Hi Dirk,
ok i try again.

I have a volumemodel of certain points which are shown on the screen with 
coordinates for example from -128 to 128 for XYZ. Then there is a "viewpoint" 
from which I look on this model. The viewpoint has at the beginning the same 
coordinates like the from-point in the Look-At definition.

Then i use the Navigator to rotate around the model or to zoom in or to change 
the at point. As long as I dont change at point or rotate an do just a zoom, 
everything is fine an i can just use the from-coordinates to set them for my 
viewpoint. The problem are the rotations and the move of the at-point because 
this changes not only the from coordinates but as well the up-vector and the 
at-point-coordinates. 

I need the viewpoint to send rays on the volumemodel. Since i use the navigator 
an do no model transformation my "viewpoint" needs to be recalculate instead.

Now i need either a method how to recalculate my "viewpoint" with the from, at 
and up values or a method which does it for me this or another way.

Hope this helps?

Simon


-------- Original-Nachricht --------
> Datum: Fri, 12 Oct 2007 08:28:03 -0500
> Von: Dirk Reiners <[EMAIL PROTECTED]>
> An: [email protected]
> Betreff: Re: [Opensg-users] How to get correct viewpoint from Look-At

> 
>       Hi Simon,
> 
> Simon Beisel wrote:
> > Hello everybody, i am currently working on my masters thesis and have
> > some problems calculating the right viewpoint on a volumemodel which
> > is implemented in OpenSG.
> > 
> > For my Calculations i need the viewpoint on the volume. 
> 
> Can you define what that is? Is it the from point, the at point, or 
> (most likely) the point in the model that's in the middle of the screen 
> or under the mouse cursor?
> 
> > the from-point is only the viewpoint as long as the at-point and the
> > up-vector stay unchanged. After rotating for example it is no longer
> > correct.
> 
> Rotating how? Using a Navigator?
> 
> > Is there a way to get directly the corresponding viewpoint or does it
> > have to be computed manually? In the second case, how can I compute
> > the viewpoint correct with the from, at and up values?
> > 
> > I would really appreciate if someone could help me or even post a
> > chunk of code which manages that problem.
> 
> Let's try the other way around: what do you want to do, what do you need 
> the viewpoint for? There might be an easy way to do what you want, if we 
> knew what you want. ;)
> 
>       Dirk
> 
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