If OSG_OPENGL_PROFILE="GLES3" => GraphicsWindowIOS will create gles3 context. If failed, GraphicsWindowIOS will create gles2 context. Multisampling also working. " git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14831 16af8721-9629-0410-8352-f15c8da7e697