HI Nick, The svn/trunk and recent dev releases of the OSG have a CameraManipulator::updateCamera(osg::Camera&) method that allows you to set any properties you want on the View's Camera rather than pulling the view matrix as was done previously.
The other bit of the jigsaw for you specific implementation requirements might simply to not use a CameraManipulator at all and just set the view and projection matrices on each new frame within your own frame loop. CameraManipulators are only one way to control the view and while often convinient to use in their default form aren't all required usage. Robert. On 17 July 2013 02:56, Nick McEvoy <[email protected]> wrote: > I'm writing a camera manipulator but have an issue where I need the > manipulator to be visited during the update traversal (& after the scene > graph has been updated). Without going into too much detail ... the basic > reason I require this is ... that my manipulator needs to set the > orthographic projection matrix extents based on the updated scene. I really > need to set the orthographic projection matrix extents at about the point > where the camera view matrix is applied (see point 2c below). > > So as we all know the viewer performs: > 1. event traversal > 2. update traversal > 3. rendering traversals > > And my area of concern is the viewers update traversal (point 2) which > does the following: > 2a. visits the scene graph > 2b. visits the camera > 2c. sets the cameras view matrix (using the camera manipulators inverse > matrix) > > BUT it does NOT visit the active manipulator or have any way for the > active manipulator to apply a projection matrix if it so wishes > (specifically at point 2c). :( > > I've considered and tested the following, but they all feel like hacks: > - set the orthographic projection matrix extents in > MyCameraManipulator::getInverseMatrix(), called at point 2c. But I think > this is a bad idea because this method is really used for other purposes. > - have my active camera manipulator add an update callback onto the > current camera and so therefore set my projection matrix extents when I'm > visited at point 2b. But then I must also have code to remove the update > callback from the camera when my manipulator is no longer active or > removed. My implementation on this works, but it feels dirty. > > Does anyone have a simpler/cleaner solution? > > The real question is why is there no mechanism in OSG to allow the camera > manipulator to update the projection matrix at the appropriate time? Maybe > something like the ideas below (++1) or (++2) could be considered? > > > Code: > > void Viewer::updateTraversal() > { > if (_camera.valid() && _camera->getUpdateCallback()) > _camera->accept(*_updateVisitor); > (++1) if (_cameraManipulator.valid() && > _cameraManipulator->getUpdateCallback()) > _cameraManipulator->accept(*_updateVisitor); > > if (_cameraManipulator.valid()) > { > _camera->setViewMatrix(_cameraManipulator->getInverseMatrix()); > (++2) _cameraManipulator->updateProjectionMatrix(); > } > } > > > > > Thoughts? > > Cheers, > Nick[/code] > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=55232#55232 > > > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >
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