Ideally I'd be doing it on the CPU, but the particular objects I'm picking are skinned meshes drawn in a 3rd party library, so I don't think there's any reasonable way to do that, since the vertex positions aren't known on the CPU.
Max On Fri, Sep 27, 2013 at 2:00 PM, Robert Osfield <[email protected]>wrote: > Hi Max, > > I would not recommend trying to to use rendering to do picking, it > requires a round trip to the graphics card making it a very slow way to do > picking. If you can do picking on the CPU. > > Robert. > > > On 27 September 2013 17:34, Max Bandazian <[email protected]> wrote: > >> Hi, >> >> I'm trying to implement picking via rendering a single frame with unique >> colors set on each object in the scene, and getting segfaults in the >> graphics driver. I'm about out of debugging ideas, so any help would be >> appreciated. The general outline is I create a viewer, give it a shared >> context, set it to render to an FBO and add an image, and render one frame, >> at which point it immediately segfaults. >> >> When I run this in gDEBugger, I can see that there are textures allocated >> in the shared context, but none of them have any data; this is probably >> what's causing the crash, but since the corresponding textures in the main >> context do have data, I'm not sure what the problem is. Source is below, >> simplified a little for readability; hopefully I'm just doing something >> dumb and easily spotted. >> >> Thanks, >> Max Bandazian >> >> >> osg::Image* image = new osg::Image; >> { >> mainViewer->stopThreading(); >> >> osg::GraphicsContext* mainContext = >> mainViewer->getCamera()->getGraphicsContext(); >> osg::ref_ptr<osg::GraphicsContext::Traits> traits = new >> osg::GraphicsContext::Traits; >> traits->doubleBuffer = false; >> traits->vsync = false; >> traits->x = 0; >> traits->y = 0; >> traits->width = widthPx; >> traits->height = heightPx; >> traits->windowDecoration = false; >> traits->pbuffer = true; >> traits->red = 8; >> traits->green = 8; >> traits->blue = 8; >> traits->alpha = 8; >> traits->depth = 24; >> traits->sharedContext = mainContext; >> >> osg::ref_ptr<osg::GraphicsContext> pickContext = >> osg::GraphicsContext::createGraphicsContext(traits.get()); >> >> >> osg::Texture2D* tex = new osg::Texture2D; >> tex->setTextureSize(PICK_TEXTURE_DIMENSION, PICK_TEXTURE_DIMENSION); >> >> // Set up the viewer >> osg::ref_ptr<osgViewer::Viewer> pickView = new osgViewer::Viewer(); >> pickView->setThreadingModel(osgViewer::ViewerBase::SingleThreaded); >> >> osg::Camera* pickCamera = pickView->getCamera(); >> pickCamera->setGraphicsContext(pickContext.get()); >> >> pickCamera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT); >> >> pickCamera->setProjectionMatrix(sceneCamera->getProjectionMatrix()); >> pickCamera->setViewport(0, 0, PICK_TEXTURE_DIMENSION, >> PICK_TEXTURE_DIMENSION); >> >> pickCamera->setClearColor(osg::Vec4(0.0f, 0.0f, 0.0f, 1.0f)); >> pickCamera->setClearMask( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT >> ); >> >> osg::Shader* vs = new osg::Shader(osg::Shader::VERTEX); >> vs->loadShaderSourceFromFile("pick_shader.vert"); >> osg::Shader* fs = new osg::Shader(osg::Shader::FRAGMENT); >> fs->loadShaderSourceFromFile("pick_shader.frag"); >> >> osg::Program* program = new osg::Program; >> program->addBindAttribLocation("attr_weight_array", >> osg::Drawable::ATTRIBUTE_6); >> program->addBindAttribLocation("attr_index_array", >> osg::Drawable::ATTRIBUTE_7); >> program->addBindAttribLocation("attr_tangent", >> osg::Drawable::SECONDARY_COLORS); >> program->addShader(vs); >> program->addShader(fs); >> >> pickView->setSceneData(skinnedMeshRoot); >> >> pickCamera->getOrCreateStateSet()->setAttributeAndModes(program, >> osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE); >> >> osg::ShadeModel* sm = new osg::ShadeModel(osg::ShadeModel::FLAT); >> pickCamera->getOrCreateStateSet()->setAttributeAndModes(sm, >> osg::StateAttribute::ON | osg::StateAttribute::OVERRIDE); >> >> // attach an image to the view >> image->allocateImage(PICK_TEXTURE_DIMENSION, >> PICK_TEXTURE_DIMENSION, 1, GL_RGBA, GL_UNSIGNED_BYTE); >> pickCamera->attach(osg::Camera::COLOR_BUFFER, image); >> >> // finalize and render >> pickView->realize(); >> pickView->setCameraManipulator(0); >> pickView->frame(); >> } >> mainViewer()->startThreading(); >> >> return image; >> >> _______________________________________________ >> 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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