ENH: creating a bounding box without points yields an inverted box

- The code create a box with a (0,0,0) point.
  The new definition is more logical and makes it very easy to grow
  the bounding box to include new points. It also simplifies much of
  the logic in the constructors.

- Use ROOTVGREAT instead of VGREAT for sizing greatBox and invertedBox.
  Avoids some overflow issues reported by Mattijs (thus GREAT has been
  used in treeBoundBox), but might still need further revision.

applications/utilities/mesh/generation/foamyMesh/conformalVoronoiMesh/backgroundMeshDecomposition/backgroundMeshDecomposition.C

@@ -720,7 +720,7 @@ void Foam::backgroundMeshDecomposition::buildPatchAndTree()
     Pstream::scatterList(allBackgroundMeshBounds_);
 
     // find global bounding box
-    globalBackgroundBounds_ = treeBoundBox::invertedBox;
+    globalBackgroundBounds_ = treeBoundBox(boundBox::invertedBox);
     forAll(allBackgroundMeshBounds_, proci)
     {
         globalBackgroundBounds_.add(allBackgroundMeshBounds_[proci]);

src/OpenFOAM/meshes/boundBox/boundBox.C

@@ -29,11 +29,17 @@ License
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
-// (min,max) = (-VGREAT,+VGREAT)
-const Foam::boundBox Foam::boundBox::greatBox(point::min, point::max);
+const Foam::boundBox Foam::boundBox::greatBox
+(
+    point::uniform(-ROOTVGREAT),
+    point::uniform(ROOTVGREAT)
+);
 
-// (min,max) = (+VGREAT,-VGREAT)
-const Foam::boundBox Foam::boundBox::invertedBox(point::max, point::min);
+const Foam::boundBox Foam::boundBox::invertedBox
+(
+    point::uniform(ROOTVGREAT),
+    point::uniform(-ROOTVGREAT)
+);
 
 const Foam::faceList Foam::boundBox::faces
 ({
@@ -47,25 +53,15 @@ const Foam::faceList Foam::boundBox::faces
 });
 
 
-// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
-void Foam::boundBox::calculate(const UList<point>& points, bool doReduce)
+Foam::boundBox::boundBox(const UList<point>& points, bool doReduce)
+:
+    min_(invertedBox.min()),
+    max_(invertedBox.max())
 {
-    if (points.empty())
-    {
-        if (doReduce && Pstream::parRun())
-        {
-            // Values that get overwritten by subsequent reduce operation
-            operator=(invertedBox);
-        }
-    }
-    else
-    {
-        operator=(invertedBox);
-        add(points);
-    }
+    add(points);
 
-    // Parallel reduction
     if (doReduce)
     {
         reduce();
@@ -73,24 +69,17 @@ void Foam::boundBox::calculate(const UList<point>& points, bool doReduce)
 }
 
 
-// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
-
-Foam::boundBox::boundBox(const UList<point>& points, bool doReduce)
-:
-    min_(Zero),
-    max_(Zero)
-{
-    calculate(points, doReduce);
-}
-
-
 Foam::boundBox::boundBox(const tmp<pointField>& tpoints, bool doReduce)
 :
-    min_(Zero),
-    max_(Zero)
+    min_(invertedBox.min()),
+    max_(invertedBox.max())
 {
-    calculate(tpoints(), doReduce);
-    tpoints.clear();
+    add(tpoints);
+
+    if (doReduce)
+    {
+        reduce();
+    }
 }
 
 
@@ -101,24 +90,11 @@ Foam::boundBox::boundBox
     bool doReduce
 )
 :
-    min_(Zero),
-    max_(Zero)
+    min_(invertedBox.min()),
+    max_(invertedBox.max())
 {
-    if (points.empty() || indices.empty())
-    {
-        if (doReduce && Pstream::parRun())
-        {
-            // Values that get overwritten by subsequent reduce operation
-            operator=(invertedBox);
-        }
-    }
-    else
-    {
-        operator=(invertedBox);
-        add(points, indices);
-    }
+    add(points, indices);
 
-    // Parallel reduction
     if (doReduce)
     {
         reduce();

src/OpenFOAM/meshes/boundBox/boundBox.H

@@ -27,6 +27,11 @@ Class
 Description
     A bounding box defined in terms of the points at its extremities.
 
+Note
+    When a bounding box is created without any points, it creates an inverted
+    bounding box. Points can be added later and the bounding box will grow to
+    include them.
+
 \*---------------------------------------------------------------------------*/
 
 #ifndef boundBox_H
@@ -63,20 +68,14 @@ class boundBox
         //- Minimum and maximum points describing the bounding box
         point min_, max_;
 
-    // Private Member Functions
-
-        //- Calculate the bounding box from the given points.
-        //  Does parallel communication (doReduce = true)
-        void calculate(const UList<point>& points, bool doReduce = true);
-
 public:
 
     // Static data members
 
-        //- A very large boundBox: min/max == -/+ VGREAT
+        //- A large boundBox: min/max == -/+ ROOTVGREAT
         static const boundBox greatBox;
 
-        //- A very large inverted boundBox: min/max == +/- VGREAT
+        //- A large inverted boundBox: min/max == +/- ROOTVGREAT
         static const boundBox invertedBox;
 
         //- Faces to point addressing, as per a 'hex' cell
@@ -85,7 +84,7 @@ public:
 
     // Constructors
 
-        //- Construct null, setting points to zero
+        //- Construct without any points - an inverted bounding box
         inline boundBox();
 
         //- Construct a bounding box containing a single initial point
@@ -134,6 +133,9 @@ public:
             //- Bounding box is inverted, contains no points.
             inline bool empty() const;
 
+            //- Clear bounding box of all points - make it an inverted box
+            inline void clear();
+
             //- Minimum describing the bounding box
             inline const point& min() const;
 

src/OpenFOAM/meshes/boundBox/boundBoxI.H

@@ -30,8 +30,8 @@ License
 
 inline Foam::boundBox::boundBox()
 :
-    min_(Zero),
-    max_(Zero)
+    min_(invertedBox.min()),
+    max_(invertedBox.max())
 {}
 
 
@@ -63,6 +63,13 @@ inline bool Foam::boundBox::empty() const
 }
 
 
+inline void Foam::boundBox::clear()
+{
+    min_ = invertedBox.min();
+    max_ = invertedBox.max();
+}
+
+
 inline const Foam::point& Foam::boundBox::min() const
 {
     return min_;

src/OpenFOAM/meshes/boundBox/boundBoxTemplates.C

@@ -36,25 +36,11 @@ Foam::boundBox::boundBox
     bool doReduce
 )
 :
-    min_(Zero),
-    max_(Zero)
+    min_(invertedBox.min()),
+    max_(invertedBox.max())
 {
-    // a FixedList is never empty
-    if (points.empty())
-    {
-        if (doReduce && Pstream::parRun())
-        {
-            // Values that get overwritten by subsequent reduce operation
-            operator=(invertedBox);
-        }
-    }
-    else
-    {
-        operator=(invertedBox);
-        add(points, indices);
-    }
+    add(points, indices);
 
-    // Parallel reduction
     if (doReduce)
     {
         reduce();

src/OpenFOAM/meshes/treeBoundBox/treeBoundBox.C

@@ -27,18 +27,6 @@ License
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
-const Foam::treeBoundBox Foam::treeBoundBox::greatBox
-(
-    point::uniform(-GREAT),
-    point::uniform(GREAT)
-);
-
-const Foam::treeBoundBox Foam::treeBoundBox::invertedBox
-(
-    point::uniform(GREAT),
-    point::uniform(-GREAT)
-);
-
 const Foam::faceList Foam::treeBoundBox::faces
 ({
     face{0, 4, 6, 2}, // left

src/OpenFOAM/meshes/treeBoundBox/treeBoundBox.H

@@ -46,6 +46,11 @@ Description
 
     For the front plane add 4 to the point labels.
 
+Note
+    When a bounding box is created without any points, it creates an inverted
+    bounding box. Points can be added later and the bounding box will grow to
+    include them.
+
 SourceFiles
     treeBoundBoxI.H
     treeBoundBox.C
@@ -93,12 +98,6 @@ public:
 
     // Static data members
 
-        //- As per boundBox::greatBox, but with GREAT instead of VGREAT
-        static const treeBoundBox greatBox;
-
-        //- As per boundBox::invertedBox, but with GREAT instead of VGREAT
-        static const treeBoundBox invertedBox;
-
         //- Bits used for octant/point coding.
         //  Every octant/corner point is the combination of three faces.
         enum octantBit

src/parallel/distributed/distributedTriSurfaceMesh/distributedTriSurfaceMesh.C

@@ -891,11 +891,11 @@ Foam::distributedTriSurfaceMesh::independentlyDistributedBbs
 
     // Find bounding box for all triangles on new distribution.
 
-    // Initialise to inverted box (GREAT, -GREAT)
+    // Initialise to inverted box
     List<List<treeBoundBox>> bbs(Pstream::nProcs());
     forAll(bbs, procI)
     {
-        bbs[procI].setSize(1, treeBoundBox::invertedBox);
+        bbs[procI].setSize(1, treeBoundBox(boundBox::invertedBox));
     }
 
     forAll(s, triI)

src/sampling/probes/patchProbes.C

@@ -69,7 +69,7 @@ void Foam::patchProbes::findElements(const fvMesh& mesh)
     {
         // Collect mesh faces and bounding box
         labelList bndFaces(nFaces);
-        treeBoundBox overallBb(treeBoundBox::invertedBox);
+        treeBoundBox overallBb(boundBox::invertedBox);
 
         nFaces = 0;
         forAll(patchIDs, i)

src/sampling/sampledSet/patchCloud/patchCloudSet.C

@@ -74,7 +74,7 @@ void Foam::patchCloudSet::calcSamples
 
     labelList patchFaces(sz);
     sz = 0;
-    treeBoundBox bb(treeBoundBox::invertedBox);
+    treeBoundBox bb(boundBox::invertedBox);
     forAllConstIter(labelHashSet, patchSet_, iter)
     {
         const polyPatch& pp = mesh().boundaryMesh()[iter.key()];