Thanks Paul, I understand how to go through the OpenGL pipe to convert from World to Screen coordinates and back
eye_coordinate = world_coordinate * view_matrix; clipspace_coordinate = eye_coordinate * projection_matrix; screen_coordindates = clipspace_coordinate * viewport_matrix; But I'm unclear how to do it to get distance subtended by a single pixel. Can you point me to an example or an article? Best Regards -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Paul Martz Sent: Tuesday, December 01, 2009 6:26 PM To: OpenSceneGraph Users Subject: Re: [osg-users] Distance Per Pixel Calculation Hi Nelson -- Given a world/eye coordinate distance from the eye, a viewport, and a projection matrix, you can determine the world/eye coordinate distance subtended by a single pixel by back-transforming through the OpenGL transformation pipe. At a former employer, I used such a technique to control the LOD of our rendered terrain. Paul Martz Skew Matrix Software LLC _http://www.skew-matrix.com_ <http://www.skew-matrix.com/> +1 303 859 9466 Cysneros, Nelson A CIV SPAWARSYSCEN-PACIFIC, 56510 wrote: > I'm trying to determine the given distance per pixel (or group of > pixels) on my scene. > > I'm using an Intersection to get the World XYZ coordinates at a given > Screen XY point, then getting a second set of World XYZ coordinates > after incrementing the Screen point. > > Then Calculating the distance between the two World XYZ coordinates. > > Is there a better way of doing this? > > Thanks > > > > ---------------------------------------------------------------------- > -- > > _______________________________________________ > 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.or g _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
