Ensure composite polydata mapper has correct MTime

Rendering/OpenGL2/vtkCompositePolyDataMapper2.cxx

@@ -660,6 +660,18 @@ int vtkCompositePolyDataMapper2::CanUseTextureMapForColoring(vtkDataObject*)
   return this->CanUseTextureMapForColoringValue;
 }
 
+//-------------------------------------------------------------------------
+bool vtkCompositePolyDataMapper2::GetNeedToRebuildBufferObjects(
+  vtkRenderer *ren, vtkActor *act)
+{
+  if (vtkCompositePolyDataMapper2::Superclass::GetNeedToRebuildBufferObjects(ren, act) ||
+      (this->GetInput() && this->VBOBuildTime < this->GetInput()->GetMTime()))
+    {
+    return true;
+    }
+  return false;
+}
+
 //-------------------------------------------------------------------------
 void vtkCompositePolyDataMapper2::BuildBufferObjects(
   vtkRenderer *ren,

Rendering/OpenGL2/vtkCompositePolyDataMapper2.h

@@ -52,6 +52,10 @@ protected:
     std::map<vtkShader::Type, vtkShader *> shaders,
     vtkRenderer *ren, vtkActor *act);
 
+  // Description:
+  // Determine if the buffer objects need to be rebuilt
+  virtual bool GetNeedToRebuildBufferObjects(vtkRenderer *ren, vtkActor *act);
+
   // Description:
   // Build the VBO/IBO, called by UpdateBufferObjects
   virtual void BuildBufferObjects(vtkRenderer *ren, vtkActor *act);