Generally you should use interfaces provided by osg to get to opengl functions, as they can have different pointers in different graphics contexts.
so it goes like typedef void (APIENTRY * TransformFeedbackVaryings)(GLuint, GLsizei, const GLchar **, GLenum); TransformFeedbackVaryings _glTransformFeedbackVaryingsPtr; if (!osg::setGLExtensionFuncPtr(_glTransformFeedbackVaryingsPtr, "glTransformFeedbackVaryings" )) if (!osg::setGLExtensionFuncPtr(_glTransformFeedbackVaryingsPtr, "glTransformFeedbackVaryingsEXT" )) //not supported :( // so now you can use this pointer in this gc also if you need some opengl functions, first check osg::GL2Extensions, it may be already wrapped and initialized there. All of this should be called with active graphics context Cheers 29.02.2012, 18:22, "Martin Groer" <[email protected]>: > 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 >> _______________________________________________ >> osg-users mailing list >> [email protected] >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > -- > NEU: FreePhone 3-fach-Flat mit kostenlosem Smartphone! > Jetzt informieren: http://mobile.1und1.de/?ac=OM.PW.PW003K20328T7073a > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
