How to apply mask to a transformed vtkVolume

I can apply a binary mask to a vtkVolume by using SetMaskInput()(in vtkGPUVolumeRayCastMapper class).


The vtkVolume has the mask effects(hole) as I aspect. The vtkVolume has not been transformed. If the vtkVolume is transformed (I use setUserMatrix() ), the mask has no effect. I try to use vtkImageReslice to apply a matrix to a vtkImageData, and then use the image data for SetMaskInput(). But I failed. Is there any way to solve the problem? Thanks in advance.