Hi, Martin iirc i've used full gl style as i cant make it work with just osg default drawimplementation + state management (like program and modes) atm (i mean i tried for a week or two and it just wasnt working, and this stuff really hard to debug when it draws crap or crashes in driver, i dont remember details as it was like two years ago or so) You can try, may be you got some luck. I think it is possible to do this with osg program and buffer objects management, then things get a lot simplier as you dont need to initialize all stuff yourself. and this was just first more or less working sample (still no multiple context safe, and may be have some other bugs), things changed quite a bit since then
also with gl 4.2 you can drop queries, as you have drawTransformFeedback, but then you cant use osg draw implementation As for guides for embedding gl into osg... i dont saw any. You can dig into osg::Geometry\StateAttributes\osg::State sources to see how it done in osg itself. From my experience i can say that if you make gl state changes via gl functions yourself you should let osg know about them(check osg::State reference). If something not working try to revert all state changes you've done after your drawing (unbind buffers\arrays, revert fbo bindings, active texture units, vertex attrib arrays, programs, etc...) 01.03.2012, 20:46, "Martin Groer" <grosser.mar...@gmx.de>: > Hello Sergey, > > thank you, it is good to know. I am a little bit frustrated. I read about > OpenGL 4.2 and transform feedback and was so happy about this. That sounds so > easy to use. By now it is hard to implement a simple first example. :-( > > I found this thread: > http://www.mail-archive.com/osg-users@lists.openscenegraph.org/msg46962.html > > You made this example, right? So far, I don't understand all the stuff. Is > this all necessary for transform feedback? > > I only need the follow functions, don't I? > > 1. glTransformFeedbackVaryings > 2. glBindBufferBase > 3. glBeginTransformFeedback > 4. glEndTransformFeedback > > For example, is a loadShaderFromFile function necessary? Is this only > necessary, because the glTransformFeedbackVaryings have to be between the > compiling and linking of the shader? > > I think my first problem is I don't have any experience with OpenGL code > embedded into osg code. Are there any examples, tutorials or articles about > this? > > I will keep on trying! > > Cheers, > Martin > > -------- Original-Nachricht -------- > >> Datum: Thu, 01 Mar 2012 19:34:42 +0400 >> Von: Sergey Polischuk <pol...@yandex.ru> >> An: OpenSceneGraph Users <osg-users@lists.openscenegraph.org> >> Betreff: Re: [osg-users] GL_TRANSFORM_FEEDBACK_BUFFER_NV in OSG >> 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" <grosser.mar...@gmx.de>: >>> 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 <pma...@skew-matrix.com> >>>> An: OpenSceneGraph Users <osg-users@lists.openscenegraph.org> >>>> 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<pma...@skew-matrix.com> >>>>>> An: OpenSceneGraph Users<osg-users@lists.openscenegraph.org> >>>>>> 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 >>>>>> osg-users@lists.openscenegraph.org >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >>>> _______________________________________________ >>>> osg-users mailing list >>>> osg-users@lists.openscenegraph.org >> 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 >>> osg-users@lists.openscenegraph.org >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >> _______________________________________________ >> osg-users mailing list >> osg-users@lists.openscenegraph.org >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > -- > Empfehlen Sie GMX DSL Ihren Freunden und Bekannten und wir > belohnen Sie mit bis zu 50,- Euro! https://freundschaftswerbung.gmx.de > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
