RE: [Algorithms] plants that shadow other plants

[Chris B. \(BUNGIE\) <cbu...@mi...>]

> -----Original Message-----
> From: gda...@li...
[mailto:gdalgorithms-
> lis...@li...] On Behalf Of De Boer
> Sent: Tuesday, July 22, 2003 12:27 PM
> To: gda...@li...
> Subject: [Algorithms] plants that shadow other plants
>=20
> What techniques are used for plants that shadow other plants?
>=20
> Say you have a big tree and lots of small plants underneath the tree.
So
> many plants you can't even see the ground. What would the best way of
> doing
> shadows on the plants? Projecting the shadow onto the ground is almost
> useless since you can't see the ground. Baking lighting in lightmaps
for
> the
> plants is one way - is this how everyone does it? I was hoping for
another
> simpler solution.
> Perhaps project on to the ground, have a boundary, if plants are
inside
> that
> draw them darker. Maybe using a stencil.
>=20
  Stencil volumes aren't workable for high-frequency shadows like that
of canopy foliage. If you are worried about complex self-shadowing
behavior for the ground foliage, you would have to use a shadow buffer,
and it could be tough getting good resolution.

  The only solutions I've seen proposed have either used low-frequency
lighting only (lightmap color used to tint the entire plant), or have
involved splitting your foliage into layers (canopy, bushes, grass) and
using texture-based shadowing.

  Nobody has really done this well that I know of. Except maybe the GSC
Gameworld guys with Stalker, but since they haven't shipped we haven't
had a chance to pick apart their algorithm yet. I know some of them read
this list, perhaps they will answer your question. :)

--
Chris Butcher
Networking & Simulation Lead
Halo 2 | Bungie Studios
bu...@bu...