boundarylayers sides with separate bcnr and option to set surface

index to -1

this fixes 2 issues:

* If extruded outwards in occ and curvature turned on, if sides are
not set to index -1 then they are curved back towards the face again

* If no different facedescriptor is set, blayer.Boundaries() would
wrongly return the whole boundary and not only the layer part of the side.

libsrc/meshing/boundarylayer.cpp

@@ -601,8 +601,11 @@ namespace netgen
     p2sel = mesh.CreatePoint2SurfaceElementTable();
 
     nfd_old = mesh.GetNFD();
+    moved_surfaces.SetSize(nfd_old+1);
+    moved_surfaces.Clear();
     si_map.SetSize(nfd_old+1);
-    si_map = -1;
+    for(auto i : Range(nfd_old+1))
+      si_map[i] = i;
   }
 
   void BoundaryLayerTool :: CreateNewFaceDescriptors()
@@ -610,6 +613,9 @@ namespace netgen
     surfacefacs.SetSize(nfd_old+1);
     surfacefacs = 0.0;
     // create new FaceDescriptors
+    domain_map.SetSize(mesh.GetNDomains()+1);
+    for(auto i : Range(mesh.GetNDomains()+1))
+      domain_map[i] = i;
     for(auto i : Range(1, nfd_old+1))
       {
         const auto& fd = mesh.GetFaceDescriptor(i);
@@ -623,15 +629,53 @@ namespace netgen
                 // -1 surf nr is so that curving does not do anything
                 FaceDescriptor new_fd(-1, isIn ? new_mat_nrs[i] : fd.DomainIn(),
                                       isIn ? fd.DomainOut() : new_mat_nrs[i], -1);
+                domain_map[isIn ? fd.DomainIn() : fd.DomainOut()] = new_mat_nrs[i];
                 new_fd.SetBCProperty(new_si);
                 mesh.AddFaceDescriptor(new_fd);
                 si_map[i] = new_si;
+                moved_surfaces.SetBit(i);
                 mesh.SetBCName(new_si-1, "mapped_" + name);
               }
           }
       }
   }
 
+  void BoundaryLayerTool ::CreateFaceDescriptorsSides()
+  {
+    BitArray face_done(mesh.GetNFD()+1);
+    face_done.Clear();
+    for(const auto& sel : mesh.SurfaceElements())
+      {
+        auto facei = sel.GetIndex();
+        if(face_done.Test(facei))
+          continue;
+        bool point_moved = false;
+        bool point_fixed = false;
+        for(auto pi : sel.PNums())
+          {
+            if(growthvectors[pi].Length() > 0)
+              point_moved = true;
+            else
+              point_fixed = true;
+          }
+        if(point_moved && point_fixed)
+          {
+            int new_si = mesh.GetNFD()+1;
+            const auto& fd = mesh.GetFaceDescriptor(facei);
+            auto isIn = domains.Test(fd.DomainIn());
+            auto isOut = domains.Test(fd.DomainOut());
+            int si = params.sides_keep_surfaceindex ? facei : -1;
+            FaceDescriptor new_fd(si, domain_map[fd.DomainIn()],
+                                  domain_map[fd.DomainOut()], si);
+            new_fd.SetBCProperty(new_si);
+            mesh.AddFaceDescriptor(new_fd);
+            si_map[facei] = new_si;
+            mesh.SetBCName(new_si-1, fd.GetBCName());
+            face_done.SetBit(facei);
+          }
+      }
+  }
+
   void BoundaryLayerTool :: CalculateGrowthVectors()
   {
     growthvectors.SetSize(np);
@@ -777,7 +821,7 @@ namespace netgen
       {
         if(segs_done[si]) continue;
         const auto& segi = segments[si];
-        if(si_map[segi.si] == -1) continue;
+        if(!moved_surfaces.Test(segi.si)) continue;
         segs_done.SetBit(si);
         segmap[si].Append(make_pair(si, 0));
         moved_segs.Append(si);
@@ -791,7 +835,7 @@ namespace netgen
               {
                 segs_done.SetBit(sj);
                 int type;
-                if(si_map[segj.si] != -1)
+                if(moved_surfaces.Test(segj.si))
                   type = 0;
                 else if(const auto& fd = mesh.GetFaceDescriptor(segj.si); domains.Test(fd.DomainIn()) && domains.Test(fd.DomainOut()))
                   {
@@ -1067,7 +1111,7 @@ namespace netgen
                             sel.GeomInfo()[i].u = 0.0;
                             sel.GeomInfo()[i].v = 0.0;
                         }
-                        sel.SetIndex(segj.si);
+                        sel.SetIndex(si_map[segj.si]);
                         mesh.AddSurfaceElement(sel);
 
                         // TODO: Too many, would be enough to only add outermost ones
@@ -1117,7 +1161,7 @@ namespace netgen
       {
         // copy because surfaceels array will be resized!
         auto sel = mesh[si];
-        if(si_map[sel.GetIndex()] != -1)
+        if(moved_surfaces.Test(sel.GetIndex()))
           {
             Array<PointIndex> points(sel.PNums());
             if(surfacefacs[sel.GetIndex()] > 0) Swap(points[0], points[2]);
@@ -1318,7 +1362,7 @@ namespace netgen
   void BoundaryLayerTool :: SetDomInOut()
   {
     for(auto i : Range(1, nfd_old+1))
-      if(si_map[i] != -1)
+      if(moved_surfaces.Test(i))
         {
           if(auto dom = mesh.GetFaceDescriptor(si_map[i]).DomainIn(); dom > ndom_old)
             mesh.GetFaceDescriptor(i).SetDomainOut(dom);
@@ -1392,6 +1436,7 @@ namespace netgen
   {
       CreateNewFaceDescriptors();
       CalculateGrowthVectors();
+      CreateFaceDescriptorsSides();
       auto segmap = BuildSegMap();
 
       auto in_surface_direction = ProjectGrowthVectorsOnSurface();

libsrc/meshing/boundarylayer.hpp

@@ -19,6 +19,7 @@ public:
   bool outside = false; // set the boundary layer on the outside
   bool grow_edges = false;
   bool limit_growth_vectors = true;
+  bool sides_keep_surfaceindex = false;
   Array<size_t> project_boundaries;
 };
 
@@ -44,6 +45,8 @@ class BoundaryLayerTool
     Array<SegmentIndex> moved_segs;
     int max_edge_nr, nfd_old, ndom_old;
     Array<int> new_mat_nrs;
+    Array<int> domain_map;
+    BitArray moved_surfaces;
     int np, nseg, nse, ne;
     double height;
 
@@ -56,6 +59,7 @@ class BoundaryLayerTool
 
     // major steps called in Perform()
     void CreateNewFaceDescriptors();
+    void CreateFaceDescriptorsSides();
     void CalculateGrowthVectors();
     Array<Array<pair<SegmentIndex, int>>, SegmentIndex> BuildSegMap();
 

libsrc/meshing/python_mesh.cpp

@@ -1309,7 +1309,8 @@ DLL_HEADER void ExportNetgenMeshing(py::module &m)
                               variant<string, map<string, string>> material,
                               variant<string, int> domain, bool outside,
                               optional<string> project_boundaries,
-                              bool grow_edges, bool limit_growth_vectors)
+                              bool grow_edges, bool limit_growth_vectors,
+                              bool sides_keep_surfaceindex)
            {
              BoundaryLayerParameters blp;
              BitArray boundaries(self.GetNFD()+1);
@@ -1394,12 +1395,13 @@ DLL_HEADER void ExportNetgenMeshing(py::module &m)
              blp.outside = outside;
              blp.grow_edges = grow_edges;
              blp.limit_growth_vectors = limit_growth_vectors;
+             blp.sides_keep_surfaceindex = sides_keep_surfaceindex;
 
              GenerateBoundaryLayer (self, blp);
              self.UpdateTopology();
            }, py::arg("boundary"), py::arg("thickness"), py::arg("material"),
           py::arg("domains") = ".*", py::arg("outside") = false,
-          py::arg("project_boundaries")=nullopt, py::arg("grow_edges")=true, py::arg("limit_growth_vectors") = true,
+          py::arg("project_boundaries")=nullopt, py::arg("grow_edges")=true, py::arg("limit_growth_vectors") = true, py::arg("sides_keep_surfaceindex")=false,
           R"delimiter(
 Add boundary layer to mesh.