Hi, As far as I know it's not explicitly specified but is implicit in the projection transforms. Assuming the ModelView matrix is the identity, the matrices generated by the traditional Ortho/Frustum functions would result in a vertex's Y value determing its height on the screen. That scenario is enough for me to adopt Y as the "natural" up axis. Also, according to the OpenGL Red Book there is a default coordinate-system orientation:
> The frustum has a default orientation in three-dimensional space. You can > perform rotations or translations on the projection matrix to alter this > orientation, but this is tricky and nearly always avoidable. Cheers, Mik[/url] ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=42806#42806 _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
