[vtkusers] volume rendering with texture mapping is slow.

[Jianlong Zhou]

Hi, vtkusers,

I use vtkVolumeTextureMapper2D as the mapper in a volume visualization application. It 
should be faster than ray casting in principle. But I compared texture mapping and ray 
casting with the same data set and same transfer function. I found that the frame rate of 
texture mapping is much slower than ray casting method. Is there anyone know what the 
problem is? I use vtkVolumeTextureMapper2D like followings, no other setting are made 
for this mapper. My graphics card is nVidia GeForce DDR.

vtkVolumeTextureMapper2D *textureMapper =vtkVolumeTextureMapper2D::New();
   textureMapper->SetInput(reader->GetOutput());

Thank you very much.

regards,
Jianlong