Re: [osg-users] Perform actions when a child node is added

[Robert Osfield]

On 26 June 2017 at 13:18, Bruno Oliveira
 wrote:
> a dangling pointer is a probable cause of my problems. Thanks for the hint,
> I'll look into it.
>
> I thought it could be related to me rewriting the node's InitialBound.

Modify and reading data like Node::_initialBound on a valid Node would
only cause problems with things like culling or positioning
incorrectly it is very unlikely to cause a crash.

Trying to write to a Node::_initialBound to a node that has been
deleted will cause very likely crash, if it doesn't crash it's only a
fluke that that freed memory hasn't been reused yet.

Robert.
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Re: [osg-users] Perform actions when a child node is added

[Bruno Oliveira]

Robert,

a dangling pointer is a probable cause of my problems. Thanks for the hint,
I'll look into it.

I thought it could be related to me rewriting the node's InitialBound.

Thanks,
Bruno

2017-06-26 10:15 GMT+01:00 Robert Osfield :

> Hi Bruno,
>
> On 23 June 2017 at 23:45, Bruno Oliveira
>  wrote:
> > I actually tried it already, in my nodes derived doth from osg::Group*
> and
> > osg::PagedLOD*.
> > However, overloading the PagedLOD's functions made my scene crash the app
> > during the cull traversal (my overload was rewriting the node's center,
> > radius and InitialBound...)
>
> If you've got a crash it'll likely be because what you are doing
> somewhere is buggy, perhaps an assumption somewhere.  Overriding
> addChild/insertChild() won't cause a crash if done properly.
>
> In the case of paged databases nodes are added and removed, the later
> can cause problems such as if your code just uses C pointers to these
> nodes assuming that they'll always be around.
>
> I can't say what might have caused the crash for you as I know nothing
> about the code you've written or what the crash is, or exactly what
> circumstances it happens in.
>
> You'll have a debugger, your have your code, your data, you're the
> person best placed to debug it.
>
> Robert.
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Re: [osg-users] Perform actions when a child node is added

[Robert Osfield]

Hi Bruno,

On 23 June 2017 at 23:45, Bruno Oliveira
 wrote:
> I actually tried it already, in my nodes derived doth from osg::Group* and
> osg::PagedLOD*.
> However, overloading the PagedLOD's functions made my scene crash the app
> during the cull traversal (my overload was rewriting the node's center,
> radius and InitialBound...)

If you've got a crash it'll likely be because what you are doing
somewhere is buggy, perhaps an assumption somewhere.  Overriding
addChild/insertChild() won't cause a crash if done properly.

In the case of paged databases nodes are added and removed, the later
can cause problems such as if your code just uses C pointers to these
nodes assuming that they'll always be around.

I can't say what might have caused the crash for you as I know nothing
about the code you've written or what the crash is, or exactly what
circumstances it happens in.

You'll have a debugger, your have your code, your data, you're the
person best placed to debug it.

Robert.
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Re: [osg-users] Perform actions when a child node is added

[Trajce Nikolov NICK]

Hi Bruno,

What Robert suggested is the correct one. However, I was in your situation
where I had to do stuff on PagedLOD children change so I end up with a
working hack, and that was an Update callback monitoring the children. Just
an idea

On Sat, Jun 24, 2017 at 12:45 AM, Bruno Oliveira <
bruno.manata.olive...@gmail.com> wrote:

> I actually tried it already, in my nodes derived doth from osg::Group* and
> osg::PagedLOD*.
> However, overloading the PagedLOD's functions made my scene crash the app
> during the cull traversal (my overload was rewriting the node's center,
> radius and InitialBound...)
>
> 2017-06-23 15:18 GMT+01:00 Robert Osfield :
>
>> HI Bruno,
>>
>> There is no "child added callback" mechanism in osg::Group, but you
>> can override the addChild and insertChild methods to catch attempts to
>> add children, deferring the implementation to the underlying
>> addChild/insertChild method and then doing what extra's you want,
>>
>> Robert.
>>
>> On 23 June 2017 at 11:31, Bruno Oliveira
>>  wrote:
>> > Hello,
>> >
>> >
>> > I want to be able to perform some actions inside a node of my own, when
>> > someone adds a child node to it.
>> >
>> > Is this possible via some callback mechanism or so?
>> >
>> >
>> > --
>> >
>> > Also, another question. Using osgDB::Registry::ReadFileCallback, I can
>> only
>> > perform actions after a node is read and before it is added to me
>> scene. Is
>> > it possible to perform actions AFTER the node is read and added to the
>> > scene?
>> >
>> >
>> > Thanks.
>> >
>> > ___
>> > osg-users mailing list
>> > osg-users@lists.openscenegraph.org
>> > http://lists.openscenegraph.org/listinfo.cgi/osg-users-opens
>> cenegraph.org
>> >
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>
>
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>


-- 
trajce nikolov nick
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Re: [osg-users] Perform actions when a child node is added

[Bruno Oliveira]

I actually tried it already, in my nodes derived doth from osg::Group* and
osg::PagedLOD*.
However, overloading the PagedLOD's functions made my scene crash the app
during the cull traversal (my overload was rewriting the node's center,
radius and InitialBound...)

2017-06-23 15:18 GMT+01:00 Robert Osfield :

> HI Bruno,
>
> There is no "child added callback" mechanism in osg::Group, but you
> can override the addChild and insertChild methods to catch attempts to
> add children, deferring the implementation to the underlying
> addChild/insertChild method and then doing what extra's you want,
>
> Robert.
>
> On 23 June 2017 at 11:31, Bruno Oliveira
>  wrote:
> > Hello,
> >
> >
> > I want to be able to perform some actions inside a node of my own, when
> > someone adds a child node to it.
> >
> > Is this possible via some callback mechanism or so?
> >
> >
> > --
> >
> > Also, another question. Using osgDB::Registry::ReadFileCallback, I can
> only
> > perform actions after a node is read and before it is added to me scene.
> Is
> > it possible to perform actions AFTER the node is read and added to the
> > scene?
> >
> >
> > Thanks.
> >
> > ___
> > 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] Perform actions when a child node is added

[Robert Osfield]

HI Bruno,

There is no "child added callback" mechanism in osg::Group, but you
can override the addChild and insertChild methods to catch attempts to
add children, deferring the implementation to the underlying
addChild/insertChild method and then doing what extra's you want,

Robert.

On 23 June 2017 at 11:31, Bruno Oliveira
 wrote:
> Hello,
>
>
> I want to be able to perform some actions inside a node of my own, when
> someone adds a child node to it.
>
> Is this possible via some callback mechanism or so?
>
>
> --
>
> Also, another question. Using osgDB::Registry::ReadFileCallback, I can only
> perform actions after a node is read and before it is added to me scene. Is
> it possible to perform actions AFTER the node is read and added to the
> scene?
>
>
> Thanks.
>
> ___
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> osg-users@lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>
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