-//================================================================================
-/*!
- * \brief Calculate normal of a mesh face
- */
-//================================================================================
-
-bool SMESH_Algo::FaceNormal(const SMDS_MeshElement* F, gp_XYZ& normal, bool normalized)
-{
- if ( !F || F->GetType() != SMDSAbs_Face )
- return false;
-
- normal.SetCoord(0,0,0);
- int nbNodes = F->IsQuadratic() ? F->NbNodes()/2 : F->NbNodes();
- for ( int i = 0; i < nbNodes-2; ++i )
- {
- gp_XYZ p[3];
- for ( int n = 0; n < 3; ++n )
- {
- const SMDS_MeshNode* node = F->GetNode( i + n );
- p[n].SetCoord( node->X(), node->Y(), node->Z() );
- }
- normal += ( p[2] - p[1] ) ^ ( p[0] - p[1] );
- }
- double size2 = normal.SquareModulus();
- bool ok = ( size2 > numeric_limits<double>::min() * numeric_limits<double>::min());
- if ( normalized && ok )
- normal /= sqrt( size2 );
-
- return ok;
-}
-
-//================================================================================
-/*!
- * \brief Find out elements orientation on a geometrical face
- * \param theFace - The face correctly oriented in the shape being meshed
- * \param theMeshDS - The mesh data structure
- * \retval bool - true if the face normal and the normal of first element
- * in the correspoding submesh point in different directions
- */
-//================================================================================
-
-bool SMESH_Algo::IsReversedSubMesh (const TopoDS_Face& theFace,
- SMESHDS_Mesh* theMeshDS)
-{
- if ( theFace.IsNull() || !theMeshDS )
- return false;
-
- // find out orientation of a meshed face
- int faceID = theMeshDS->ShapeToIndex( theFace );
- TopoDS_Shape aMeshedFace = theMeshDS->IndexToShape( faceID );
- bool isReversed = ( theFace.Orientation() != aMeshedFace.Orientation() );
-
- const SMESHDS_SubMesh * aSubMeshDSFace = theMeshDS->MeshElements( faceID );
- if ( !aSubMeshDSFace )
- return isReversed;
-
- // find element with node located on face and get its normal
- const SMDS_FacePosition* facePos = 0;
- int vertexID = 0;
- gp_Pnt nPnt[3];
- gp_Vec Ne;
- bool normalOK = false;
- SMDS_ElemIteratorPtr iteratorElem = aSubMeshDSFace->GetElements();
- while ( iteratorElem->more() ) // loop on elements on theFace
- {
- const SMDS_MeshElement* elem = iteratorElem->next();
- if ( elem && elem->NbNodes() > 2 ) {
- SMDS_ElemIteratorPtr nodesIt = elem->nodesIterator();
- const SMDS_FacePosition* fPos = 0;
- int i = 0, vID = 0;
- while ( nodesIt->more() ) { // loop on nodes
- const SMDS_MeshNode* node
- = static_cast<const SMDS_MeshNode *>(nodesIt->next());
- if ( i == 3 ) i = 2;
- nPnt[ i++ ].SetCoord( node->X(), node->Y(), node->Z() );
- // check position
- const SMDS_PositionPtr& pos = node->GetPosition();
- if ( !pos ) continue;
- if ( pos->GetTypeOfPosition() == SMDS_TOP_FACE ) {
- fPos = dynamic_cast< const SMDS_FacePosition* >( pos );
- }
- else if ( pos->GetTypeOfPosition() == SMDS_TOP_VERTEX ) {
- vID = node->getshapeId();
- }
- }
- if ( fPos || ( !normalOK && vID )) {
- // compute normal
- gp_Vec v01( nPnt[0], nPnt[1] ), v02( nPnt[0], nPnt[2] );
- if ( v01.SquareMagnitude() > RealSmall() &&
- v02.SquareMagnitude() > RealSmall() )
- {
- Ne = v01 ^ v02;
- normalOK = ( Ne.SquareMagnitude() > RealSmall() );
- }
- // we need position on theFace or at least on vertex
- if ( normalOK ) {
- vertexID = vID;
- if ((facePos = fPos))
- break;
- }
- }
- }
- }
- if ( !normalOK )
- return isReversed;
-
- // node position on face
- double u,v;
- if ( facePos ) {
- u = facePos->GetUParameter();
- v = facePos->GetVParameter();
- }
- else if ( vertexID ) {
- TopoDS_Shape V = theMeshDS->IndexToShape( vertexID );
- if ( V.IsNull() || V.ShapeType() != TopAbs_VERTEX )
- return isReversed;
- gp_Pnt2d uv = BRep_Tool::Parameters( TopoDS::Vertex( V ), theFace );
- u = uv.X();
- v = uv.Y();
- }
- else
- {
- return isReversed;
- }
-
- // face normal at node position
- TopLoc_Location loc;
- Handle(Geom_Surface) surf = BRep_Tool::Surface( theFace, loc );
- // if ( surf.IsNull() || surf->Continuity() < GeomAbs_C1 )
- // some surfaces not detected as GeomAbs_C1 are nevertheless correct for meshing
- if ( surf.IsNull() || surf->Continuity() < GeomAbs_C0 )
- {
- if (!surf.IsNull())
- MESSAGE("surf->Continuity() < GeomAbs_C1 " << (surf->Continuity() < GeomAbs_C1));
- return isReversed;
- }
- gp_Vec d1u, d1v;
- surf->D1( u, v, nPnt[0], d1u, d1v );
- gp_Vec Nf = (d1u ^ d1v).Transformed( loc );
-
- if ( theFace.Orientation() == TopAbs_REVERSED )
- Nf.Reverse();
-
- return Ne * Nf < 0.;
-}
-