* Add nglib demonstrator for OpenCascade geometry "ng_occ.cpp" to the Netgen project tree

nglib/ng_occ.cpp

@@ -0,0 +1,142 @@
+#include <iostream>
+#include <climits>
+
+#include "TopTools_IndexedMapOfShape.hxx"
+#include "TopoDS.hxx"
+#include "TopoDS_Face.hxx"
+#include "TopoDS_Shape.hxx"
+#include "GProp_GProps.hxx"
+#include "BRepGProp.hxx"
+
+using namespace std;
+
+namespace nglib {
+#include <nglib.h>
+}
+
+int main (int argc, char ** argv)
+{
+   using namespace nglib;
+   
+   cout << "Netgen NgLib - OpenCascade Test Case" << endl;
+   
+   if (argc != 2)
+   {
+      cerr << "use: ng_occ <src_step>" << endl;
+      return 1;
+   }
+   
+   // Define pointer to OCC Geometry
+   Ng_OCC_Geometry *occ_geom;
+   
+   Ng_Mesh *occ_mesh;
+   
+   Ng_Meshing_Parameters mp;
+   
+   TopTools_IndexedMapOfShape FMap;
+   
+   Ng_OCC_TopTools_IndexedMapOfShape *occ_fmap = (Ng_OCC_TopTools_IndexedMapOfShape*)&FMap;
+   
+   // Result of Netgen Operations
+   Ng_Result ng_res;
+
+   // Initialise the Netgen Core library
+   Ng_Init();
+
+   // Read in the OCC File
+   occ_geom = Ng_OCC_Load_STEP(argv[1]);
+   if(!occ_geom)
+   {
+      cout << "Error reading in STEP File: " << argv[1] << endl;
+	  return 1;
+   }
+   cout << "Successfully loaded STEP File: " << argv[1] << endl;
+
+   occ_mesh = Ng_NewMesh();
+   
+   ng_res = Ng_OCC_GetFMap(occ_geom,occ_fmap);
+
+   cout << "ng_res = " << ng_res << endl;
+	  
+   if(!FMap.Extent())
+   {
+      cout << "Error retrieving Face map...." << endl;
+	  return 1;
+   }
+
+   cout << "Successfully extracted the Face Map....:" << FMap.Extent() << endl;
+   
+   for(int i = 1; i <= FMap.Extent(); i++)
+   {
+      TopoDS_Face OCCface;
+	  OCCface = TopoDS::Face(FMap.FindKey(i));
+	  
+	  GProp_GProps faceProps;
+	  BRepGProp::SurfaceProperties(OCCface,faceProps);
+	  
+      cout << "Index: " << i 
+	       << " :: Area: " << faceProps.Mass() 
+		   << " :: Hash: " << OCCface.HashCode(1e+6) 
+		   << endl;
+   }	 
+   
+   mp.uselocalh = 1;
+   mp.elementsperedge = 2.0;
+   mp.elementspercurve = 2.0;
+   mp.maxh = 10.0;
+   mp.grading = 0.2;   
+   mp.closeedgeenable = 0;
+   mp.closeedgefact = 1.0;
+   mp.optsurfmeshenable = 1;
+   
+   
+   cout << "Setting Local Mesh size....." << endl;
+   cout << "OCC Mesh Pointer before call = " << occ_mesh << endl;
+   Ng_OCC_SetLocalMeshSize(occ_geom, occ_mesh, &mp);
+   cout << "Local Mesh size successfully set....." << endl;
+      cout << "OCC Mesh Pointer after call = " << occ_mesh << endl;
+   
+   cout << "Creating Edge Mesh....." << endl;
+   ng_res = Ng_OCC_GenerateEdgeMesh(occ_geom, occ_mesh, &mp);
+   if(ng_res != NG_OK)
+   {
+      Ng_DeleteMesh(occ_mesh);
+	  cout << "Error creating Edge Mesh.... Aborting!!" << endl;
+	  return 1;
+   }
+   else
+   {
+      cout << "Edge Mesh successfully created....." << endl;
+	  cout << "Number of points = " << Ng_GetNP(occ_mesh) << endl;
+   }
+
+   cout << "Creating Surface Mesh....." << endl;
+ 
+   ng_res = Ng_OCC_GenerateSurfaceMesh(occ_geom, occ_mesh, &mp);
+   if(ng_res != NG_OK)
+   {
+      Ng_DeleteMesh(occ_mesh);
+	  cout << "Error creating Surface Mesh..... Aborting!!" << endl;
+	  return 1;
+   }
+   else
+   {
+      cout << "Surface Mesh successfully created....." << endl;
+	  cout << "Number of points = " << Ng_GetNP(occ_mesh) << endl;
+	  cout << "Number of surface elements = " << Ng_GetNSE(occ_mesh) << endl;
+   }
+
+   cout << "Creating Volume Mesh....." << endl;
+   
+   ng_res = Ng_GenerateVolumeMesh(occ_mesh, &mp);
+   
+   cout << "Volume Mesh successfully created....." << endl;
+   cout << "Number of points = " << Ng_GetNP(occ_mesh) << endl;
+   cout << "Number of volume elements = " << Ng_GetNE(occ_mesh) << endl;
+   
+   cout << "Saving Mesh as VOL file....." << endl;
+   Ng_SaveMesh(occ_mesh,"test_occ.vol");
+      
+   return 0;
+}
+