lower() == ".yml"
+    ) and has_yaml:
+        fp = pyopen(fileString, "rt")
+        raw_mesh_data = yaml.load(fp)
+        fp.close()
+    else:
+        FreeCAD.Console.PrintError(
+            "Unknown extension, "
+            "please select other importer.\n")
+
+    FreeCAD.Console.PrintMessage("Converting indices to integer numbers ...")
+    mesh_data = convert_raw_data_to_mesh_data(raw_mesh_data)
+    FreeCAD.Console.PrintMessage("OK\n")
+
+    return importToolsFem.make_femmesh(mesh_data)
+
+
+def convert_raw_data_to_mesh_data(
+    raw_mesh_data
+):
+    """
+    Converts raw dictionary data from JSON or YAML file to proper dict
+    for importToolsFem.make_femmesh(mesh_data). This is necessary since
+    JSON and YAML save dict keys as strings while make_femmesh expects
+    integers.
+    """
+
+    mesh_data = {}
+    for (type_key, type_dict) in raw_mesh_data.items():
+        if type_key.lower() != "groups":
+            mesh_data[type_key] = dict([
+                (int(k), v) for (k, v) in type_dict.items()
+            ])
+    return mesh_data
+
+
+# ********* writer ***********************************************************
+def write(
+    fileString,
+    fem_mesh
+):
+    '''directly write a FemMesh to a yaml/json mesh file
+    fem_mesh: a FemMesh'''
+
+    mesh_data = importToolsFem.make_dict_from_femmesh(fem_mesh)
+
+    if fileString != "":
+        fileName, fileExtension = os.path.splitext(fileString)
+        if fileExtension.lower() == ".json" \
+                or fileExtension.lower() == ".meshjson":
+            fp = pyopen(fileString, "wt")
+            json.dump(mesh_data, fp, indent=4)
+            fp.close()
+        elif (
+            fileExtension.lower() == ".meshyaml"
+            or fileExtension.lower() == ".meshyml"
+            or fileExtension.lower() == ".yaml"
+            or fileExtension.lower() == ".yml"
+        ) and has_yaml:
+            fp = pyopen(fileString, "wt")
+            yaml.safe_dump(mesh_data, fp)
+            fp.close()

src/Mod/Fem/femtest/testfiles/mesh/tetra10_mesh.yml

@@ -0,0 +1,25 @@
+Groups: {}
+Hexa20Elem: {}
+Hexa8Elem: {}
+Nodes:
+  1: [6.0, 12.0, 18.0]
+  2: [0.0, 0.0, 18.0]
+  3: [12.0, 0.0, 18.0]
+  4: [6.0, 6.0, 0.0]
+  5: [3.0, 6.0, 18.0]
+  6: [6.0, 0.0, 18.0]
+  7: [9.0, 6.0, 18.0]
+  8: [6.0, 9.0, 9.0]
+  9: [3.0, 3.0, 9.0]
+  10: [9.0, 3.0, 9.0]
+Penta15Elem: {}
+Penta6Elem: {}
+Quad4Elem: {}
+Quad8Elem: {}
+Seg2Elem: {}
+Seg3Elem: {}
+Tetra10Elem:
+  1: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+Tetra4Elem: {}
+Tria3Elem: {}
+Tria6Elem: {}