Hi Robert, Thank you very much for your very detailed help!!! osgFX is exactly what I was looking for. Actually I don't even need the camera, I only put it there to be able to assign the post-draw callback.
I will try it and if it works, I will post the code, just in case someone is interested... Best regards! On Thu, Sep 2, 2010 at 5:19 PM, Robert Milharcic < [email protected]> wrote: > > > You can use osgFX node kit framework to implement described capping > tehnique. You do that by inheriting osgFX::Effect class. In your derived > class you have to override/implement virtual bool define_techniques() > member of the osgFX::Effect class like this: > > > > bool CappingEffect::define_techniques() > > { > > CappingTechnique* technique = new CappingTechnique(this); > > addTechnique(technique); > > return true; > > } > > > > CappingTechnique must inherit from osgFX::Technique. In the derived class > you will have to implement virtual bool validate(osg::State&) const, > virtual void define_passes() and optionally virtual osg::Node* > getOverrideChild(int pass) like this: > > > > bool CappingTechnique::validate(osg::State&) const > > { > > return true; > > } > > > > bool CappingTechnique:: define_passes() > > { > > // pass #1 > > { > > osg::ref_ptr<osg::StateSet> ss = new osg::StateSet; > > ... setup states for stencil operation > > addPass(ss.get()); > > } > > // implement pass #2 > > { > > osg::ref_ptr<osg::StateSet> ss = new osg::StateSet; > > ... setup states for solid color draw > > addPass(ss.get()); > > } > > } > > > > You can optionally implement getOverrideChild (int pass) to supply some > other graph for a particlular pass. You then add your group to the > CappingEffect (the osgFX::Effect inherits from osg::Group node) and > CappingEffect to the camera. > > > > Robert Milharcic > > > > *From:* [email protected] [mailto: > [email protected]] *On Behalf Of *Javier Taibo > *Sent:* Thursday, September 02, 2010 1:09 PM > *To:* [email protected] > *Subject:* [osg-users] draw callbacks > > > > Hi, > > I have some solid geometry clipped by some clipping planes in an OSG > application. I am trying to use the capping technique described in chapter > 10 of the Red Book using the stencil buffer. I have successfully implemented > this technique in raw OpenGL, but I would like to use it whithin the OSG > application. The technique is based on storing on the stencil buffer the > regions that are "open" and then in a later pass draw a solid color in these > regions. > > I have put the clipped geometry under an osg::Camera node with the > stencil function configured. To do the second pass (the one that draws the > caps in the regions marked in the stencil), I am trying to use a post-draw > callback with the OpenGL calls (saving and restoring the states to avoid > breaking things). The problem is that I need to set the NESTED rendering > order to see all the scene graph, and when I do it, the post-draw callback > is not called anymore. > > I do not have full control over the application, so the solution I am > looking for has to be "transparent" to the rest of the scene graph. I must > activate this behaviour to a group in the scene graph without breaking > anything outside this branch. What is the best way to do it? camera > post-draw callbacks? rendering bins? any other? > > I am not very familiar with render passes in OSG, so the way I am trying > is probably not the best way. I would appreciate any suggestion, advice or > pointer to any related documentation or source code. > > > Thanks in advance. > > > Javier Taibo. > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > >
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