How to change the color of the triangle according to the orientation of the camera and the normal vector of the triangle

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6

Thank you for your answer.
by looking for the vtk function, i found that the actor can use SetBackfaceProperty, which can solve the problem. anyway, thank you for your answer.

the complete code is
vtkSmartPointer backProperty = vtkSmartPointer::New();
backProperty->SetColor(colors->GetColor3d(“Red”).GetData());
actor->SetBackfaceProperty(backProperty);