[vtkusers] vtkFixedPointVolumeRayCastMapper How to GetGradientEstimator ??

[wassim_belhadj at topnet.tn]

Hi 

I used vtkVolumeRayCastMapper now I want to use
vtkFixedPointVolumeRayCastMapper.

I got some compilation errors   :

'GetGradientEstimator' : is not a member of
'vtkFixedPointVolumeRayCastMapper'	


'SetVolumeRayCastFunction' : is not a member of
'vtkFixedPointVolumeRayCastMapper'	


How to solve these errors?

Thank you in advance