Re: [Algorithms] Foliage rendering in GPU Gems 3

[Jeff R. <je...@gm...>]

The crysis vegetation article was pretty simple, basically they do a
standard phong lighting model with an added transmission term (basically
just -N dot L times an 'opacity mask'). Specularity is important. All the
leaves are alpha tested. They use artist painted vertex colors as weights
for various physics parameters, like stiffness. And that was about it, iirc.

The next gen speedtree rendering article has a lot more in it, the coolest
IMO is the shadow map offset trick. Each leaf card has a grayscale map that
represents a depth offset for the purposes of determining shadow map
coordinates - this keeps the shadow map from stretching unrealistically
across the flat face of the leaf card. The article also has a description of
a geometry shader to put textured fins on the silhouette of the trunk to
give it a bumpy outline. There is also mention of the use of
'alpha-to-coverage' (google that term :-P), and specularity and diffuse
transmission similar to what the crysis folks are doing.

Hope that helps; but the book is real cool and full of interesting stuff.
I'd advise you to just get copy :-)

Jeff R

On 10/2/07, Juhana Sadeharju <ko...@ni...> wrote:
>
>
> Hello. GPU Gems 3 has papers on foliage rendering.
> Could anyone write a short summary of the techniques?
> Anything which helps in implementing them without
> buying the book. (Cannot afford, and anything
> I succeed to write comes out as open source free(dom)
> software.)
>
> ch4: Next-generation SpeedTree rendering
> ch16: Vegetation procedural animation and shading in Crysis
>
> After the last time I wrote about open source tree generation
> and rendering situation, one more software has been released:
>   http://ngplant.sourceforge.net
>
> Thanks,
> Juhana
> --
>   http://music.columbia.edu/mailman/listinfo/linux-graphics-dev
>   for developers of open source graphics software
>
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