The Softbox texture is really useful and versatile for product rendering. And I suspect that from a programing standpoint this map is really simple. It would be nice if it was available in Corona too.
Actually don't port/copy it and make a "CoronaSoftbox", just make in cross compatible (from I user standpoint, we don't care what you have to do behind the curtains) and call ChaosSoftbox and have it supported across all renderers.