[vtkusers] How to get actual zoom-factor of vtkCamera?

[Glen Lehmann]

Hi Adrian,

vtkCamera->Zoom is a helper method to take care of the changes  
necessary to "zoom", which depend on whether you're vtkCamera is  
perspective or parallel (see code below).  This is always done relative  
to the current ViewAngle/ParallelScale.

A GetZoom method could be confusing: is it relative to the initial view  
angle, or last view angle, or etc ...

For your purposes you'll have to pick and initial reference for zoom  
and calculate if from the ViewAngle/ParallelScale.

Cheers,
Glen


/ 
/----------------------------------------------------------------------- 
-----
// Change the ViewAngle (for perspective) or the ParallelScale (for  
parallel)
// so that more or less of a scene occupies the viewport.  A value > 1  
is a
// zoom-in. A value < 1 is a zoom-out.
void vtkCamera::Zoom(double amount)
{
   if (amount <= 0.0)
     {
     return;
     }

   if (this->ParallelProjection)
     {
     this->SetParallelScale(this->ParallelScale/amount);
     }
   else
     {
     this->SetViewAngle(this->ViewAngle/amount);
     }
}

On Nov 4, 2004, at 10:28 AM, Adrian Wyssmann wrote:

> Hi All
>
> How do I get the actual zoom-factor of a vtkCamera? I see only a  
> function to
> set the zoom.
>
> Thanks
>
> Adrian
>
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