Hello,
I tried this in my camera draw callback:
virtual void operator()(const osg::Camera& camera) const
{
// GL-Context-ID
GLuint gcID = _gc->getState()->getContextID();
// GL-Program-Handle
osg::Program::PerContextProgram* pcp = _program->getPCP(gcID);
GLuint prID=pcp->getHandle();
const char* varyings[1] = { "vPosition" };
glTransformFeedbackVaryings(prID, 1, varyings, GL_SEPARATE_ATTRIBS);
}
But when I want to compile this, I get the error "glTransformFeedbackVaryings
isn't defined". I searched in my includes and it is in the glext.h and glew.h
defined. What is wrong?
Cheers,
Martin
-------- Original-Nachricht --------
> Datum: Tue, 28 Feb 2012 10:45:16 -0700
> Von: Paul Martz <[email protected]>
> An: OpenSceneGraph Users <[email protected]>
> Betreff: Re: [osg-users] GL_TRANSFORM_FEEDBACK_BUFFER_NV in OSG
> On 2/28/2012 9:10 AM, "Martin Großer" wrote:
> > Hello Paul,
> >
> > In OpenGL I have to define the varying variables for the transform
> feedback between the compiling and linking of the shader program.
> >
> > glTransformFeedbackVaryings(programHandle, 1, varyings,
> GL_SEPARATE_ATTRIBS);
> >
> > How can I do this in OSG?
>
> The same way. You can issue an OpenGL call any time you have a current
> context
> (Camera pre draw callback, Drawable draw callback, etc).
>
> A quick glance at the Program header file reveals that you can get the
> program
> ID with a call to:
> osg::Program::getPCP(contextID)->getHandle();
>
> > Additinally I use osg 2.8.4 from the Fedora repository.
> >
> > Cheers,
> > Martin
> >
> > -------- Original-Nachricht --------
> >> Datum: Mon, 27 Feb 2012 09:51:15 -0700
> >> Von: Paul Martz<[email protected]>
> >> An: OpenSceneGraph Users<[email protected]>
> >> Betreff: Re: [osg-users] GL_TRANSFORM_FEEDBACK_BUFFER_NV in OSG
> >
> >> Yes, it's possible, but there are no examples that I know of. You might
> >> try
> >> binding a buffer object in a Camera pre-draw callback, for an example
> of
> >> one
> >> strategy.
> >> -Paul
> >>
> >>
> >> On 2/27/2012 8:21 AM, "Martin Großer" wrote:
> >>> Hello,
> >>>
> >>> Is it possible to use GL_TRANSFORM_FEEDBACK_BUFFER_NV extension in
> osg?
> >> I would like write back my vertex position data into a new Vertex
> Buffer
> >> Object. Is there any example about this?
> >>>
> >>> Cheers
> >>>
> >>> Martin
> >> _______________________________________________
> >> osg-users mailing list
> >> [email protected]
> >>
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
> >
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