added triFace::reverseFace() for symmetry with face class

src/OpenFOAM/meshes/meshShapes/triFace/triFace.H

@@ -124,6 +124,9 @@ public:
             //- Return vector normal
             inline vector normal(const pointField&) const;
 
+            //- Return face with reverse direction
+            inline triFace reverseFace() const;
+
             //- Return swept-volume
             inline scalar sweptVol
             (

src/OpenFOAM/meshes/meshShapes/triFace/triFaceI.H

@@ -78,9 +78,9 @@ inline Foam::triFace::triFace
 }
 
 
-inline Foam::triFace::triFace(const UList<label>& l)
+inline Foam::triFace::triFace(const UList<label>& lst)
 :
-    FixedList<label, 3>(l)
+    FixedList<label, 3>(lst)
 {}
 
 
@@ -96,7 +96,7 @@ inline Foam::label Foam::triFace::collapse()
 {
     // we cannot resize a FixedList, so mark duplicates with '-1'
     // (the lower vertex is retained)
-    // catch any '-1' - ie, if called twice
+    // catch any '-1' (eg, if called twice)
 
     label n = 3;
     if (operator[](0) == operator[](1) || operator[](1) == -1)
@@ -154,13 +154,13 @@ inline Foam::edgeList Foam::triFace::edges() const
     edgeList e(3);
 
     e[0].start() = operator[](0);
-    e[0].end() = operator[](1);
+    e[0].end()   = operator[](1);
 
     e[1].start() = operator[](1);
-    e[1].end() = operator[](2);
+    e[1].end()   = operator[](2);
 
     e[2].start() = operator[](2);
-    e[2].end() = operator[](0);
+    e[2].end()   = operator[](0);
 
     return e;
 }
@@ -213,7 +213,7 @@ inline Foam::scalar Foam::triFace::mag(const pointField& points) const
     return ::Foam::mag(normal(points));
 }
 
-
+// could also delegate to triPointRef(...).normal()
 inline Foam::vector Foam::triFace::normal(const pointField& points) const
 {
     return 0.5*
@@ -224,6 +224,13 @@ inline Foam::vector Foam::triFace::normal(const pointField& points) const
 }
 
 
+inline Foam::triFace Foam::triFace::reverseFace() const
+{
+    // The starting points of the original and reverse face are identical.
+    return triFace(operator[](0), operator[](2), operator[](1));
+}
+
+
 inline Foam::scalar Foam::triFace::sweptVol
 (
     const pointField& opts,