[vtkusers] What's a good way to do volume rendering when the capability of graphics hardware is unknown

[Weiguang guan]

Hi everyone,

If you have an answer or suggestions regarding the question in the 
subject line, please share them. Thanks.

Using vtkSmartVolumeMapper and SetRequestedRenderModeToDefault() is 
certainly designed for this purpose. But it has some issues:

(1) If GPU ray casting is not supported, then it will try 3D texture 
mapping. Simon ESNEAULT reported a bug that sneaked into 
vtkVolumeTextureMapper3D in v5.5 or v5.6 five years ago that causes 
dramatic slow down. The problem hasn't been fixed so far, and it is not 
likely to be fixed soon as the mapper is considered as "depreciated".

(2) GPU ray casting is supported on my laptop and desktop, but I am not 
sure it can do LOD. They dynamic rate is not very good to be 
interactive. I tried to play with SetInteractiveUpdateRate(double) but 
it didn't seem have any effect. Any suggestion? Thanks.

Best,
Weiguang