Fem: Add option to use old Netgen mesher implementation

src/Mod/Fem/Gui/CMakeLists.txt

@@ -400,6 +400,7 @@ SET(FemGuiPythonUI_SRCS
     Resources/ui/ConstraintTie.ui
     Resources/ui/ConstraintSectionPrint.ui
     Resources/ui/CurrentDensity.ui
+    Resources/ui/DlgSettingsNetgen.ui
     Resources/ui/ElectrostaticPotential.ui
     Resources/ui/ElementFluid1D.ui
     Resources/ui/ElementGeometry1D.ui

src/Mod/Fem/Gui/Resources/Fem.qrc

@@ -123,6 +123,7 @@
         <file>ui/ConstraintSectionPrint.ui</file>
         <file>ui/ConstraintTie.ui</file>
         <file>ui/CurrentDensity.ui</file>
+        <file>ui/DlgSettingsNetgen.ui</file>
         <file>ui/ElectrostaticPotential.ui</file>
         <file>ui/ElementFluid1D.ui</file>
         <file>ui/ElementGeometry1D.ui</file>

src/Mod/Fem/Gui/Resources/ui/DlgSettingsNetgen.ui

@@ -0,0 +1,66 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>Gui::Dialog::DlgSettingsNetgen</class>
+ <widget class="QWidget" name="Gui::Dialog::DlgSettingsNetgen">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>500</width>
+    <height>560</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Netgen</string>
+  </property>
+  <layout class="QVBoxLayout">
+   <item>
+    <widget class="QGroupBox" name="groupBox_1">
+     <property name="title">
+      <string>Netgen</string>
+     </property>
+     <layout class="QGridLayout" name="gridLayout_1">
+      <item row="0" column="0">
+       <widget class="Gui::PrefCheckBox" name="ckb_legacy">
+        <property name="toolTip">
+         <string>Use legacy Netgen object implementation</string>
+        </property>
+        <property name="layoutDirection">
+         <enum>Qt::LeftToRight</enum>
+        </property>
+        <property name="checked">
+         <bool>true</bool>
+        </property>
+        <property name="text">
+         <string>Legacy Netgen</string>
+        </property>
+        <property name="prefEntry" stdset="0">
+         <cstring>UseLegacyNetgen</cstring>
+        </property>
+        <property name="prefPath" stdset="0">
+         <cstring>Mod/Fem/Netgen</cstring>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </item>
+   <item>
+    <spacer name="verticalSpacer_1">
+     <property name="orientation">
+      <enum>Qt::Vertical</enum>
+     </property>
+    </spacer>
+   </item>
+  </layout>
+ </widget>
+ <customwidgets>
+  <customwidget>
+   <class>Gui::PrefCheckBox</class>
+   <extends>QCheckBox</extends>
+   <header>Gui/PrefWidgets.h</header>
+  </customwidget>
+ </customwidgets>
+ <resources/>
+ <connections/>
+</ui>

src/Mod/Fem/InitGui.py

@@ -72,6 +72,8 @@ class FemWorkbench(Workbench):
         import FemGui
         import femcommands.commands
 
+        FreeCADGui.addPreferencePage(":/ui/DlgSettingsNetgen.ui", "FEM")
+
         # dummy usage to get flake8 and lgtm quiet
         False if Fem.__name__ else True
         False if FemGui.__name__ else True

src/Mod/Fem/ObjectsFem.py

@@ -537,6 +537,13 @@ def makeMeshNetgen(doc, name="MeshNetgen"):
     return obj
 
 
+def makeMeshNetgenLegacy(doc, name="MeshNetgen"):
+    """makeMeshNetgenLegacy(document, [name]):
+    makes a old implementation Netgen FEM mesh object"""
+    obj = doc.addObject("Fem::FemMeshShapeNetgenObject", name)
+    return obj
+
+
 def makeMeshRegion(doc, base_mesh, element_length=0.0, name="MeshRegion"):
     """makeMeshRegion(document, base_mesh, [element_length], [name]):
     creates a FEM mesh refinement object to define properties for a refinement of a FEM mesh

src/Mod/Fem/femcommands/commands.py

@@ -817,14 +817,20 @@ class _MeshNetgenFromShape(CommandManager):
     def Activated(self):
         # a mesh could be made with and without an analysis,
         # we're going to check not for an analysis in command manager module
+        netgen_prefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Fem/Netgen")
         FreeCAD.ActiveDocument.openTransaction("Create FEM mesh Netgen")
         mesh_obj_name = "FEMMeshNetgen"
         # if requested by some people add Preference for this
         # mesh_obj_name = sel[0].Name + "_Mesh"
         FreeCADGui.addModule("ObjectsFem")
-        FreeCADGui.doCommand(
-            "ObjectsFem.makeMeshNetgen(FreeCAD.ActiveDocument, '" + mesh_obj_name + "')"
-        )
+        if netgen_prefs.GetBool("UseLegacyNetgen", 1):
+            FreeCADGui.doCommand(
+                "ObjectsFem.makeMeshNetgenLegacy(FreeCAD.ActiveDocument, '" + mesh_obj_name + "')"
+            )
+        else:
+            FreeCADGui.doCommand(
+                "ObjectsFem.makeMeshNetgen(FreeCAD.ActiveDocument, '" + mesh_obj_name + "')"
+            )
         FreeCADGui.doCommand(
             "FreeCAD.ActiveDocument.ActiveObject.Shape = FreeCAD.ActiveDocument.{}".format(
                 self.selobj.Name

src/Mod/Fem/femtest/app/test_object.py

@@ -241,6 +241,9 @@ class TestObjectType(unittest.TestCase):
         self.assertEqual("Fem::MeshGroup", type_of_obj(ObjectsFem.makeMeshGroup(doc, mesh)))
         self.assertEqual("Fem::MeshRegion", type_of_obj(ObjectsFem.makeMeshRegion(doc, mesh)))
         self.assertEqual("Fem::FemMeshNetgen", type_of_obj(ObjectsFem.makeMeshNetgen(doc)))
+        self.assertEqual(
+            "Fem::FemMeshShapeNetgenObject", type_of_obj(ObjectsFem.makeMeshNetgenLegacy(doc))
+        )
         self.assertEqual("Fem::MeshResult", type_of_obj(ObjectsFem.makeMeshResult(doc)))
         self.assertEqual("Fem::ResultMechanical", type_of_obj(ObjectsFem.makeResultMechanical(doc)))
         solverelmer = ObjectsFem.makeSolverElmer(doc)
@@ -408,6 +411,9 @@ class TestObjectType(unittest.TestCase):
         self.assertTrue(is_of_type(ObjectsFem.makeMeshGroup(doc, mesh), "Fem::MeshGroup"))
         self.assertTrue(is_of_type(ObjectsFem.makeMeshRegion(doc, mesh), "Fem::MeshRegion"))
         self.assertTrue(is_of_type(ObjectsFem.makeMeshNetgen(doc), "Fem::FemMeshNetgen"))
+        self.assertTrue(
+            is_of_type(ObjectsFem.makeMeshNetgenLegacy(doc), "Fem::FemMeshShapeNetgenObject")
+        )
         self.assertTrue(is_of_type(ObjectsFem.makeMeshResult(doc), "Fem::MeshResult"))
         self.assertTrue(is_of_type(ObjectsFem.makeResultMechanical(doc), "Fem::ResultMechanical"))
         solverelmer = ObjectsFem.makeSolverElmer(doc)
@@ -744,6 +750,9 @@ class TestObjectType(unittest.TestCase):
         mesh_netgen = ObjectsFem.makeMeshNetgen(doc)
         self.assertTrue(is_derived_from(mesh_netgen, "App::DocumentObject"))
         self.assertTrue(is_derived_from(mesh_netgen, "Fem::FemMeshShapeBaseObjectPython"))
+        mesh_netgen = ObjectsFem.makeMeshNetgenLegacy(doc)
+        self.assertTrue(is_derived_from(mesh_netgen, "App::DocumentObject"))
+        self.assertTrue(is_derived_from(mesh_netgen, "Fem::FemMeshShapeNetgenObject"))
 
         # MeshResult
         mesh_result = ObjectsFem.makeMeshResult(doc)
@@ -972,6 +981,9 @@ class TestObjectType(unittest.TestCase):
         self.assertTrue(
             ObjectsFem.makeMeshNetgen(doc).isDerivedFrom("Fem::FemMeshShapeBaseObjectPython")
         )
+        self.assertTrue(
+            ObjectsFem.makeMeshNetgenLegacy(doc).isDerivedFrom("Fem::FemMeshShapeNetgenObject")
+        )
         self.assertTrue(ObjectsFem.makeMeshResult(doc).isDerivedFrom("Fem::FemMeshObjectPython"))
         self.assertTrue(
             ObjectsFem.makeResultMechanical(doc).isDerivedFrom("Fem::FemResultObjectPython")
@@ -1081,6 +1093,7 @@ def create_all_fem_objects_doc(doc):
     ObjectsFem.makeMeshGroup(doc, msh)
     ObjectsFem.makeMeshRegion(doc, msh)
     analysis.addObject(ObjectsFem.makeMeshNetgen(doc))
+    analysis.addObject(ObjectsFem.makeMeshNetgenLegacy(doc))
     rm = ObjectsFem.makeMeshResult(doc)
 
     res = analysis.addObject(ObjectsFem.makeResultMechanical(doc))[0]