iso surface correction

src/sampling/sampledSurface/isoSurface/isoSurface.C

@@ -85,9 +85,74 @@ bool Foam::isoSurface::isEdgeOfFaceCut
 }
 
 
+// Get neighbour value and position.
+void Foam::isoSurface::getNeighbour
+(
+    const labelList& boundaryRegion,
+    const volScalarField& cVals,
+    const label cellI,
+    const label faceI,
+    scalar& nbrValue,
+    point& nbrPoint
+) const
+{
+    const labelList& own = mesh_.faceOwner();
+    const labelList& nei = mesh_.faceNeighbour();
+    const surfaceScalarField& weights = mesh_.weights();
+
+    if (mesh_.isInternalFace(faceI))
+    {
+        label nbr = (own[faceI] == cellI ? nei[faceI] : own[faceI]);
+        nbrValue = cVals[nbr];
+        nbrPoint = mesh_.cellCentres()[nbr];
+    }
+    else
+    {
+        label bFaceI = faceI-mesh_.nInternalFaces();
+        label patchI = boundaryRegion[bFaceI];
+        const polyPatch& pp = mesh_.boundaryMesh()[patchI];
+        label patchFaceI = faceI-pp.start();
+
+        if (isA<emptyPolyPatch>(pp))
+        {
+            // Assume zero gradient
+            nbrValue = cVals[own[faceI]];
+            nbrPoint = mesh_.faceCentres()[faceI];
+        }
+        else if (pp.coupled())
+        {
+            if (!refCast<const coupledPolyPatch>(pp).separated())
+            {
+                // Behave as internal face:
+                // other side value
+                nbrValue = cVals.boundaryField()[patchI][patchFaceI];
+                // other side cell centre
+                nbrPoint = mesh_.C().boundaryField()[patchI][patchFaceI];
+            }
+            else
+            {
+                // Do some interpolation for now
+                const scalarField& w = weights.boundaryField()[patchI];
+
+                nbrPoint = mesh_.faceCentres()[faceI];
+                nbrValue =
+                    (1-w[patchFaceI])*cVals[own[faceI]]
+                  + w[patchFaceI]*cVals.boundaryField()[patchI][patchFaceI];
+            }
+        }
+        else
+        {
+            nbrValue = cVals.boundaryField()[patchI][patchFaceI];
+            nbrPoint = mesh_.faceCentres()[faceI];
+        }
+    }
+}
+
+
 // Determine for every face/cell whether it (possibly) generates triangles.
 void Foam::isoSurface::calcCutTypes
 (
+    const labelList& boundaryRegion,
     const volScalarField& cVals,
     const scalarField& pVals
 )
@@ -103,7 +168,20 @@ void Foam::isoSurface::calcCutTypes
     {
         // CC edge.
         bool ownLower = (cVals[own[faceI]] < iso_);
-        bool neiLower = (cVals[nei[faceI]] < iso_);
+
+        scalar nbrValue;
+        point nbrPoint;
+        getNeighbour
+        (
+            boundaryRegion,
+            cVals,
+            own[faceI],
+            faceI,
+            nbrValue,
+            nbrPoint
+        );
+
+        bool neiLower = (nbrValue < iso_);
 
         if (ownLower != neiLower)
         {
@@ -129,15 +207,29 @@ void Foam::isoSurface::calcCutTypes
 
         if (isA<emptyPolyPatch>(pp))
         {
-            // Assume zero gradient so owner and neighbour/boundary value equal
+            // Still needs special treatment?
 
             forAll(pp, i)
             {
                 bool ownLower = (cVals[own[faceI]] < iso_);
 
+                scalar nbrValue;
+                point nbrPoint;
+                getNeighbour
+                (
+                    boundaryRegion,
+                    cVals,
+                    own[faceI],
+                    faceI,
+                    nbrValue,
+                    nbrPoint
+                );
+
+                bool neiLower = (nbrValue < iso_);
+
                 const face f = mesh_.faces()[faceI];
 
-                if (isEdgeOfFaceCut(pVals, f, ownLower, ownLower))
+                if (isEdgeOfFaceCut(pVals, f, ownLower, neiLower))
                 {
                     faceCutType_[faceI] = CUT;
                 }
@@ -150,7 +242,20 @@ void Foam::isoSurface::calcCutTypes
             forAll(pp, i)
             {
                 bool ownLower = (cVals[own[faceI]] < iso_);
-                bool neiLower = (cVals.boundaryField()[patchI][i] < iso_);
+
+                scalar nbrValue;
+                point nbrPoint;
+                getNeighbour
+                (
+                    boundaryRegion,
+                    cVals,
+                    own[faceI],
+                    faceI,
+                    nbrValue,
+                    nbrPoint
+                );
+
+                bool neiLower = (nbrValue < iso_);
 
                 if (ownLower != neiLower)
                 {
@@ -166,6 +271,7 @@ void Foam::isoSurface::calcCutTypes
                         faceCutType_[faceI] = CUT;
                     }
                 }
+
                 faceI++;
             }
         }
@@ -331,70 +437,6 @@ Foam::pointIndexHit Foam::isoSurface::collapseSurface
 }
 
 
-// Get neighbour value and position.
-void Foam::isoSurface::getNeighbour
-(
-    const labelList& boundaryRegion,
-    const volScalarField& cVals,
-    const label cellI,
-    const label faceI,
-    scalar& nbrValue,
-    point& nbrPoint
-) const
-{
-    const labelList& own = mesh_.faceOwner();
-    const labelList& nei = mesh_.faceNeighbour();
-    const surfaceScalarField& weights = mesh_.weights();
-
-    if (mesh_.isInternalFace(faceI))
-    {
-        label nbr = (own[faceI] == cellI ? nei[faceI] : own[faceI]);
-        nbrValue = cVals[nbr];
-        nbrPoint = mesh_.cellCentres()[nbr];
-    }
-    else
-    {
-        label bFaceI = faceI-mesh_.nInternalFaces();
-        label patchI = boundaryRegion[bFaceI];
-        const polyPatch& pp = mesh_.boundaryMesh()[patchI];
-        label patchFaceI = faceI-pp.start();
-
-        if (isA<emptyPolyPatch>(pp))
-        {
-            // Assume zero gradient
-            nbrValue = cVals[own[faceI]];
-            nbrPoint = mesh_.faceCentres()[faceI];
-        }
-        else if (pp.coupled())
-        {
-            if (!refCast<const coupledPolyPatch>(pp).separated())
-            {
-                // Behave as internal face:
-                // other side value
-                nbrValue = cVals.boundaryField()[patchI][patchFaceI];
-                // other side cell centre
-                nbrPoint = mesh_.C().boundaryField()[patchI][patchFaceI];
-            }
-            else
-            {
-                // Do some interpolation for now
-                const scalarField& w = weights.boundaryField()[patchI];
-
-                nbrPoint = mesh_.faceCentres()[faceI];
-                nbrValue =
-                    (1-w[patchFaceI])*cVals[own[faceI]]
-                  + w[patchFaceI]*cVals.boundaryField()[patchI][patchFaceI];
-            }
-        }
-        else
-        {
-            nbrValue = cVals.boundaryField()[patchI][patchFaceI];
-            nbrPoint = mesh_.faceCentres()[faceI];
-        }
-    }
-}
-
-
 // Determine per cell centre whether all the intersections get collapsed
 // to a single point
 void Foam::isoSurface::calcSnappedCc
@@ -618,13 +660,14 @@ void Foam::isoSurface::calcSnappedPoint
 
         forAll(pFaces, pFaceI)
         {
+            // Create points for all intersections close to point
+            // (i.e. from pyramid edges)
+
             label faceI = pFaces[pFaceI];
             const face& f = mesh_.faces()[faceI];
             label own = mesh_.faceOwner()[faceI];
 
-            // Create points for all intersections close to point
+            // Get neighbour value
-            // (i.e. from pyramid edges)
-
             scalar nbrValue;
             point nbrPoint;
             getNeighbour
@@ -843,6 +886,7 @@ Foam::triSurface Foam::isoSurface::stitchTriPoints
     }
 
 
+
     // Determine 'flat hole' situation (see RMT paper).
     // Two unconnected triangles get connected because (some of) the edges
     // separating them get collapsed. Below only checks for duplicate triangles,
@@ -870,6 +914,9 @@ Foam::triSurface Foam::isoSurface::stitchTriPoints
 
                 if (nbrTriI > triI && (tris[nbrTriI] == tri))
                 {
+                    //Pout<< "Duplicate : " << triI << " verts:" << tri
+                    //    << " to " << nbrTriI << " verts:" << tris[nbrTriI]
+                    //    << endl;
                     dupTriI = nbrTriI;
                     break;
                 }
@@ -1526,8 +1573,14 @@ Foam::isoSurface::isoSurface
 {
     if (debug)
     {
-        Pout<< "isoSurface     :" << nl
+        Pout<< "isoSurface:" << nl
             << "    isoField      : " << cVals.name() << nl
+            << "    cell min/max  : "
+            << min(cVals.internalField()) << " / "
+            << max(cVals.internalField()) << nl
+            << "    point min/max : "
+            << min(pVals) << " / "
+            << max(pVals) << nl
             << "    isoValue      : " << iso << nl
             << "    regularise    : " << regularise << nl
             << "    mergeTol      : " << mergeTol << nl
@@ -1556,15 +1609,7 @@ Foam::isoSurface::isoSurface
         }
     }
 
-
+    // Pre-calculate patch-per-face to avoid whichPatch call.
-    // Determine if any cut through face/cell
-    calcCutTypes(cVals, pVals);
-
-
-    // Determine if point is on boundary. Points on boundaries are never
-    // snapped. Coupled boundaries are handled explicitly so not marked here.
-    PackedBoolList isBoundaryPoint(mesh_.nPoints());
-
     labelList boundaryRegion(mesh_.nFaces()-mesh_.nInternalFaces());
 
     forAll(patches, patchI)
@@ -1578,29 +1623,11 @@ Foam::isoSurface::isoSurface
             boundaryRegion[faceI-mesh_.nInternalFaces()] = patchI;
             faceI++;
         }
+    }
 
-        // Mark all boundary points that are not physically coupled (so anything
-        // but collocated coupled patches)
-        if
-        (
-           !pp.coupled()
-        || refCast<const coupledPolyPatch>(pp).separated()
-        )
-        {
-            label faceI = pp.start();
 
-            forAll(pp, i)
+    // Determine if any cut through face/cell
-            {
+    calcCutTypes(boundaryRegion, cVals, pVals);
-                const face& f = mesh_.faces()[faceI];
-
-                forAll(f, fp)
-                {
-                    isBoundaryPoint.set(f[fp], 1);
-                }
-                faceI++;
-            }
-        }
-    }
 
 
     DynamicList<point> snappedPoints(nCutCells_);
@@ -1635,6 +1662,39 @@ Foam::isoSurface::isoSurface
 
     label nCellSnaps = snappedPoints.size();
 
+
+    // Determine if point is on boundary. Points on boundaries are never
+    // snapped. Coupled boundaries are handled explicitly so not marked here.
+    PackedBoolList isBoundaryPoint(mesh_.nPoints());
+
+    forAll(patches, patchI)
+    {
+        // Mark all boundary points that are not physically coupled (so anything
+        // but collocated coupled patches)
+        const polyPatch& pp = patches[patchI];
+
+        if
+        (
+           !pp.coupled()
+        || refCast<const coupledPolyPatch>(pp).separated()
+        )
+        {
+            label faceI = pp.start();
+
+            forAll(pp, i)
+            {
+                const face& f = mesh_.faces()[faceI];
+
+                forAll(f, fp)
+                {
+                    isBoundaryPoint.set(f[fp], 1);
+                }
+                faceI++;
+            }
+        }
+    }
+
+
     // Per point -1 or a point inside snappedPoints.
     labelList snappedPoint;
     if (regularise)
@@ -1727,7 +1787,8 @@ Foam::isoSurface::isoSurface
     if (debug)
     {
         Pout<< "isoSurface : generated " << triMeshCells.size()
-            << " unmerged triangles." << endl;
+            << " unmerged triangles from " << triPoints.size()
+            << " unmerged points." << endl;
     }
 
 

src/sampling/sampledSurface/isoSurface/isoSurface.H

@@ -135,9 +135,20 @@ class isoSurface
             const bool neiLower
         ) const;
 
+        void getNeighbour
+        (
+            const labelList& boundaryRegion,
+            const volScalarField& cVals,
+            const label cellI,
+            const label faceI,
+            scalar& nbrValue,
+            point& nbrPoint
+        ) const;
+
         //- Set faceCutType,cellCutType.
         void calcCutTypes
         (
+            const labelList& boundaryRegion,
             const volScalarField& cVals,
             const scalarField& pVals
         );
@@ -156,16 +167,6 @@ class isoSurface
             DynamicList<labelledTri, 64>& localTris
         );
 
-        void getNeighbour
-        (
-            const labelList& boundaryRegion,
-            const volScalarField& cVals,
-            const label cellI,
-            const label faceI,
-            scalar& nbrValue,
-            point& nbrPoint
-        ) const;
-
         //- Determine per cc whether all near cuts can be snapped to single
         //  point.
         void calcSnappedCc
@@ -193,37 +194,39 @@ class isoSurface
         template<class Type>
         Type generatePoint
         (
-            const DynamicList<Type>& snappedPoints,
-
             const scalar s0,
             const Type& p0,
-            const label p0Index,
+            const bool hasSnap0,
+            const Type& snapP0,
 
             const scalar s1,
             const Type& p1,
-            const label p1Index
+            const bool hasSnap1,
+            const Type& snapP1
         ) const;
 
         template<class Type>
         void generateTriPoints
         (
-            const DynamicList<Type>& snapped,
-
             const scalar s0,
             const Type& p0,
-            const label p0Index,
+            const bool hasSnap0,
+            const Type& snapP0,
 
             const scalar s1,
             const Type& p1,
-            const label p1Index,
+            const bool hasSnap1,
+            const Type& snapP1,
 
             const scalar s2,
             const Type& p2,
-            const label p2Index,
+            const bool hasSnap2,
+            const Type& snapP2,
 
             const scalar s3,
             const Type& p3,
-            const label p3Index,
+            const bool hasSnap3,
+            const Type& snapP3,
 
             DynamicList<Type>& points
         ) const;
@@ -244,7 +247,8 @@ class isoSurface
 
             const scalar neiVal,
             const Type& neiPt,
-            const label neiSnap,
+            const bool hasNeiSnap,
+            const Type& neiSnapPt,
 
             DynamicList<Type>& triPoints,
             DynamicList<label>& triMeshCells

src/sampling/sampledSurface/isoSurface/isoSurfaceTemplates.C

@@ -33,15 +33,15 @@ License
 template<class Type>
 Type Foam::isoSurface::generatePoint
 (
-    const DynamicList<Type>& snappedPoints,
-
     const scalar s0,
     const Type& p0,
-    const label p0Index,
+    const bool hasSnap0,
+    const Type& snapP0,
 
     const scalar s1,
     const Type& p1,
-    const label p1Index
+    const bool hasSnap1,
+    const Type& snapP1
 ) const
 {
     scalar d = s1-s0;
@@ -50,13 +50,13 @@ Type Foam::isoSurface::generatePoint
     {
         scalar s = (iso_-s0)/d;
 
-        if (s >= 0.5 && s <= 1 && p1Index != -1)
+        if (hasSnap1 && s >= 0.5 && s <= 1)
         {
-            return snappedPoints[p1Index];
+            return snapP1;
         }
-        else if (s >= 0.0 && s <= 0.5 && p0Index != -1)
+        else if (hasSnap0 && s >= 0.0 && s <= 0.5)
         {
-            return snappedPoints[p0Index];
+            return snapP0;
         }
         else
         {
@@ -75,23 +75,25 @@ Type Foam::isoSurface::generatePoint
 template<class Type>
 void Foam::isoSurface::generateTriPoints
 (
-    const DynamicList<Type>& snapped,
-
     const scalar s0,
     const Type& p0,
-    const label p0Index,
+    const bool hasSnap0,
+    const Type& snapP0,
 
     const scalar s1,
     const Type& p1,
-    const label p1Index,
+    const bool hasSnap1,
+    const Type& snapP1,
 
     const scalar s2,
     const Type& p2,
-    const label p2Index,
+    const bool hasSnap2,
+    const Type& snapP2,
 
     const scalar s3,
     const Type& p3,
-    const label p3Index,
+    const bool hasSnap3,
+    const Type& snapP3,
 
     DynamicList<Type>& points
 ) const
@@ -123,29 +125,55 @@ void Foam::isoSurface::generateTriPoints
 
         case 0x0E:
         case 0x01:
-            points.append(generatePoint(snapped,s0,p0,p0Index,s1,p1,p1Index));
+            points.append
-            points.append(generatePoint(snapped,s0,p0,p0Index,s2,p2,p2Index));
+            (
-            points.append(generatePoint(snapped,s0,p0,p0Index,s3,p3,p3Index));
+                generatePoint(s0,p0,hasSnap0,snapP0,s1,p1,hasSnap1,snapP1)
+            );
+            points.append
+            (
+                generatePoint(s0,p0,hasSnap0,snapP0,s2,p2,hasSnap2,snapP2)
+            );
+            points.append
+            (
+                generatePoint(s0,p0,hasSnap0,snapP0,s3,p3,hasSnap3,snapP3)
+            );
         break;
 
         case 0x0D:
         case 0x02:
-            points.append(generatePoint(snapped,s1,p1,p1Index,s0,p0,p0Index));
+            points.append
-            points.append(generatePoint(snapped,s1,p1,p1Index,s3,p3,p3Index));
+            (
-            points.append(generatePoint(snapped,s1,p1,p1Index,s2,p2,p2Index));
+                generatePoint(s1,p1,hasSnap1,snapP1,s0,p0,hasSnap0,snapP0)
+            );
+            points.append
+            (
+                generatePoint(s1,p1,hasSnap1,snapP1,s3,p3,hasSnap3,snapP3)
+            );
+            points.append
+            (
+                generatePoint(s1,p1,hasSnap1,snapP1,s2,p2,hasSnap2,snapP2)
+            );
         break;
 
         case 0x0C:
         case 0x03:
         {
-            Type tp1 = generatePoint(snapped,s0,p0,p0Index,s2,p2,p2Index);
+            Type tp1 =
-            Type tp2 = generatePoint(snapped,s1,p1,p1Index,s3,p3,p3Index);
+                generatePoint(s0,p0,hasSnap0,snapP0,s2,p2,hasSnap2,snapP2);
+            Type tp2 =
+                generatePoint(s1,p1,hasSnap1,snapP1,s3,p3,hasSnap3,snapP3);
 
-            points.append(generatePoint(snapped,s0,p0,p0Index,s3,p3,p3Index));
+            points.append
+            (
+                generatePoint(s0,p0,hasSnap0,snapP0,s3,p3,hasSnap3,snapP3)
+            );
             points.append(tp1);
             points.append(tp2);
             points.append(tp2);
-            points.append(generatePoint(snapped,s1,p1,p1Index,s2,p2,p2Index));
+            points.append
+            (
+                generatePoint(s1,p1,hasSnap1,snapP1,s2,p2,hasSnap2,snapP2)
+            );
             points.append(tp1);
         }
         break;
@@ -153,23 +181,40 @@ void Foam::isoSurface::generateTriPoints
         case 0x0B:
         case 0x04:
         {
-            points.append(generatePoint(snapped,s2,p2,p2Index,s0,p0,p0Index));
+            points.append
-            points.append(generatePoint(snapped,s2,p2,p2Index,s1,p1,p1Index));
+            (
-            points.append(generatePoint(snapped,s2,p2,p2Index,s3,p3,p3Index));
+                generatePoint(s2,p2,hasSnap2,snapP2,s0,p0,hasSnap0,snapP0)
+            );
+            points.append
+            (
+                generatePoint(s2,p2,hasSnap2,snapP2,s1,p1,hasSnap1,snapP1)
+            );
+            points.append
+            (
+                generatePoint(s2,p2,hasSnap2,snapP2,s3,p3,hasSnap3,snapP3)
+            );
         }
         break;
 
         case 0x0A:
         case 0x05:
         {
-            Type tp0 = generatePoint(snapped,s0,p0,p0Index,s1,p1,p1Index);
+            Type tp0 =
-            Type tp1 = generatePoint(snapped,s2,p2,p2Index,s3,p3,p3Index);
+                generatePoint(s0,p0,hasSnap0,snapP0,s1,p1,hasSnap1,snapP1);
+            Type tp1 =
+                generatePoint(s2,p2,hasSnap2,snapP2,s3,p3,hasSnap3,snapP3);
 
             points.append(tp0);
             points.append(tp1);
-            points.append(generatePoint(snapped,s0,p0,p0Index,s3,p3,p3Index));
+            points.append
+            (
+                generatePoint(s0,p0,hasSnap0,snapP0,s3,p3,hasSnap3,snapP3)
+            );
             points.append(tp0);
-            points.append(generatePoint(snapped,s1,p1,p1Index,s2,p2,p2Index));
+            points.append
+            (
+                generatePoint(s1,p1,hasSnap1,snapP1,s2,p2,hasSnap2,snapP2)
+            );
             points.append(tp1);
         }
         break;
@@ -177,23 +222,40 @@ void Foam::isoSurface::generateTriPoints
         case 0x09:
         case 0x06:
         {
-            Type tp0 = generatePoint(snapped,s0,p0,p0Index,s1,p1,p1Index);
+            Type tp0 =
-            Type tp1 = generatePoint(snapped,s2,p2,p2Index,s3,p3,p3Index);
+                generatePoint(s0,p0,hasSnap0,snapP0,s1,p1,hasSnap1,snapP1);
+            Type tp1 =
+                generatePoint(s2,p2,hasSnap2,snapP2,s3,p3,hasSnap3,snapP3);
 
             points.append(tp0);
-            points.append(generatePoint(snapped,s1,p1,p1Index,s3,p3,p3Index));
+            points.append
+            (
+                generatePoint(s1,p1,hasSnap1,snapP1,s3,p3,hasSnap3,snapP3)
+            );
             points.append(tp1);
             points.append(tp0);
-            points.append(generatePoint(snapped,s0,p0,p0Index,s2,p2,p2Index));
+            points.append
+            (
+                generatePoint(s0,p0,hasSnap0,snapP0,s2,p2,hasSnap2,snapP2)
+            );
             points.append(tp1);
         }
         break;
 
         case 0x07:
         case 0x08:
-            points.append(generatePoint(snapped,s3,p3,p3Index,s0,p0,p0Index));
+            points.append
-            points.append(generatePoint(snapped,s3,p3,p3Index,s2,p2,p2Index));
+            (
-            points.append(generatePoint(snapped,s3,p3,p3Index,s1,p1,p1Index));
+                generatePoint(s3,p3,hasSnap3,snapP3,s0,p0,hasSnap0,snapP0)
+            );
+            points.append
+            (
+                generatePoint(s3,p3,hasSnap3,snapP3,s2,p2,hasSnap2,snapP2)
+            );
+            points.append
+            (
+                generatePoint(s3,p3,hasSnap3,snapP3,s1,p1,hasSnap1,snapP1)
+            );
         break;
     }
 }
@@ -215,7 +277,8 @@ Foam::label Foam::isoSurface::generateFaceTriPoints
 
     const scalar neiVal,
     const Type& neiPt,
-    const label neiSnap,
+    const bool hasNeiSnap,
+    const Type& neiSnapPt,
 
     DynamicList<Type>& triPoints,
     DynamicList<label>& triMeshCells
@@ -234,23 +297,37 @@ Foam::label Foam::isoSurface::generateFaceTriPoints
 
         generateTriPoints
         (
-            snappedPoints,
-
             pVals[pointI],
             pCoords[pointI],
-            snappedPoint[pointI],
+            snappedPoint[pointI] != -1,
+            (
+                snappedPoint[pointI] != -1
+              ? snappedPoints[snappedPoint[pointI]]
+              : pTraits<Type>::zero
+            ),
 
             pVals[nextPointI],
             pCoords[nextPointI],
-            snappedPoint[nextPointI],
+            snappedPoint[nextPointI] != -1,
+            (
+                snappedPoint[nextPointI] != -1
+              ? snappedPoints[snappedPoint[nextPointI]]
+              : pTraits<Type>::zero
+            ),
 
             cVals[own],
             cCoords[own],
-            snappedCc[own],
+            snappedCc[own] != -1,
+            (
+                snappedCc[own] != -1
+              ? snappedPoints[snappedCc[own]]
+              : pTraits<Type>::zero
+            ),
 
             neiVal,
             neiPt,
-            neiSnap,
+            hasNeiSnap,
+            neiSnapPt,
 
             triPoints
         );
@@ -311,25 +388,6 @@ void Foam::isoSurface::generateTriPoints
             << abort(FatalError);
     }
 
-    // Determine neighbouring snap status
-    labelList neiSnappedCc(mesh_.nFaces()-mesh_.nInternalFaces(), -1);
-    forAll(patches, patchI)
-    {
-        const polyPatch& pp = patches[patchI];
-
-        if (pp.coupled())
-        {
-            label faceI = pp.start();
-            forAll(pp, i)
-            {
-                neiSnappedCc[faceI-mesh_.nInternalFaces()] =
-                    snappedCc[own[faceI]];
-                faceI++;
-            }
-        }
-    }
-    syncTools::swapBoundaryFaceList(mesh_, neiSnappedCc, false);
-
 
 
     // Generate triangle points
@@ -356,7 +414,12 @@ void Foam::isoSurface::generateTriPoints
 
                 cVals[nei[faceI]],
                 cCoords[nei[faceI]],
-                snappedCc[nei[faceI]],
+                snappedCc[nei[faceI]] != -1,
+                (
+                    snappedCc[nei[faceI]] != -1
+                  ? snappedPoints[snappedCc[nei[faceI]]]
+                  : pTraits<Type>::zero
+                ),
 
                 triPoints,
                 triMeshCells
@@ -365,6 +428,34 @@ void Foam::isoSurface::generateTriPoints
     }
 
 
+    // Determine neighbouring snap status
+    boolList neiSnapped(mesh_.nFaces()-mesh_.nInternalFaces(), false);
+    List<Type> neiSnappedPoint(neiSnapped.size(), pTraits<Type>::zero);
+    forAll(patches, patchI)
+    {
+        const polyPatch& pp = patches[patchI];
+
+        if (pp.coupled())
+        {
+            label faceI = pp.start();
+            forAll(pp, i)
+            {
+                label bFaceI = faceI-mesh_.nInternalFaces();
+                label snappedIndex = snappedCc[own[faceI]];
+
+                if (snappedIndex != -1)
+                {
+                    neiSnapped[bFaceI] = true;
+                    neiSnappedPoint[bFaceI] = snappedPoints[snappedIndex];
+                }
+                faceI++;
+            }
+        }
+    }
+    syncTools::swapBoundaryFaceList(mesh_, neiSnapped, false);
+    syncTools::swapBoundaryFaceList(mesh_, neiSnappedPoint, false);
+
+
     forAll(patches, patchI)
     {
         const polyPatch& pp = patches[patchI];
@@ -372,9 +463,10 @@ void Foam::isoSurface::generateTriPoints
         if
         (
             isA<processorPolyPatch>(pp)
-         && refCast<const processorPolyPatch>(pp).owner()
          && !refCast<const processorPolyPatch>(pp).separated()
         )
+        {
+            //if (refCast<const processorPolyPatch>(pp).owner())
             {
                 label faceI = pp.start();
 
@@ -382,6 +474,18 @@ void Foam::isoSurface::generateTriPoints
                 {
                     if (faceCutType_[faceI] != NOTCUT)
                     {
+                        label bFaceI = faceI-mesh_.nInternalFaces();
+                        if
+                        (
+                            neiSnapped[bFaceI]
+                         && (neiSnappedPoint[bFaceI]==pTraits<Type>::zero)
+                        )
+                        {
+                            FatalErrorIn("isoSurface::generateTriPoints(..)")
+                                << "problem:" << abort(FatalError);
+                        }
+
+
                         generateFaceTriPoints
                         (
                             cVals,
@@ -397,7 +501,8 @@ void Foam::isoSurface::generateTriPoints
 
                             cVals.boundaryField()[patchI][i],
                             cCoords.boundaryField()[patchI][i],
-                        neiSnappedCc[faceI-mesh_.nInternalFaces()],
+                            neiSnapped[faceI-mesh_.nInternalFaces()],
+                            neiSnappedPoint[faceI-mesh_.nInternalFaces()],
 
                             triPoints,
                             triMeshCells
@@ -406,6 +511,7 @@ void Foam::isoSurface::generateTriPoints
                     faceI++;
                 }
             }
+        }
         else if (isA<emptyPolyPatch>(pp))
         {
             // Assume zero-gradient. But what about coordinates?
@@ -430,7 +536,8 @@ void Foam::isoSurface::generateTriPoints
 
                         cVals[own[faceI]],
                         cCoords.boundaryField()[patchI][i],
-                        -1, // fc not snapped
+                        false,  // fc not snapped
+                        pTraits<Type>::zero,
 
                         triPoints,
                         triMeshCells
@@ -462,7 +569,8 @@ void Foam::isoSurface::generateTriPoints
 
                         cVals.boundaryField()[patchI][i],
                         cCoords.boundaryField()[patchI][i],
-                        -1, // fc not snapped
+                        false,  // fc not snapped
+                        pTraits<Type>::zero,
 
                         triPoints,
                         triMeshCells