Re: [Algorithms] Current state of shadow maps?

[Megan F. <sha...@gm...>]

Well, let's take the army with torches but apply stencil shadows
instead (and let's say they're on a field of battle, a heightmap) -
how is that still not a nightmare scenario?

With shadow buffers (using Tom's method), you'd end up:

- Creating a lot of frustrums, but not necessarily 1 per reciever per
light - it's very likely you could merge quite a few of those
frustrums together, given an army is usually walking in close
formation

With stencil, you'd end up:

- Casting your extrusions back for every light/occluder pair.  You
can't really merge (I don't think?), so that's "it."


Especially after using Tom's handy-dandy frustum merge-o-matic method,
it seems like the two methods would be comperable - mind, both would
probably keel over and die in a slurry of render passes (and in both
cases, you'd probably enable your "oh god we're in trouble start
merging nearby lights into single lights" optimization code), but it
seems like neither does terribly well.


I'd thought the "big" win scenario for stencil over buffers was more
scenes with few occluders and many recievers (that is, your average
FPS environment)?

> Stencil volumes win the indoor/urban, night scenarios (think doom3, or ne=
verwinter nights for the record)
> - shadows from vegetation can be neglected.
> - many omnidirectional light sources, or lightsources with large frustra,=
 for which shadowbuffer is unoptimal (too many render targets)
> - most light sources have small screen space extent and world extent, so =
stencil is not expensive
>=20
>=20
> However shadowbuffers have other qualities that make them attractive (ima=
ge based, soft edges), so it would be desireable to use them for all purpos=
es. It's just a pity that they are so unfeasible for omni lights (I imagine=
 an army with torches here ...).