Debug improvements in view factors

applications/utilities/preProcessing/viewFactorsGen/viewFactorsGen.C

@@ -235,8 +235,8 @@ int main(int argc, char *argv[])
     // Calculate total number of fine and coarse faces
     // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-    label nCoarseFaces = 0;      //total number of coarse faces
+    label nCoarseFaces = 0;      // total number of coarse faces
-    label nFineFaces = 0;        //total number of fine faces
+    label nFineFaces = 0;        // total number of fine faces
 
     const polyBoundaryMesh& patches = mesh.boundaryMesh();
     const polyBoundaryMesh& coarsePatches = coarseMesh.boundaryMesh();
@@ -256,7 +256,7 @@ int main(int argc, char *argv[])
             viewFactorsPatches[count] = QrpI.patch().index();
             nCoarseFaces += coarsePatches[patchI].size();
             nFineFaces += patches[patchI].size();
-            count ++;
+            count++;
         }
     }
 
@@ -267,6 +267,26 @@ int main(int argc, char *argv[])
 
     reduce(totalNCoarseFaces, sumOp<label>());
 
+    if (totalNCoarseFaces == 0)
+    {
+        WarningIn(args.executable())
+            << "No coarse faces detected: no rays." << nl
+            << "This is probably not intended: please reconsider case setup"
+            << endl;
+
+        return 0;
+    }
+
+    if (count == 0)
+    {
+        WarningIn(args.executable())
+            << "No radiation patches detected: no rays." << nl
+            << "This is probably not intended: please reconsider case setup"
+            << endl;
+
+        return 0;
+    }        
+    
     if (Pstream::master())
     {
         Info << "\nTotal number of coarse faces: "<< totalNCoarseFaces << endl;