ENH: plane sampling: make triangulation optional

applications/utilities/postProcessing/sampling/sample/sampleDict

@@ -165,6 +165,10 @@ surfaces
 
         //- Optional: restrict to a particular zone
         // zone        zone1;
+
+        //- Optional: do not triangulate (only for surfaceFormats that support
+        //            polygons)
+        //triangulate     false;
     }
 
     interpolatedPlane

src/sampling/sampledSurface/sampledPlane/sampledPlane.C

@@ -45,12 +45,14 @@ Foam::sampledPlane::sampledPlane
     const word& name,
     const polyMesh& mesh,
     const plane& planeDesc,
-    const keyType& zoneKey
+    const keyType& zoneKey,
+    const bool triangulate
 )
 :
     sampledSurface(name, mesh),
     cuttingPlane(planeDesc),
     zoneKey_(zoneKey),
+    triangulate_(triangulate),
     needsUpdate_(true)
 {
     if (debug && zoneKey_.size() && mesh.cellZones().findIndex(zoneKey_) < 0)
@@ -71,6 +73,7 @@ Foam::sampledPlane::sampledPlane
     sampledSurface(name, mesh, dict),
     cuttingPlane(plane(dict.lookup("basePoint"), dict.lookup("normalVector"))),
     zoneKey_(keyType::null),
+    triangulate_(dict.lookupOrDefault("triangulate", true)),
     needsUpdate_(true)
 {
     // make plane relative to the coordinateSystem (Cartesian)
@@ -138,11 +141,11 @@ bool Foam::sampledPlane::update()
 
     if (selectedCells.empty())
     {
-        reCut(mesh(), true);    // always triangulate. Note:Make option?
+        reCut(mesh(), triangulate_);
     }
     else
     {
-        reCut(mesh(), true, selectedCells);
+        reCut(mesh(), triangulate_, selectedCells);
     }
 
     if (debug)
@@ -250,6 +253,7 @@ void Foam::sampledPlane::print(Ostream& os) const
     os  << "sampledPlane: " << name() << " :"
         << "  base:" << refPoint()
         << "  normal:" << normal()
+        << "  triangulate:" << triangulate_
         << "  faces:" << faces().size()
         << "  points:" << points().size();
 }

src/sampling/sampledSurface/sampledPlane/sampledPlane.H

@@ -25,7 +25,7 @@ Class
     Foam::sampledPlane
 
 Description
-    A sampledSurface defined by a cuttingPlane. Always triangulated.
+    A sampledSurface defined by a cuttingPlane. Triangulated by default.
 
 Note
     Does not actually cut until update() called.
@@ -60,6 +60,9 @@ class sampledPlane
         //- If restricted to zones, name of this zone or a regular expression
         keyType zoneKey_;
 
+        //- Triangulated faces or keep faces as is
+        const bool triangulate_;
+
         //- Track if the surface needs an update
         mutable bool needsUpdate_;
 
@@ -92,7 +95,8 @@ public:
             const word& name,
             const polyMesh& mesh,
             const plane& planeDesc,
-            const keyType& zoneKey = word::null
+            const keyType& zoneKey = word::null,
+            const bool triangulate = true
         );
 
         //- Construct from dictionary