Re: [osg-users] bounding box of culled geometry

[OpenSceneGraph Users]

Hi Renzo,

On Thu, 15 Oct 2020 at 09:05, OpenSceneGraph Users <
osg-users@lists.openscenegraph.org> wrote:

> thanks for pointing out how cull traversal operates.
>
> Yes, it might be I am searching in the wrong direction. I need to get the
> minimum and the maximum Z coordinate of the geometry vertices in order to
> apply a color range. This is quite easy to do for the whole geometry but I
> would know if there is a way just for the vertices inside the view frustum.
>

The CullVisitor maintains the near and far values used in the view frustum
so after the cull traversal you should be able query the settings.  See
CullVisitor::getCalculatedNearPlane() and getCalculatedFarPlane()

Robert.

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Re: [osg-users] bounding box of culled geometry

[OpenSceneGraph Users]

  

Hi Wojtek,

it looks interesting. I do not have a shadowed scene but I will try
it, thanks.

Regards,
Renzo 

On 15-Oct-20 2:54 PM, OpenSceneGraph
  Users wrote:


  
  
Hi Renzo,
  
  
  You may look at osgShadow\MinimalCullBoundsShadowMap.cpp.
It scans RenderBins and compute bounds of culled drawables
to optimize shadow map resolution. 
  
  
  Cheers,
  Wojtek Lewandowski

  
  
  
czw., 15 paź 2020 o
  12:40 OpenSceneGraph Users 
  napisał(a):


   
Hi Werner,

I do not know if I have found the code that you are
suggesting. I see that CullVisitor could help to find the
near and far plane, however with Z I meant the world
vertical axis, not the axis of the view frustum.

Regards,
Renzo

On 15-Oct-20 11:25 AM, OpenSceneGraph Users wrote:


  Hi Renzo,
Maybe a node visitor with z-near and z-far as parameter
is a possible approach.
Werner
  
  
  On 15. Oktober 2020 09:46:57
MESZ, OpenSceneGraph Users 
wrote:
 
  Hi Robert,
  
  On 14-Oct-20 3:56 PM, OpenSceneGraph Users wrote:
  
  

  Hi Renzo,
  
  
  
On Wed, 14 Oct
  2020 at 12:00, OpenSceneGraph Users 
  wrote:


  I am using
  osg::Drawable::getBoundingBox() to
  retrieve the bounding box around the whole
  geometry. Is there a similar short way to
  get the equivalent box for just the culled
  geometry or do I need to write my own
  procedure?



Culling isn't related to the nodes
  directly, but to a traversersal of the scene
  graph that compares the bounding shere's of
  internal nodes of the scene graph and the
  bounding boxes of the drawable leaves. 
  Culling can happen at any point in the
  hierarchy - it can cull right up at the top
  node in the scene graph if the scene is
  outside the view frustum.


Within the cull traversal there is no
  tracking of culled or non culling bounding
  boxes, a cull test is done and the bool result
  used directly.  There isn't a "bounding box"
  or "bounding sphere" for culled or non culled
  objects.  All the cull traversal cares about
  is building a list of drawables leaves that
  pass the view frustum test, there is no
  tracking of any objects that are culled - this
  would be a crazy waste of CPU resources.



I have to ask, why do you want a bounding
  box of culled objects - what is the high level
  problem you are trying to solve?  It may well
  be that you are asking the wrong question
  thinking about the task you have in the wrong
  way.



Robert.

  

  
  
  thanks for pointing out how cull traversal operates.
  
  Yes, it might be I am searching in the wrong
  direction. I need to get the minimum and the maximum Z
  coordinate of the geometry vertices in order to apply
  a color range. This is quite easy to do for the whole
  geometry but I would know if there is a way just for
  the vertices inside the view frustum.
 

Re: [osg-users] bounding box of culled geometry

[OpenSceneGraph Users]

Hi Renzo,

You may look at osgShadow\MinimalCullBoundsShadowMap.cpp. It scans
RenderBins and compute bounds of culled drawables to optimize shadow map
resolution.

Cheers,
Wojtek Lewandowski

czw., 15 paź 2020 o 12:40 OpenSceneGraph Users <
osg-users@lists.openscenegraph.org> napisał(a):

>
> Hi Werner,
>
> I do not know if I have found the code that you are suggesting. I see that
> CullVisitor could help to find the near and far plane, however with Z I
> meant the world vertical axis, not the axis of the view frustum.
>
> Regards,
> Renzo
>
> On 15-Oct-20 11:25 AM, OpenSceneGraph Users wrote:
>
> Hi Renzo,
> Maybe a node visitor with z-near and z-far as parameter is a possible
> approach.
> Werner
>
>
> On 15. Oktober 2020 09:46:57 MESZ, OpenSceneGraph Users
>  
> wrote:
>>
>>
>> Hi Robert,
>>
>> On 14-Oct-20 3:56 PM, OpenSceneGraph Users wrote:
>>
>> Hi Renzo,
>>
>> On Wed, 14 Oct 2020 at 12:00, OpenSceneGraph Users <
>> osg-users@lists.openscenegraph.org> wrote:
>>
>>> I am using osg::Drawable::getBoundingBox() to retrieve the bounding box
>>> around the whole geometry. Is there a similar short way to get the
>>> equivalent box for just the culled geometry or do I need to write my own
>>> procedure?
>>>
>>
>> Culling isn't related to the nodes directly, but to a traversersal of the
>> scene graph that compares the bounding shere's of internal nodes of the
>> scene graph and the bounding boxes of the drawable leaves.  Culling can
>> happen at any point in the hierarchy - it can cull right up at the top node
>> in the scene graph if the scene is outside the view frustum.
>>
>> Within the cull traversal there is no tracking of culled or non culling
>> bounding boxes, a cull test is done and the bool result used directly.
>> There isn't a "bounding box" or "bounding sphere" for culled or non culled
>> objects.  All the cull traversal cares about is building a list of
>> drawables leaves that pass the view frustum test, there is no tracking of
>> any objects that are culled - this would be a crazy waste of CPU resources.
>>
>> I have to ask, why do you want a bounding box of culled objects - what is
>> the high level problem you are trying to solve?  It may well be that you
>> are asking the wrong question thinking about the task you have in the wrong
>> way.
>>
>> Robert.
>>
>>
>> thanks for pointing out how cull traversal operates.
>>
>> Yes, it might be I am searching in the wrong direction. I need to get the
>> minimum and the maximum Z coordinate of the geometry vertices in order to
>> apply a color range. This is quite easy to do for the whole geometry but I
>> would know if there is a way just for the vertices inside the view frustum.
>>
>> Regards,
>> Renzo
>>
>> --
>>
>> osg-users mailing 
>> listosg-users@lists.openscenegraph.orghttp://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>>
>>
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>
>
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Re: [osg-users] bounding box of culled geometry

[OpenSceneGraph Users]

  

Hi Werner,

I do not know if I have found the code that you are suggesting. I
see that CullVisitor could help to find the near and far plane,
however with Z I meant the world vertical axis, not the axis of the
view frustum.

Regards,
Renzo

On 15-Oct-20 11:25 AM, OpenSceneGraph
  Users wrote:


  
  Hi Renzo,
Maybe a node visitor with z-near and z-far as parameter is a
possible approach.
Werner
  
  
  On 15. Oktober 2020 09:46:57 MESZ,
OpenSceneGraph Users 
wrote:
 
  Hi Robert,
  
  On 14-Oct-20 3:56 PM,
OpenSceneGraph Users wrote:
  
  

  Hi Renzo,
  
  
  
On Wed, 14 Oct 2020 at
  12:00, OpenSceneGraph Users 
  wrote:


  I am using
  osg::Drawable::getBoundingBox() to retrieve the
  bounding box around the whole geometry. Is there a
  similar short way to get the equivalent box for
  just the culled geometry or do I need to write my
  own procedure?



Culling isn't related to the nodes directly, but to
  a traversersal of the scene graph that compares the
  bounding shere's of internal nodes of the scene graph
  and the bounding boxes of the drawable leaves. 
  Culling can happen at any point in the hierarchy - it
  can cull right up at the top node in the scene graph
  if the scene is outside the view frustum.


Within the cull traversal there is no tracking of
  culled or non culling bounding boxes, a cull test is
  done and the bool result used directly.  There isn't a
  "bounding box" or "bounding sphere" for culled or non
  culled objects.  All the cull traversal cares about is
  building a list of drawables leaves that pass the view
  frustum test, there is no tracking of any objects that
  are culled - this would be a crazy waste of CPU
  resources.



I have to ask, why do you want a bounding box of
  culled objects - what is the high level problem you
  are trying to solve?  It may well be that you are
  asking the wrong question thinking about the task you
  have in the wrong way.



Robert.

  

  
  
  thanks for pointing out how cull traversal operates.
  
  Yes, it might be I am searching in the wrong direction. I need
  to get the minimum and the maximum Z coordinate of the
  geometry vertices in order to apply a color range. This is
  quite easy to do for the whole geometry but I would know if
  there is a way just for the vertices inside the view frustum.
  
  Regards,
  Renzo
  
  
osg-users mailing list
osg-users@lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org


  
  
  
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Re: [osg-users] bounding box of culled geometry

[OpenSceneGraph Users]

Hi Renzo,
Maybe a node visitor with z-near and z-far as parameter is a possible approach.
Werner

On 15. Oktober 2020 09:46:57 MESZ, OpenSceneGraph Users 
 wrote:
>
>Hi Robert,
>
>On 14-Oct-20 3:56 PM, OpenSceneGraph Users wrote:
>
>Hi Renzo,
>
>
>On Wed, 14 Oct 2020 at 12:00, OpenSceneGraph Users
> wrote:
>
>I am using osg::Drawable::getBoundingBox() to retrieve the bounding box
>around the whole geometry. Is there a similar short way to get the
>equivalent box for just the culled geometry or do I need to write my
>own procedure?
>
>
>Culling isn't related to the nodes directly, but to a traversersal of
>the scene graph that compares the bounding shere's of internal nodes of
>the scene graph and the bounding boxes of the drawable leaves.  Culling
>can happen at any point in the hierarchy - it can cull right up at the
>top node in the scene graph if the scene is outside the view frustum.
>
>
>Within the cull traversal there is no tracking of culled or non culling
>bounding boxes, a cull test is done and the bool result used directly. 
>There isn't a "bounding box" or "bounding sphere" for culled or non
>culled objects.  All the cull traversal cares about is building a list
>of drawables leaves that pass the view frustum test, there is no
>tracking of any objects that are culled - this would be a crazy waste
>of CPU resources.
>
>
>I have to ask, why do you want a bounding box of culled objects - what
>is the high level problem you are trying to solve?  It may well be that
>you are asking the wrong question thinking about the task you have in
>the wrong way.
>
>
>Robert.
>
>
>thanks for pointing out how cull traversal operates.
>
>Yes, it might be I am searching in the wrong direction. I need to get
>the minimum and the maximum Z coordinate of the geometry vertices in
>order to apply a color range. This is quite easy to do for the whole
>geometry but I would know if there is a way just for the vertices
>inside the view frustum.
>
>Regards,
>Renzo
>
>
>
>
>
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>osg-users mailing list
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>http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
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Re: [osg-users] bounding box of culled geometry

[OpenSceneGraph Users]

  

Hi Robert,

On 14-Oct-20 3:56 PM, OpenSceneGraph
  Users wrote:


  
  
Hi Renzo,



  On Wed, 14 Oct 2020 at
12:00, OpenSceneGraph Users 
wrote:
  
  
I am using
osg::Drawable::getBoundingBox() to retrieve the bounding
box around the whole geometry. Is there a similar short
way to get the equivalent box for just the culled
geometry or do I need to write my own procedure?
  
  
  
  Culling isn't related to the nodes directly, but to a
traversersal of the scene graph that compares the bounding
shere's of internal nodes of the scene graph and the
bounding boxes of the drawable leaves.  Culling can happen
at any point in the hierarchy - it can cull right up at the
top node in the scene graph if the scene is outside the view
frustum.
  
  
  Within the cull traversal there is no tracking of culled
or non culling bounding boxes, a cull test is done and the
bool result used directly.  There isn't a "bounding box" or
"bounding sphere" for culled or non culled objects.  All the
cull traversal cares about is building a list of drawables
leaves that pass the view frustum test, there is no tracking
of any objects that are culled - this would be a crazy waste
of CPU resources.
  
  
  
  I have to ask, why do you want a bounding box of culled
objects - what is the high level problem you are trying to
solve?  It may well be that you are asking the wrong
question thinking about the task you have in the wrong way.
  
  
  
  Robert.
  

  


thanks for pointing out how cull traversal operates.

Yes, it might be I am searching in the wrong direction. I need to
get the minimum and the maximum Z coordinate of the geometry
vertices in order to apply a color range. This is quite easy to do
for the whole geometry but I would know if there is a way just for
the vertices inside the view frustum.

Regards,
Renzo

  




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Re: [osg-users] bounding box of culled geometry

[OpenSceneGraph Users]

Hi Renzo,

On Wed, 14 Oct 2020 at 12:00, OpenSceneGraph Users <
osg-users@lists.openscenegraph.org> wrote:

> I am using osg::Drawable::getBoundingBox() to retrieve the bounding box
> around the whole geometry. Is there a similar short way to get the
> equivalent box for just the culled geometry or do I need to write my own
> procedure?
>

Culling isn't related to the nodes directly, but to a traversersal of the
scene graph that compares the bounding shere's of internal nodes of the
scene graph and the bounding boxes of the drawable leaves.  Culling can
happen at any point in the hierarchy - it can cull right up at the top node
in the scene graph if the scene is outside the view frustum.

Within the cull traversal there is no tracking of culled or non culling
bounding boxes, a cull test is done and the bool result used directly.
There isn't a "bounding box" or "bounding sphere" for culled or non culled
objects.  All the cull traversal cares about is building a list of
drawables leaves that pass the view frustum test, there is no tracking of
any objects that are culled - this would be a crazy waste of CPU resources.

I have to ask, why do you want a bounding box of culled objects - what is
the high level problem you are trying to solve?  It may well be that you
are asking the wrong question thinking about the task you have in the wrong
way.

Robert.

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