[vtkusers] Font rendering performance issues with VTK 4.2.2/win XP/.NET

[aborsic at sc-aip.com]

Dear All,

I'm experiencing a strange problem. I'm posting to check if anybody else has 
incurred in anything similar or has any suggestion ragarding the matter.

I'm using VTK on a laptop with windows XP and VS.NET 7.0

In the past I was used to run some python scripts with the original VTK 4.0 
distribution from Kitware, and everything was fine.

I have decided thereafter to dowload VTK 4.2.2 and compile it on my machine. 
The strange thing is that now the rendering of scenes containing text is 
extremely slow. The same thing happens from tcl and Cxx as well. For example 
vtkSDI takes about 13 seconds to render (due to the presence of the axes 
labels in the scene, as I will explain later). Similary most of the examples 
under Annotation are exceedengly slow.

Things do not change when installing the original 4.2.2 VTK distribution from 
Kitware.

***

I have decided therefore to investigate the matter furter, and tryied to do 
some performance analysis and execute code step by step with a debug version 
of VTK.

As anticipated, the profiling on the vtkSDI application tells that the 
application is spending about 13 seconds to render a very simple scene, and 
that most of this time is spent in rendering a vtkCubeAxesActor2D that 
encloses the dataset. Some further digging into the code showed that actually 
almost all the time is spent rendering the text labels of the axes.

By just removing from the scene the axes and recompiling, vtkSDI is capable of 
opening large vtk datasets and showing them with good performance on my 
machine.

SampleMFC shows similar problems due to the presence of the "Hello World" on 
the bottom of the viewport. Removing the text again makes the application run 
smooth. Similar considerations apply to the annotation examples, they are slow 
(but under cxx, python and tcl) due to the presence of text labels.

***

I'm a bit puzzled by the issue, and I'm not really sure on what to do. I will 
try to investigate differences in the source code between vtk 4.0 and 4.2 with 
regard to the overlay rendering of fonts.

Has anybody experienced anything similar, or is anybody aware of particular 
changes regarding font rendering from 4.0 to 4.2 ?

Thanks in andvance for any suggestion,

Best Regards,

Andrea.

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