I was looking at implementing lighting on an indexed cube, and was trying to figure out what to do re: the normals. I already knew you can only use 1 index per draw call, so you can't just have every vertex and every normal defined once, and then I read this Q&A for more info...
http://stackoverflow.com/questions/2954349/when-should-i-use-indexed-arrays-of-opengl-vertices
Does that mean then that for any case where you want every face to have its own shading, you can't really use indices at all and have to define every separate instance of a vertex-normal pair? So if you wanted to have old-fashioned flat shading (e.g. Frontier Elite II) you couldn't get any benefit from using indices?
When I think about it, and how you have to use the same indices for the normals as the vertices, it seems like you'd have to specify as much data as if you just didn't use indices in the first place.
Or is there some way of using them for a more minor gain?
I suppose that either way, it's probably not a huge issue since any model using flat shading isn't likely to have a lot of vertices (it's meant to look polygonal after all) so the performance gain from indices would be less important anyway... or so I imagine.