[Paraview] Performance using ImmediateModeRenderingOff in pure vtk vs. Paraview

[Max Schoebinger]

Hello,

In our lab we have a home grown vtk/itk based application framework for 
medical applications. I discovered a performance problem while working 
with Triangular meshes loaded from STL-Files. If the vtkProperties 
change (e.g. opacity), each rendering update takes extremely long 
(>10s). Using paraview, updates are possible at interactive speed 
(<0.5s). I tracked down the problem to a minimal example only using pure 
vtk (see attachment) and discovered, that in the function 
vtkOpenGLPolyDataMapper::RenderPiece(...) new display lists are 
generated each time the properties of the actor have been modified. This 
is not the case, if ImmediateModeRendering is on. So my situation is: if 
ImmideateModeRendering is on, everything works as fast as expected, if 
ImmediateModeRendering is off, rendering updates are is really slow.

Now my question: how is rendering in paraview organized (optimized)? The 
render updates at opacity changes are always fast, no matter if 
ImmediateModeRendering is on or off.

Some Notes:

I am working on a laptop (2Ghz Pentium M, 2Gb RAM) under windows xp 
service pack 2.
My Compiler is Visual Studio .NET 2002
My graphics card is an ATI Mobility Radeon X600 with 128 MB RAM.
I am using the latest driver for the graphics adapter.
The STL-File I am working with has 30947 points and 61818 cells.
The problem does not appear on NVidia graphics adapters.

Thanks for any hints,

Max
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