When Uru is open source, it needs to have a system that puts all light source sprites onto a layer right in front of the camera, and turns them on or off depending on whether or not an object is obscuring the light source. You know, the way civilised games render light sources.
I think Eder Tsogal has such a programme at work for the sun already, albeit a crude version that has glare/no glare, rather than varying intensities.
(This is coming from the guy who has no experience of programming such things yet; pick apart at will.)
If I had a signature, this is where it would be...