Re: [osg-users] DrawCallback only once
Hi Dominc,
The best way to do a single GL test at startup is to attach a custom
osg::GraphicsOperation as a RealizeOperation to the viewer, and this
gets called once the viewer's graphics contexts get realized.
Have a look at the osgcatch, osgshaderterrrain and osgvolume examples
to see examples of the above in action.
Robert.
On Fri, Jan 8, 2010 at 8:50 PM, Dominic Stalder
dominic.stal...@bluewin.ch wrote:
Hi there
I would like to read the OpenGL extensions with isGLExtensionSupported(),
but for this I need a draw context. I registred a DrawCallback Class, see
below. I need to call the operator() method only once, but because this
method is const, I cannot write to the member variable bool first. How can I
resolve this problem?
class GameViewOSGDrawCallback : public osg::Camera::DrawCallback
{
private:
GameViewOSG *parent;
bool first;
public:
GameViewOSGDrawCallback(GameViewOSG* parent=0);
virtual void operator()(const osg::Camera) const;
};
Thanks a lot
Dominic
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Re: [osg-users] DrawCallback only once
Hi Robert thanks a lot, at the moment it works fine the way I made it. But I will try this solution as soon as possible. Am 11.01.10 11:41, schrieb Robert Osfield: The best way to do a single GL test at startup is to attach a custom osg::GraphicsOperation as a RealizeOperation to the viewer, and this gets called once the viewer's graphics contexts get realized. Have a look at the osgcatch, osgshaderterrrain and osgvolume examples to see examples of the above in action. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] DrawCallback only once
Hi Dj and Tim
thanks for the answers, I made a little hack, but it works for me ;-) In
the operator() method I just set the pre draw callback of the camera to
zero, so the method never gets called again later.
void GameViewOSG::GameViewOSGDrawCallback::operator()(const Camera) const
{
parent-osgCamera-setPreDrawCallback(NULL);
}
Regards
Dominic
Am 09.01.10 00:55, schrieb Tim Moore:
On Fri, Jan 8, 2010 at 9:50 PM, Dominic Stalder
dominic.stal...@bluewin.ch mailto:dominic.stal...@bluewin.ch wrote:
Hi there
I would like to read the OpenGL extensions with
isGLExtensionSupported(), but for this I need a draw context. I
registred a DrawCallback Class, see below. I need to call the
operator() method only once, but because this method is const, I
cannot write to the member variable bool first. How can I resolve
this problem?
class GameViewOSGDrawCallback : public
osg::Camera::DrawCallback
{
private:
GameViewOSG *parent;
bool first;
public:
GameViewOSGDrawCallback(GameViewOSG* parent=0);
virtual void operator()(const osg::Camera) const;
};
You might look at using an Operation on the graphics context, which
has a one-shot mode that is more convenient and efficient than a
boolean in a callback. Take a look at the Operation class in
osg/OperationThread and osg::GraphicsContext::add(Operation*).
Tim
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[osg-users] DrawCallback only once
Hi there
I would like to read the OpenGL extensions with
isGLExtensionSupported(), but for this I need a draw context. I
registred a DrawCallback Class, see below. I need to call the operator()
method only once, but because this method is const, I cannot write to
the member variable bool first. How can I resolve this problem?
class GameViewOSGDrawCallback : public osg::Camera::DrawCallback
{
private:
GameViewOSG *parent;
bool first;
public:
GameViewOSGDrawCallback(GameViewOSG* parent=0);
virtual void operator()(const osg::Camera) const;
};
Thanks a lot
Dominic
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Re: [osg-users] DrawCallback only once
Hi, Dominic.
I'm not sure this method is the best option for what you want, but I
don't have any ready alternatives myself, so I'll just answer your
question and move on.
I would recommend reading the following FAQ:
http://www.parashift.com/c++-faq-lite/const-correctness.html
In that context, I might recommend changing your declaration:
// begin code
bool first;
// end code
to this:
// begin code
mutable bool first;
// end code
In the event that your compiler doesn't support keyword mutable, you
can fake it with a member pointer that you have to initialize in your
constructor and cleanup in your destructor, but that is a little
clunky, and I would avoid it if I could. You would change this:
// begin code
bool first;
// end code
to this:
// begin code
bool* first;
// end code
and then do the appropriate initialization and cleanup.
I hope this helps...
D.J.
On Fri, Jan 8, 2010 at 3:50 PM, Dominic Stalder
dominic.stal...@bluewin.ch wrote:
Hi there
I would like to read the OpenGL extensions with isGLExtensionSupported(),
but for this I need a draw context. I registred a DrawCallback Class, see
below. I need to call the operator() method only once, but because this
method is const, I cannot write to the member variable bool first. How can I
resolve this problem?
class GameViewOSGDrawCallback : public osg::Camera::DrawCallback
{
private:
GameViewOSG *parent;
bool first;
public:
GameViewOSGDrawCallback(GameViewOSG* parent=0);
virtual void operator()(const osg::Camera) const;
};
Thanks a lot
Dominic
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Re: [osg-users] DrawCallback only once
On Fri, Jan 8, 2010 at 9:50 PM, Dominic Stalder
dominic.stal...@bluewin.chwrote:
Hi there
I would like to read the OpenGL extensions with isGLExtensionSupported(),
but for this I need a draw context. I registred a DrawCallback Class, see
below. I need to call the operator() method only once, but because this
method is const, I cannot write to the member variable bool first. How can I
resolve this problem?
class GameViewOSGDrawCallback : public osg::Camera::DrawCallback
{
private:
GameViewOSG *parent;
bool first;
public:
GameViewOSGDrawCallback(GameViewOSG* parent=0);
virtual void operator()(const osg::Camera) const;
};
You might look at using an Operation on the graphics context, which has a
one-shot mode that is more convenient and efficient than a boolean in a
callback. Take a look at the Operation class in osg/OperationThread and
osg::GraphicsContext::add(Operation*).
Tim
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