[osg-users] PositionAndAttitudeTrabsform
Hi, beginner question : i just used the PositionAndAttitudeTransform with setScale(0.1, 0.1, 0.1) to scale down an object in my scene graph. the object indeed scaled down but the light behaviour changed totaly from blue to white, like in specular highlights. for a different object it just colored everything differently. to my understanding scaling an object should not change normals or colors, and therefore the coloring should stay the same and not change that drastically. what am i missing ? Thank you! Cheers, amit -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=22021#22021 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] PositionAndAttitudeTrabsform
2010/1/1 Gordon Tomlinson gor...@gordon-tomlinson.com Your right it does not scale the normals. So the normal are no longer correct for the model once you scale it See http://www.vis-sim.com/osg/osg_faq_1.htm#f19 That should really mention that rescale only works with uniform scaling. -- http://www.ssTk.co.uk ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] PositionAndAttitudeTrabsform
PositionAttitudeTransform, like any OSG Transform, sets the OpenGL ModelView matrix, and that matrix is used to transform the normals (see the OpenGL spec, or any OpenGL book). So, scaling an object does indeed scale the normals. GL_RESCALE_NORMAL works only for uniform scaling, as noted in Simon's post. For non-uniform scaling, use GL_NORMALIZE. If you're using shaders (and I don't think you are, but if you do in the future), a third option would be to transform your normals directly in the shader code, giving you total control over how they are transformed. Paul Martz Skew Matrix Software LLC _http://www.skew-matrix.com_ http://www.skew-matrix.com/ +1 303 859 9466 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] PositionAndAttitudeTrabsform
Hi, Right on the button, Thank you very much amit -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=22030#22030 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
