Volume disappears when mixing with polydata [VTK 8.2 - bug]

[stavbodik (סתיו בודיק)]

So here is some work around that working :

Surface and volume rendering in the same render

I create a vtkpolydata and a vtkImagedata ,add a vtkActor and vtkVolume to the same render,the vtkpolydata is a closed surface, and intersect with the volume . when I set the vtkActor opacity to 1, actor->GetProperty()->SetOpacity(1); it looks all right,but when i set the opacity to 0.5, actor->GetProperty()->SetOpacity(0.5); it looks strange , like the volume covers the suface , I don’t know what caused this problem, Can you give me some advice? thanks

Actually I see that

vtkUnstructuredGridVolumeRayCastMapper.cxx

and

vtkFixedPointVolumeRayCastMapper.cxx

Both doing Capture the zbuffer but slightly different code , will go compare to see if its the same.