[vtkUsers] using OpenGL acceleration for volume rendering

[Patrick Lagace]

>
> I've just tried using vtkVolumeTextureMapper2d and then
> vtkOpenGLVolumeTextureMapper2d to do some volume rendering, just to
> compare them; and I can't seem to see any difference in performance.

When you create a vtkVolumeTextureMapper2D, it creates in fact a
vtkOpenGLVolumeTextureMapper2d  (go see vtkVolumeTextureMapper2D::New()  and
vtkGraphicsFactory.cxx   if you want to know exactly how it is done).

Under Windows, this is the default behavior for vtkVolumeTextureMapper2D, under linux & MESA,
it would create a vtkMesaVolumeTextureMapper2D...

> The
> code is running on a Windows 2000 machine with a GeForce card in it that
> is supposed to do wonderful things with texture mapping, so I'm curious
> if either there is something I need to do for vtk to take advantage of
> hardware acceleration, or if the bottleneck in the rendering process is
> not the texture mapping but some other part of it which remains CPU
> intensive despite help from the GeForce card.

So... using one class or another will have the exact same performance on your system.  If your
application is slow... it is not because it is not 3d-accelerated (from the vtk point of
view), but because it's graphic-intensive or maybe you have a 3d driver problem.



Patrick.