HI Dirk - >> What confuses me is that renderAction->push_matrix() takes a matrix >> argument, whereas gl's does not. >> > > RenderAction::push_matrix(Matrix m) > > is equivalent to > > glPushMatrix() > glMultMatrix(m) > > The pops are the same. There is no equivalent of glLoadIdentity right > now. What do you need it for? > > I think I came up with a solution, but here's what I'm doing anyways.
I need to hang a target off of my camera. The "target" is really a transform similar to a billboard which rotates to face the camera. I need the target to always be a fixed offset from the camera position (that is, its position in world coords, relative to world coords, not relative to the camera orientation). I already use billboards attached to transforms to place objects on the screen at a fixed position, regardless of camera orientation. In the present case the target needs to reside at a fixed distance from the camera, but the user must steer towards the target, which the evil and tricky experimenter moves about. My original intent was to simply make a simple transform and push it onto the stack -- after clearing the stack with something like glPushMatrix() glLoadIdentity() glMultMatrix(myTrans) but I ran into trouble with RenderAction and my misunderstanding (clarified with your replies - thanks). I had already made this work -- but only when I attached my node to the scene root - I hadn't been able to apply it to any sub-nodes. Over the weekend I took some time to understand how the billboards work and was able to lift a portion of the billboard code (where the axis of rotation == null and alignToScreen==true) and, with a slight modification to one of the translations, make it apply to my situation. Now I've got a more generally useful NodeCore, and (I think) a better handle on yet another aspect of OpenSG. Thanks again for all your help! Dan -- Daniel J. Sperka UC Davis Center for Neuroscience ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Opensg-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/opensg-users
