ENH: viewFactorsGen: re-enable 2D. See #2560

This reverts the v2206 behaviour so does not include
the edge-integration (2LI) optimisation - it uses
the exact same code as v2206.

src/finiteVolume/fvMesh/singleCellFvMesh/singleCellFvMesh.C

@@ -53,6 +53,15 @@ void Foam::singleCellFvMesh::agglomerateMesh
         const polyPatch& pp = oldPatches[patchi];
         if (pp.size() > 0)
         {
+            if (agglom[patchi].size() != pp.size())
+            {
+                FatalErrorInFunction
+                    << "agglomeration on patch " << patchi
+                    << " (size " << pp.size()
+                    << ") is of size " << agglom[patchi].size()
+                    << exit(FatalError);
+            }
+
             nAgglom[patchi] = max(agglom[patchi])+1;
 
             forAll(pp, i)
@@ -229,6 +238,7 @@ void Foam::singleCellFvMesh::agglomerateMesh
         patchSizes[patchi] = coarseI-patchStarts[patchi];
     }
 
+    //patchFaces.setSize(coarseI);
     //Pout<< "patchStarts:" << patchStarts << endl;
     //Pout<< "patchSizes:" << patchSizes << endl;
 
@@ -398,7 +408,8 @@ void Foam::singleCellFvMesh::agglomerateMesh
 Foam::singleCellFvMesh::singleCellFvMesh
 (
     const IOobject& io,
-    const fvMesh& mesh
+    const fvMesh& mesh,
+    const bool doInit
 )
 :
     fvMesh(io, Zero, false),
@@ -478,6 +489,12 @@ Foam::singleCellFvMesh::singleCellFvMesh
     }
 
     agglomerateMesh(mesh, agglom);
+
+    // initialise all (lower levels and current)
+    if (doInit)
+    {
+        fvMesh::init(true); // initialise fvMesh and underlying levels
+    }
 }
 
 
@@ -485,7 +502,8 @@ Foam::singleCellFvMesh::singleCellFvMesh
 (
     const IOobject& io,
     const fvMesh& mesh,
-    const labelListList& patchFaceAgglomeration
+    const labelListList& patchFaceAgglomeration,
+    const bool doInit
 )
 :
     fvMesh(io, Zero, false),
@@ -556,12 +574,17 @@ Foam::singleCellFvMesh::singleCellFvMesh
     )
 {
     agglomerateMesh(mesh, patchFaceAgglomeration);
+    // initialise all (lower levels and current)
+    if (doInit)
+    {
+        fvMesh::init(true); // initialise fvMesh and underlying levels
+    }
 }
 
 
-Foam::singleCellFvMesh::singleCellFvMesh(const IOobject& io)
+Foam::singleCellFvMesh::singleCellFvMesh(const IOobject& io, const bool doInit)
 :
-    fvMesh(io),
+    fvMesh(io, doInit),
     patchFaceAgglomeration_
     (
         IOobject

src/finiteVolume/fvMesh/singleCellFvMesh/singleCellFvMesh.H

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2019 OpenCFD Ltd.
+    Copyright (C) 2019,2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -155,7 +155,12 @@ public:
     // Constructors
 
         //- Construct from fvMesh and no agglomeration
-        singleCellFvMesh(const IOobject& io, const fvMesh&);
+        singleCellFvMesh
+        (
+            const IOobject& io,
+            const fvMesh&,
+            const bool doInit=true
+        );
 
         //- Construct from fvMesh and agglomeration of boundary faces.
         //  Agglomeration is per patch, per patch face index the agglomeration
@@ -164,11 +169,13 @@ public:
         (
             const IOobject& io,
             const fvMesh&,
-            const labelListList& patchFaceAgglomeration
+            const labelListList& patchFaceAgglomeration,
+            const bool doInit=true
         );
 
         //- Read from IOobject
-        singleCellFvMesh(const IOobject& io);
+        singleCellFvMesh(const IOobject& io, const bool doInit=true);
+
 
     // Member Functions