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

[Rahul Jain]

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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