[vtkusers] Anti-aliasing text - Performance

[Philip Schuchardt]

After investageting text rendering more deeply,  I have concluded that the 
implementation of the vtkTextActors has excellent performance. The 
performance is equivalent to straight FTGL(obviously since vtkTextActors use 
FTGL).  It just shows that vtkTextActors do not have very much overhead. 

I was trying to use the CaptionActor2D in my program.  For some reason I 
thought that the anti aliased vtkTextActor(FTGLPixmap) was causing the slow 
down.  Really,  the caption actor was noticeably slower and  under my tests, 
I found the CaptionActor2D to be 400% slower then just the plain 
vtkTextActor.

Philip Schuchardt

On Friday 06 April 2007 11:32 pm, Philip Schuchardt wrote:
> After testing and hacking up the vtkFreeTypeUtilities.cxx, I found out that
> anti-aliased fonts do not cause a significant performance hit.  I do not
> know openGL very well.  After skimming through the VTK source, it seems to
> me that VTK has an extra openGL overhead while rendering each actor.  The
> rendering overhead probably causing the performance hit while trying to
> render 1000 textactors.  In the next couple of weeks, I want to pound out a
> text manager that renders text more quickly, without the overhead.  This
> manager would also have text collision detection so string don't write over
> each other. Any suggestions?
>
> Philip Schuchardt
>
> On Wednesday 14 March 2007 4:19 pm, Philip Schuchardt wrote:
> > I'm trying to render over 1000 text actors at once and there is a huge
> > preformace hit. By default vtk uses anti-aliasing text for vtkTextActor
> > and vtkTextMapper.  I think the anti-aliasing is causing the large
> > preformace hit with that many actors.   I have a simalar openGL
> > application that has good performance without aliased fonts.  It appears
> > that turning off the anti aliasing in the vtkTextProperty was removed in
> > version 5.0.  Is there anyway any other way to turn off anti-aliasing for
> > text ie. making the text aliased?
> >
> > If there is no way to do this... I will probably end up calling openGL
> > directly.
> >
> > System:
> > Gentoo Linux
> > AMD64 X2 4400
> > Nvidia 7800GTX 256mb
> >
> > Thanks
> > Philip Schuchardt
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