It sounds like you are trying to draw a 2D element at the same window position as a 3D object. Is this correct?
If you are going to project all the way to window coordinates, then you'll need to configure your projection matrix to render in window coordinates. You'd need two Camera nodes for this, one with your 3D projection and one for 2D. Another approach would be to just project down to eye coordinates (instead of all the way to window coordinates) and continue to use the same projection matrix. The disadvantage of this approach is that your 2D rendering would not be in Window coordinates. To code tasks like these proficiently, you would be well-advised to familiarize yourself with the OpenGL transformation pipeline. From your posts, it seems apparent that you don't have a good mastery of this topic. Get the OpenGL red book. Paul Martz Skew Matrix Software LLC http://www.skew-matrix.com +1 303 859 9466 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Hagen Sent: Tuesday, April 21, 2009 2:56 AM To: [email protected] Subject: Re: [osg-users] 3D Point to ScreenSpace Coordinates Thank you for those two answers. I forgot to say the point is in world coordinates so the first transformation should be obsolete for me. Then I did the following very simple where POSITION is the vector of the point and ssc is the result. Code: osg::Camera* cam = this->viewer->getCamera(); osg::Matrix viewMatrix = cam->getViewMatrix(); osg::Matrix projectionMatrix = cam->getProjectionMatrix(); osg::Matrix windowMatrix = cam->getViewport()->computeWindowMatrix(); osg::Matrix cameraMatrix = viewMatrix * projectionMatrix * windowMatrix; osg::Vec3 ssc = POSITION*cameraMatrix; pos->setPosition(osg::Vec3(ssc.x(),ssc.y(),0)); As you can see I give the the result to PositionAttitudeTransform. This PAT is attached to a slave cam with ABSOLUTE_RF This way I can have HUD (2D) elements following nodes in 3d. Problem: The accuracy is not very well. Moving th camera my HUD element is never exactly where it i supposed to be but just somwhere around the supposed area. Could that be float and double problems? If so: How can I make OSG do eighter everything or just the above calculation in double) Or do you have another idea why this problem appears? Greetings Hagen ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=10496#10496 _______________________________________________ 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
