Team Fortress 2 Character Lighting

[Andrew Scherkus]

Just thought some of you might find this presentation from the Game
Developers Conference really interesting. In summary, the makers of Team
Fortress 2 describe the art style of the game and how they developed shading
and lighting models to replicate the style of early 20th century commercial
illustrator J.C. Leyendecker.

Of particular interest are slides 27-58 where they break down every piece
of both the view-independent and view-depenedent character lighting
equations. You might be surprised at how many of the lighting equations
used in A4 show up...

http://www.valvesoftware.com/publications/2008/GDC2008_StylizationWithAPurpose_TF2.pdf

Andrew

[Jeff Dicker]

I'm immediately struck with a couple of comments about this with respect
to the projects:

1) Note how much better the Heavy model looks because of phong shading.
There were a couple of final ray traced scenes that could have
benefited greatly from phong shading (though it was not required!).
Thanks to phong shading, the model appears to be smooth despite not
having a particularly large number of polygons (you can see the
tesolation). Implementing this in a shader (usually known as per-pixel
shading, since more values than normals may be interpolated) is trivial,
and it's also not hard to implement in a ray tracer.

2) If you are working on an OpenGL project and planning on implementing
shaders, TF2 style shading is quite possible. As Andrew pointed out,
n.l and r.v are the basic keys to diffuse and specular shading - making
the tweaks Valve did, like a half-lambertian lighting term, should be as
easy as passing a couple more variables to the shader. Some parts are
trickier, like the 2D toon-shading lookup, but if you're looking to get
some subjective marks those slides could be helpful!

-Jeff

[Craig S. Kaplan]

I don't know what exactly is in that talk, but I saw a related talk
last year at a conference. There's an accompanying paper for anybody
who'd like to delve a little deeper (or have access to more concrete
formulas for lighting):

http://portal.acm.org/citation.cfm?id=1274871.1274883

(If you're on campus, you should be able to open the PDF on that page
directly; if you're off campus, you'll need to go to the library's web
page and click "connect from home", then try the URL with
".proxy.lib.uwaterloo.ca" after "acm.org" above.

--
Craig S. Kaplan If civilization is to survive,
University of Waterloo it must live on the interest,
Cheriton School of Computer Science not the capital, of nature.
http://www.cgl.uwaterloo.ca/~csk/ -- Ronald Wright

[ad...@glados.cc]

Very interesting - however recent updates have significantly ruined TF2's artistic style. There's an insightful article on http://www.tf2intel.com/