Consider a game set on a planet, where you can freely roam around, implemented with some suitable subdivision with LOD scheme. Intention is to use shadow volumes for all lighting to have good looking shadows for moving light sources and to avoid having multiple lighting schemes. Ideally even the planet would be shaded with shadow volumes, which brings up the need to have soft shadows, as otherwise shadows on and near the terminator would be unacceptably crisp and would wobble terribly over huge tracts of land as the LOD of the mountains casting shadows would change. So the question is, what would be a good way to implement these soft shadows. They are only needed for the sun, but since the player could travel to the terminator, any object must be able to cast a soft shadow from the sun. Any method other than shadow volumes would also do, as long as it correctly shades objects in shadow of the terrain, without nasty artifacts. For smallish shadowing objects the shadow could probably be attenuated based on distance from the object to get the effect, but this wouldn't really work for the terrain. [Edit] Actually, I just realized that the attenuated shadow trick might actually work for the mountains anyway, because the gradual change form light to dark at the terminator is caused by the atmosphere, i.e. ambient lighting. For example, the moon's terminator is much sharper. Still, the problem might crop up, so any ideas are appreciated. [Edited by - SnotBob on May 8, 2008 5:26:26 AM]

Yes, I've been reading on some general soft shadow volume techniques and they certainly aren't cheap. I was wondering if there might be some kind of a trick that would specifically fit my problem.

I fear that shadow maps might have much too low resolution, considering the magnitudes involved. Although maybe using some kind of LOD scheme with them might do the trick.

Quote:Original post by Yann L
There are lots of tricks to reduce the fillrate consumption of shadow volumes, but the most efficient one is to not use them at all.

I sense that you prefer maps over volumes. I have been under the impression that shadow maps frequently display undesirable artifacts, but if that is no longer the case, I shall consider using those solely (once I get the spare time to actually start working on this, that is).