(In reply to Marek Olšák from comment #4)
> I think the hw doesn't have a clipper, though it shouldn't be hard to verify
> if it's true. Yeah, draw could use some optimizations for the clipper, e.g.
> the guardband, but simply doing culling (not clipping) should be enough for
> point sprites.

That's what I meant with guardband clipping: there's no actual clipping, but
the hw will still cull pixels outside the viewport. Hence it probably would be
better if draw wouldn't clip if a primitive doesn't fit into the viewport, but
fits into the (hw) guardband. (And you are right that point sprites are a bit
of a special case.)