This is how it is in OSG  and all other Scene graphs I have ever worked with 
and I have work with most

Without meaning to sound rude, I would say 

Get used to it in OSG as it not likely to change in how's its done 


Gordon
Product Manager 3d
__________________________________________________________
Gordon Tomlinson
Email  : gtomlinson @ overwatch.textron.com
__________________________________________________________


-----Original Message-----
From: [email protected] 
[mailto:[email protected]] On Behalf Of Gianluca Natale
Sent: Tuesday, August 11, 2009 6:36 AM
To: 'OpenSceneGraph Users'
Subject: Re: [osg-users] about the bounding sphere of a geode computed by OSG

I cannot completely agree.

I mean that I know that the real perfect bounding sphere is computationally 
expensive, but in many cases (solid objects) it should be computed just once 
(since BoundingSphere& node::getBound() checks if the bounding sphere has been 
already computed), when the object is created.
The global bounding sphere might affect the fitting operation a lot. In case of 
objects like spheres or discs, the bounding sphere computed by OSG might be 
much greater than strictly required.




-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Simon Hammett
Sent: martedì 11 agosto 2009 12.00
To: OpenSceneGraph Users
Subject: Re: [osg-users] about the bounding sphere of a geode computed by OSG

Calculating the perfect bounding sphere is an expensive operation.
You need to calc the convex hull which is O(n log n).
osg uses a fast approximation which is generally good enough.

2009/8/11 Gianluca Natale <[email protected]>:
> Hi All,
> I'm having problem computing the global bounding sphere of my model.
> I debugged OSG (2.8.0) and discovered that the bounding sphere of a 
> geode (BoundingSphere Geode::computeBound()) is computed as the 
> bounding sphere of the bounding box that includes all its drawables 
> !?!
>
>
>
> Why that?
>
> Shouldn't it be the global bounding sphere of the drawables, merging 
> the single bounding spheres of all the drawables?
>
>
>
> So, a drawable that represents a sphere should have as bounding sphere 
> itself, but this is not true with the computation OSG performs. It is 
> larger than strictly required.
>
>
>
> Thanks,
> Gianluca Natale
>
>
>
> _______________________________________________
> osg-users mailing list
> [email protected]
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.
> org
>
>



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