[osg-users] setLODScale affecting near far planes?

Tomlinson, Gordon GTOMLINSON at overwatch.textron.com
Mon Sep 22 08:45:27 PDT 2008


Culling IS done against the near and far clip, this is standard
operating procedure of OGL and OSG 


Gordon

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Gordon Tomlinson

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-----Original Message-----
From: osg-users-bounces at lists.openscenegraph.org
[mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of Smeenk,
R.J.M. (Roland)
Sent: Monday, September 22, 2008 11:36 AM
To: OpenSceneGraph Users
Subject: Re: [osg-users] setLODScale affecting near far planes?


Paul,

As far as I know default OSG culling is only done against the sides and
not against the near and far plane.
See:

        enum MaskValues
        {
            NO_CULLING                  = 0x0,
            VIEW_FRUSTUM_SIDES_CULLING  = 0x1,
            NEAR_PLANE_CULLING          = 0x2,
            FAR_PLANE_CULLING           = 0x4,
            VIEW_FRUSTUM_CULLING        = VIEW_FRUSTUM_SIDES_CULLING|
                                          NEAR_PLANE_CULLING|
                                          FAR_PLANE_CULLING,
            SMALL_FEATURE_CULLING       = 0x8,
            SHADOW_OCCLUSION_CULLING    = 0x10,
            DEFAULT_CULLING             = VIEW_FRUSTUM_SIDES_CULLING|
                                          SMALL_FEATURE_CULLING|
                                          SHADOW_OCCLUSION_CULLING,
            ENABLE_ALL_CULLING          = VIEW_FRUSTUM_CULLING|
                                          SMALL_FEATURE_CULLING|
                                          SHADOW_OCCLUSION_CULLING
        }; 

--
Roland

> -----Original Message-----
> From: osg-users-bounces at lists.openscenegraph.org
> [mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of Paul 
> Martz
> Sent: maandag 22 september 2008 16:46
> To: 'OpenSceneGraph Users'
> Subject: Re: [osg-users] setLODScale affecting near far planes?
> 
> > Hi all again,
> > 
> > Robert: for you last question; yes, I have near/far culling enabled 
> > and the near/far setting is
> compute_near_far_using_bounding_volume. If
> > the near far modification that is taking place should be
> very small,
> > somehow I am still getting quite significant jumps because some 
> > objects near the camera get culled when I would not like that to 
> > happen. When I enable culling for near/far planes, it seems
> like osg
> > takes into account my preferred near/far planes and is NOT 
> > auto-computing. It does do some re computation as I change the 
> > LODScale. Why does this happen?
> 
> You have said on multiple occasions that you are "enabling near/far 
> culling"
> -- What exactly do you mean by that? Near/far culling is always 
> enabled in OSG and OpenGL, so I'm curious to know what function call 
> you are making that you believe is enabling near/far culling.
> 
> > Paul:
> > >Do you get the same behavior when viewing your database in
> osgviewer
> > >and hitting the * and / keys?
> > >   -Paul
> > 
> > Sorry Paul, but it is hard for me to say, because with osgviewer I 
> > only notice the terrain loosing or gaining detail, but since I am 
> > unable to dump the camera information in osgviewer I cannot
> compare it
> > to my application's printouts of near far planes, but
> thanks for the
> > advice.
> 
> If you don't get the dame behavior in osgviewer, then most likely this

> is a bug in your own application somewhere, and not a problem in OSG.
> 
> You can dump the osgviewer camera information by editing the osgviewer

> source.
>    -Paul
> 
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