[vtkusers] huge speed difference between on-screen and off-screen rendering

[David Gobbi]

Hi Jorrit,

The off-screen rendering is done without any hardware acceleration.
There are GL extensions to allow off-screen rendering with acceleration,
but very few OpenGL drivers support these extensions.

It is possible that in the future VTK could be enhanced to do
hardware-accelerated offscreen rendering with the drivers/cards
that support it, but for now you're out of luck.

You could try tricks like using a double-buffered window, not mapping
the window (you'd have to do this via C++ or via a vtkTkRenderWidget or
some such because you couldn't do it with a raw vtkRenderWindow), and then
grabbing the image from the back buffer.  That might work, but I don't
think anyone has tested it.

 - David

--
  David Gobbi, MSc                       dgobbi at irus.rri.ca
  Advanced Imaging Research Group
  Robarts Research Institute, University of Western Ontario

On Wed, 23 Jan 2002, Schaap, J.A. (LKEB) wrote:

> Hi gurus,
>
> I'm using both the vtkWin32OpenGLRenderWindow and the vtkWin32OffscreenRenderWindow in my applications. I noticed however a huge speed difference between these two different render methods. Did
> anybody else notice this, and does anybody know a solution to speed-up the offscreen rendering?
>
> Thanks, Jorrit
>
> PS: my platform is Win2000 Professional, 512MB, GeForce3, Pentium III 800MHz
>
>
>
>
>
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