Merge topic 'fix-extents-rect-grid-cell-data'

e0d10d6d Fix extents for cell data with vtkRectilinearGrid

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !6916

Rendering/VolumeOpenGL2/vtkVolumeTexture.cxx

@@ -893,6 +893,12 @@ void vtkVolumeTexture::ComputeBounds(VolumeBlock* block)
       origin[cc] = bounds[2 * cc];
     }
     rGrid->GetExtent(block->Extents);
+    if (this->IsCellData)
+    {
+      block->Extents[1]--;
+      block->Extents[3]--;
+      block->Extents[5]--;
+    }
   }
 
   int swapBounds[3];