ENH: refinementFeatures: make indexedOctree bounding box 3D

src/mesh/autoMesh/autoHexMesh/refinementFeatures/refinementFeatures.C

@@ -86,7 +86,16 @@ Foam::refinementFeatures::refinementFeatures
         const edgeList& edges = eMesh.edges();
 
         // Calculate bb of all points
-        const treeBoundBox bb(points);
+        treeBoundBox bb(points);
+
+        // Random number generator. Bit dodgy since not exactly random ;-)
+        Random rndGen(65431);
+
+        // Slightly extended bb. Slightly off-centred just so on symmetric
+        // geometry there are less face/edge aligned items.
+        bb = bb.extend(rndGen, 1E-4);
+        bb.min() -= point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
+        bb.max() += point(ROOTVSMALL, ROOTVSMALL, ROOTVSMALL);
 
         edgeTrees_.set
         (