Hi Robert, Thanks for reply.
Actually, i have attached osg::light to lightSource node. What makes me confused is why different results comes up when using the two ways of attaching light to lightSource node: first one: using setLight method > osg::LightSource* ls = new osg::LightSource; > ls->setLight(new osg::Light(0)); The other one: using setAttribute osg::LightSource* ls = new osg::LightSource; ls->getOrCreateStateSet()->setAttribute(new osg::Light(0)); Rogerz 2010-08-30 发件人： Robert Osfield 发送时间： 2010-08-30 16:19:08 收件人： OpenSceneGraph Users 抄送： 主题： Re: [osg-users] what's the difference between these two ways ofdefining light? Hi Rogerz? The OSG has to binding positional state like glLight/osg::Light with a modelview matrix to position it correctly in space, which is why there is a special node in the scene graph for positioning it - the osg::LightSource node. If you don't attach your osg::Light to this special node then the light will be applied at an arbitrary point with an arbitrary modelview matrix that is current when it's applied - the result will be undefined, there is nothing the OSG can do about this - which is why the LightSource node exists - so use it. Robert. On Mon, Aug 30, 2010 at 4:25 AM, myth0904 <[email protected]> wrote: > I wanna add a head light into the scene, ie.,the light is always attched > with camera. > > For adding a light source into the scene, there are two different ways as i > know: > > 1 using osg::LightSource:: setLight method > > > osg::LightSource* ls = new osg::LightSource; > ls->setLight(new osg::Light(0)); > ls->setReferenceFrame(osg::LightSource::ABSOLUTE_RF); > geode->setStateSet(ls->getOrCreateStateSet()); > > > 2 using setAttribute method > > ls->getOrCreateStateSet()->setAttribute(new osg::Light(0)); > geode->setStateSet(ls->getOrCreateStateSet()); > > > I think two different ways should give the same result. Actually, they are > different. > > No. 1 Method: the light behaves like directional light, but not head light. > > No.2 method: just like head light. > > > who could tell me why the two ways are different? > which is correct? > > > > ________________________________ > Rogerz > 2010-08-30 > _______________________________________________ > 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
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