Hi Glenn Waldron, Thanks! I solved my probelm and I understand why it'not always commutative.
I think the right order of the multiplication is gl_ProjectionMatrix * gl_ModelViewMatrix * gl_Vertex. I tried in shaders both orders of the multiplication, it turns out that gl_Position = gl_ProjectionMatrix * gl_ModelViewMatrix * gl_Vertex gives the correct scene while the other order gives the wrong scene. Thank you for the answer :) Cheers, Ying [quote="gwaldron"]Ying,Matrix multiplication is not always commutative: http://math.stackexchange.com/questions/170241/when-is-matrix-multiplication-commutative (http://math.stackexchange.com/questions/170241/when-is-matrix-multiplication-commutative) If the values are out of range, it may be because your point lies outside the projection matrix near and far range. You can call double fovy, ar, znear, zfar; projectionMat.getPerspective(fovy, ar, znear, zfar); to check the values. Glenn Waldron / @glennwaldron ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60456#60456 _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
