[osg-users] how to zoom in and out in orthographic projection

[Mike Weiblen]

Could you pls answer Paul's question of "how did you implement the
zoom in your projection"?
What exactly do you mean by "zoom" in an orthographic projection?

-- mew





On Sun, May 4, 2008 at 9:28 AM, Rahul Jain <rahulj at darshan3d.com> wrote:
> Hi Paul,
>  Thanks for the answer and sorry for being so desperate last time.
>  We tried the approach you mentioned by writing a node visitor and
>  setting the range node(PIXEL_SIZE_ON_SCREEN)  for  LOD nodes. But the
>  effect i am getting is completely opposite, as i zoom in the high
>  resolution data disappears and when i zoom out high resolution data is
>  loaded. I tried the same thing with perspective projection also and i am
>  getting the same effect. I am not able to understand what am i doing wrong.
>  cheers
>  RJ
>
>
>
>
>  Paul Melis wrote:
>  > Posting your question just once and waiting a bit for an answer would be
>  > nice...
>  >
>  > santosh wrote:
>  >
>  >> how to do zoom in and out in orthographic projection?
>  >> As I zoom in  the detailed geometry should be loaded .
>  >>
>  >> Right now I am scaling the  geometry but in this method the details are
>  >> not getting loaded.
>  >>
>  >
>  > How did you implement the zoom in your projection, just by changing the
>  > viewport to be smaller? In that case the distance from the viewpoint to
>  > your objects doesn't change and therefore the same LOD-level will
>  > continue to be selected, as the default RangeMode for an osg::LOD is
>  > DISTANCE_FROM_EYE_POINT. Changing it to PIXEL_SIZE_ON_SCREEN should make
>  > your LODs switch to more detailed models if you zoom in.
>  >
>  > Paul
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>  >
>  >
>
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-- 
Mike Weiblen -- Austin Texas USA -- http://mew.cx/