About Writing OBJ file

[Fantasticos]

https://github.com/openscenegraph/OpenSceneGraph/blob/683403244a489fe3e71f1533580c22e099774a36/src/osgPlugins/obj/OBJWriterNodeVisitor.cpp#L300

Should this line be updating "++iptr" to iterate lines one by one? It seems to be connecting dashed lines, like 1-2, 3-4, 5-6, instead of 1-2-3-4-5-6.