[vtkusers] Cool sample does not work, need help !!

[de Boer Ingo]

Hi,

is there no one to help on this ??

greets
  Ingo

---
Dr.-Ing. Ingo H. de Boer

Polytec GmbH
Polytec-Platz 1-7, 76337 Waldbronn, Germany
phone: ++49 7243 604 106
fax  : ++49 7243 604 255
 

> -----Original Message-----
> From: de Boer Ingo 
> Sent: Monday, September 20, 2004 12:26 PM
> To: Andrew Maclean; vtkusers at vtk.org
> Cc: vidyadhar at lucidindia.net
> Subject: RE: [vtkusers] Cool sample does not work, need help !!
> 
> 
> Hi,
> 
> I tried the frustum planes. But it still does not work for
> perspective projection, only for parallel projection.
> Did I do anything wrong in my programming, did I miss something ?
> 
> Any further hints on this sample ? This new sample uses the
> frustum planes...
> 
> 
> greets
>   Ingo
> 
> ---
> Dr.-Ing. Ingo H. de Boer
> 
> Polytec GmbH
> Polytec-Platz 1-7, 76337 Waldbronn, Germany
> phone: ++49 7243 604 106
> fax  : ++49 7243 604 255
>  
> 
> > -----Original Message-----
> > From: Andrew Maclean [mailto:a.maclean at cas.edu.au]
> > Sent: Wednesday, September 15, 2004 1:00 AM
> > To: de Boer Ingo; vtkusers at vtk.org
> > Subject: RE: [vtkusers] Cool sample does not work, need help !!
> > 
> > 
> > It is definitely a cool sample!
> > 
> > As you indicate, what you have written works perfectly well 
> > for parallel
> > projections. If you look at DisplayToWorld() in your code, 
> there is no
> > perspective transform being applied to the coordinates, so 
> Pt4[3] will
> > always be 1. You are simply taking the viewport coordinates 
> > and converting
> > them to world coordinates. This is fine for parallel 
> > projections but not for
> > perspective projections.
> > 
> > For perspective projections, you actually need the view 
> > frustum and you can
> > get the planes bounding this from 
> > vtkCamera::GetFrustrumPlanes(), remember
> > :- the "aspect" is the width/height of the viewport. My 
> > initial approach
> > would be to construct a frustum from these planes and use the 
> > edges of the
> > nearest face as your bounding rectangle. This will also work 
> > for parallel
> > projections, however the frustum will simply become a cube in 
> > this case.
> > 
> > An alternative approach may be to use vtkCamera::
> > GetPerspectiveTransformMatrix() and 
> > vtkCamera::GetViewTransformMatrix() to
> > directly map the viewport bounds to word coordinates. However 
> > I think that
> > using vtkCamera::GetFrustrumPlanes() will be a better approach.
> > 
> > 
> > Let me know how this works. We (the users group) would love 
> > to see the final
> > result!
> > 
> > 
> > Regards,
> >    Andrew
> > 
> > ___________________________________________
> > Andrew J. P. Maclean
> > Centre for Autonomous Systems
> > The Rose Street Building J04
> > The University of Sydney  2006  NSW
> > AUSTRALIA
> > Ph: +61 2 9351 3283
> > Fax: +61 2 9351 7474
> > URL: http://www.cas.edu.au/
> > ___________________________________________
> > 
> > 
> > 
> > 
> > 
> > -----Original Message-----
> > From: de Boer Ingo [mailto:I.deBoer at polytec.de] 
> > Sent: Friday, 10 September 2004 21:18
> > To: vtkusers at vtk.org
> > Cc: vidyadhar at lucidindia.net
> > Subject: [vtkusers] Cool sample does not work, need help !!
> > 
> > Hi all,
> > 
> > Vidyadhar and I are working on this cool zoom sample.
> > We have a cube in a large and small renderer. Now, when
> > you zoom into the large renderer, you see a red rectangle
> > in the small renderer to show you the zoomed ROI from
> > the large renderer... well... play with it, you'll get it ;)
> > 
> > There is still a problem :(
> > 
> > The sample only works okay in parallel projection. The
> > perspective projection does not work !!
> > 
> > So, this goes out to all the VTK gurus to take a look at
> > this. This sample could also be a nice one for the VTK CVS
> > and very usefull to some other users.
> > 
> > You can toogle the perspective/parallel with the line
> > 
> > #define _WORKING_SAMPLE_
> > 
> > 
> > greets
> >   Ingo
> > 
> > 
> > ---
> > Dr.-Ing. Ingo H. de Boer
> > 
> > Polytec GmbH
> > Polytec-Platz 1-7, 76337 Waldbronn, Germany
> > phone: ++49 7243 604 106
> > fax  : ++49 7243 604 255
> > 
> > 
> > 
> 
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