Hi Robert, I am sorry for not providing an adequate description.
High level explanation of what I am trying to do: Replace some of the geometry in the scene with live camera feed. But in order to do this, I still need the actual geometry in the scene to modify the depth buffer as if it were there even though it is not visible. The initial set up for the render states of the scene is: osgUtil::CullVisitor *pCullVisitor = m_sceneView->getCullVisitor(); osgUtil::RenderBin *pRenderBin = pCullVisitor->getCurrentRenderBin(); pRenderBin->setSortMode(osgUtil::RenderBin::SORT_BACK_TO_FRONT); osg::StateSet *pStateSet = m_sceneView->getGlobalStateSet(); pStateSet->setMode(GL_ALPHA_TEST,osg::StateAttribute::OFF); osg::CullFace *pCullFace = new osg::CullFace; pCullFace->setMode(osg::CullFace::BACK); pStateSet->setMode(GL_CULL_FACE, osg::StateAttribute::ON); pStateSet->setAttribute(pCullFace, osg::StateAttribute::ON); osg::ShadeModel *pShadeMdl = new osg::ShadeModel; pShadeMdl->setMode(osg::ShadeModel::FLAT); pStateSet->setAttribute(pShadeMdl, osg::StateAttribute::ON); osg::Depth *pDepth = new osg::Depth; pDepth->setFunction(osg::Depth::LEQUAL); pStateSet->setMode(GL_DEPTH_TEST, osg::StateAttribute::ON); pStateSet->setAttribute(pDepth, osg::StateAttribute::ON); All I do to make some of the geometry not visible and yet still drawn to the depth buffer, is disable writes to the color buffer: osg::ColorMask *colormaskOff = new osg::ColorMask(false, false, false, false); osg::StateSet* state = node->getOrCreateStateSet(); state->setAttribute(colormaskOff); At another point in the scene graph, I enable writes to the color buffer using the same method except the ColorMask values are all true. I never disable depth testing. When the scene is rendered, I see my video background and I see my objects that should be visible. However, the depth buffer testing does not seem to work correctly because some parts of the visible geometry that should be occluded by the invisible geometry are showing. But this is not uniform. There are times when the visible geometry is occluded by the invisible geometry as it should be. If I change the sorting to this: pRenderBin->setSortMode(osgUtil::RenderBin::SORT_FRONT_TO_BACK); then it appears to work until I rotate the camera and then there are angles which seem to break the depth testing. What doesn't make sense to me is why the behavior should change at all just by disabling writes to the color buffer? I have done the same with OpenGL code in a different application, where I was not sorting (because there was no transparency) and just relying on the graphics drivers\hardware to do the Z buffering, and the occlusion of the inivisible objects worked fine. So it seems there must be some "optimization" taking place inside the scene graph that is culling objects or something. I don't know. It just doesn't make sense to me why I can do something in OpenGL and not with OSG. What do you think? Thanks, Judie On Apr 16, 1:57 am, "Robert Osfield" <[EMAIL PROTECTED]> wrote: > Hi Judie, > > I'm afraid I've just found it too difficult to work out what you are > doing to be able to provide any suggestions. Could you provide a high > level explanation of what you are trying to do and why to give a bit > of context. Then why you provide code snippets could you space them > better as word wrap has made it extremely difficult to read the code. > > Robert. > > > > > > On Tue, Apr 15, 2008 at 11:09 PM, Judie <[EMAIL PROTECTED]> wrote: > > In my code I have an OSG tree with the following global state > > attributes defined: > > > osgUtil::CullVisitor *pCullVisitor = m_sceneView- > > >getCullVisitor(); > > osgUtil::RenderBin *pRenderBin = > > pCullVisitor->getCurrentRenderBin(); > > pRenderBin->setSortMode(osgUtil::RenderBin::SORT_BACK_TO_FRONT); > > osg::StateSet *pStateSet = m_sceneView- > > >getGlobalStateSet(); > > pStateSet->setMode(GL_ALPHA_TEST, > > osg::StateAttribute::OFF); > > osg::CullFace *pCullFace = new osg::CullFace; > > pCullFace->setMode(osg::CullFace::BACK); > > pStateSet->setMode(GL_CULL_FACE, osg::StateAttribute::ON); > > pStateSet->setAttribute(pCullFace, osg::StateAttribute::ON); > > osg::ShadeModel *pShadeMdl = new osg::ShadeModel; > > pShadeMdl->setMode(osg::ShadeModel::FLAT); > > pStateSet->setAttribute(pShadeMdl, osg::StateAttribute::ON); > > osg::Depth *pDepth = new osg::Depth; > > pDepth->setFunction(osg::Depth::LEQUAL); > > pStateSet->setMode(GL_DEPTH_TEST, osg::StateAttribute::ON); > > pStateSet->setAttribute(pDepth, osg::StateAttribute::ON); > > > The only other time I change the state is when I enable and disable > > the color buffer writes. > > > Here is what I am seeing: > > If I render the scene with the color buffer always on, then objects > > that should be occluded by other objects behave correctly and are > > occluded. > > > When I render the scene with the color buffer off for some of the > > nodes in the beginning of the tree, with it enabled again for ones > > later on, I expect that because I DID NOT disable writes to the depth > > buffer, that the objects which are occluded by other objects (even > > though they were not drawn to the color buffer) should behave > > correctly. However, they do not. Some do and some don't and if I > > rotate then even ones that behave correctly, begin to misbehave. > > > Now I have made the following change because I don't need to worry > > about transparency anymore: > > pRenderBin->setSortMode(osgUtil::RenderBin::SORT_FRONT_TO_BACK); > > > And this almost fixes the issue except if I rotate to some degree, I > > still get parts of objects drawn that should be occluded. I know > > because I can toggle the objects visible and invisible. > > > Is there something internally that can be culling parts of objects > > because I have the color buffer masked for them? > > > Thanks, > > > Judie > > _______________________________________________ > > osg-users mailing list > > [EMAIL PROTECTED] > > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph... > > _______________________________________________ > osg-users mailing list > [EMAIL > PROTECTED]://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph...- > Hide quoted text - > > - Show quoted text - _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
