[FEM] proper support for Gmsh HighOrder optimization

There are 4 optimizers available while we only supported 1. This PR adds support for all.

src/Mod/Fem/femmesh/gmshtools.py

@@ -125,6 +125,21 @@ def __init__(self, gmsh_mesh_obj, analysis=None):
         else:
             self.algorithm3D = "1"
 
+        # HighOrderOptimize
+        optimizers = self.mesh_obj.HighOrderOptimize
+        if optimizers == "None":
+            self.HighOrderOptimize = "0"
+        elif optimizers == "Optimization":
+            self.HighOrderOptimize = "1"
+        elif optimizers == "Elastic+Optimization":
+            self.HighOrderOptimize = "2"
+        elif optimizers == "Elastic":
+            self.HighOrderOptimize = "3"
+        elif optimizers == "Fast Curving":
+            self.HighOrderOptimize = "4"
+        else:
+            self.HighOrderOptimize = "0"
+
         # mesh groups
         if self.mesh_obj.GroupsOfNodes is True:
             self.group_nodes_export = True
@@ -767,16 +782,11 @@ def write_geo(self):
         else:
             geo.write("Mesh.OptimizeNetgen = 0;\n")
         # higher order mesh optimizing
-        if hasattr(self.mesh_obj, "HighOrderOptimize") and self.mesh_obj.HighOrderOptimize is True:
-            geo.write(
-                "Mesh.HighOrderOptimize = 1; // for more HighOrderOptimize "
-                "parameter check http://gmsh.info/doc/texinfo/gmsh.html\n"
-            )
-        else:
-            geo.write(
-                "Mesh.HighOrderOptimize = 0; // for more HighOrderOptimize "
-                "parameter check http://gmsh.info/doc/texinfo/gmsh.html\n"
-            )
+        geo.write(
+            "// High-order meshes optimization (0=none, 1=optimization, 2=elastic+optimization, "
+            "3=elastic, 4=fast curving)\n"
+        )
+        geo.write("Mesh.HighOrderOptimize = " + self.HighOrderOptimize + ";\n")
         geo.write("\n")
 
         geo.write("// mesh order\n")
@@ -850,7 +860,7 @@ def write_geo(self):
         # some useful information
         geo.write("// " + "*" * 70 + "\n")
         geo.write("// Gmsh documentation:\n")
-        geo.write("// http://gmsh.info/doc/texinfo/gmsh.html#Mesh\n")
+        geo.write("// https://gmsh.info/doc/texinfo/gmsh.html#Mesh\n")
         geo.write("//\n")
         geo.write(
             "// We do not check if something went wrong, like negative "

src/Mod/Fem/femobjects/mesh_gmsh.py

@@ -60,16 +60,34 @@ class MeshGmsh(base_fempythonobject.BaseFemPythonObject):
         "R-tree",
         "HXT"
     ]
+    known_mesh_HighOrderOptimizers = [
+        "None",
+        "Optimization",
+        "Elastic+Optimization",
+        "Elastic",
+        "Fast curving"
+    ]
 
     def __init__(self, obj):
         super(MeshGmsh, self).__init__(obj)
         self.add_properties(obj)
 
     def onDocumentRestored(self, obj):
+        # HighOrderOptimize was once App::PropertyBool, so check this
+        HighOrderOptimizer = ""
+        if obj.HighOrderOptimize is True:
+            HighOrderOptimizer = "Optimization"
+            obj.removeProperty("HighOrderOptimize")
+        elif obj.HighOrderOptimize is False:
+            HighOrderOptimizer = "None"
+            obj.removeProperty("HighOrderOptimize")
         self.add_properties(obj)
         # refresh the list of known 3D algorithms for existing meshes
         # since some algos are meanwhile deprecated and new algos are available
         obj.Algorithm3D = MeshGmsh.known_mesh_algorithm_3D
+        # write the stored HighOrderOptimizer
+        if HighOrderOptimizer:
+            obj.HighOrderOptimize = HighOrderOptimizer
 
     def add_properties(self, obj):
         if not hasattr(obj, "MeshBoundaryLayerList"):
@@ -166,12 +184,13 @@ def add_properties(self, obj):
 
         if not hasattr(obj, "HighOrderOptimize"):
             obj.addProperty(
-                "App::PropertyBool",
+                "App::PropertyEnumeration",
                 "HighOrderOptimize",
                 "FEM Gmsh Mesh Params",
-                "Optimize high order meshes"
+                "Optimization of high order meshes"
             )
-            obj.HighOrderOptimize = False
+            obj.HighOrderOptimize = MeshGmsh.known_mesh_HighOrderOptimizers
+            obj.HighOrderOptimize = "None"
 
         if not hasattr(obj, "RecombineAll"):
             obj.addProperty(
@@ -232,7 +251,7 @@ def add_properties(self, obj):
                 "mesh algorithm 2D"
             )
             obj.Algorithm2D = MeshGmsh.known_mesh_algorithm_2D
-            obj.Algorithm2D = "Automatic"  # ?
+            obj.Algorithm2D = "Automatic"
 
         if not hasattr(obj, "Algorithm3D"):
             obj.addProperty(
@@ -242,7 +261,7 @@ def add_properties(self, obj):
                 "mesh algorithm 3D"
             )
             obj.Algorithm3D = MeshGmsh.known_mesh_algorithm_3D
-            obj.Algorithm3D = "Automatic"  # ?
+            obj.Algorithm3D = "Automatic"
 
         if not hasattr(obj, "GroupsOfNodes"):
             obj.addProperty(

src/Mod/Fem/femtest/data/elmer/group_mesh.geo

@@ -19,7 +19,8 @@ Mesh.MeshSizeFromCurvature = 12; // number of elements per 2*pi radians, 0 to de
 // optimize the mesh
 Mesh.Optimize = 1;
 Mesh.OptimizeNetgen = 0;
-Mesh.HighOrderOptimize = 0; // for more HighOrderOptimize parameter check http://gmsh.info/doc/texinfo/gmsh.html
+// High-order meshes optimization (0=none, 1=optimization, 2=elastic+optimization, 3=elastic, 4=fast curving)
+Mesh.HighOrderOptimize = 0;
 
 // mesh order
 Mesh.ElementOrder = 2;
@@ -45,7 +46,7 @@ Save "/tmp/tmpjVhNNb.unv";
 
 // **********************************************************************
 // Gmsh documentation:
-// http://gmsh.info/doc/texinfo/gmsh.html#Mesh
+// https://gmsh.info/doc/texinfo/gmsh.html#Mesh
 //
 // We do not check if something went wrong, like negative jacobians etc. You can run Gmsh manually yourself: 
 //

src/Mod/MeshPart/Gui/Tessellation.cpp

@@ -514,7 +514,7 @@ bool Mesh2ShapeGmsh::writeProject(QString& inpFile, QString& outFile)
                 << "// optimize the mesh\n"
                 << "Mesh.Optimize = 1;\n"
                 << "Mesh.OptimizeNetgen = 0;\n"
-                << "// for more HighOrderOptimize parameter check http://gmsh.info/doc/texinfo/gmsh.html\n"
+                << "// High-order meshes optimization (0=none, 1=optimization, 2=elastic+optimization, 3=elastic, 4=fast curving)\n"
                 << "Mesh.HighOrderOptimize = 0;\n\n"
                 << "// mesh order\n"
                 << "Mesh.ElementOrder = 2;\n"