00:01In this paper, we present a set of artistic choices and real-time shading techniques
00:05which support each other to enable the unique rendering style of Team Fortress 2.
00:10Heavily influenced by early 20th century commercial illustrations,
00:13the 3D models and shading algorithms in Team Fortress 2
00:16work together to quickly convey geometric information using rim highlights
00:20as well as variation in luminance and hue
00:22so that players are able to quickly identify other players in the game
00:26and assess the possible threat.
00:30Through very intentional art direction, this goal was supported by designing characters
00:35with distinct silhouettes that can be easily identified even with no lighting cues.
00:39The body proportions, weapons, and silhouette lines were explicitly designed
00:43to give each character a unique silhouette.
00:45In the shaded interior areas of the characters, the clothing folds were designed to echo silhouette shapes
00:51in order to emphasize the silhouettes as observed in the commercial illustrations
00:55which inspired our designs.
00:58For the architectural elements of the world associated with each of the two teams,
01:02we define specific contrasting properties.
01:05While the red team's architecture tends to use worm colors, wooden materials, and angular geometry,
01:10the blue team's buildings are composed of cool colors, industrial materials, and orthogonal forms.
01:16By maintaining a minimal level of visual noise in our world design,
01:19we employ an almost impressionistic approach to modeling.
01:22This philosophy was also central to our texture painting style throughout the game.
01:28The red and blue colors used to paint opposing areas of the game world
01:31aren't analogous to one another, as guided by this reference color swatch.
01:35With muted colors dominating, and small areas of saturation used to provide further visual interest.
01:41The texture maps used on the 3D world are impressionistic and maintain a minimum level of visual noise.
01:46This is consistent with background plates found in animated films,
01:49particularly those of Hayao Miyazaki, in which broad brush strokes appear in perspective,
01:54as if present in the 3D world rather than on the 2D image plane.
01:58We apply this same approach because we feel that its inherent frame-to-frame coherence
02:02has superior perceptual properties to an image-space painterly approach.
02:07To shade our characters, we combine a variety of traditional and novel lighting terms.
02:11Here, we see a character with a traditional clamped Lambertian diffuse term and constant ambient.
02:16You can see that the character loses definition for pixels not hit directly by the light source.
02:21We scale, bias, and warp the Lambertian term to achieve a look consistent with our illustrative influences.
02:26Instead of a constant ambient term, we sample from an irradiance volume
02:30in order to provide a higher quality, spatially varying directional ambient term.
02:34Here, we show this term added to the warped per-light diffuse contributions.
02:38And here, we show these diffuse terms multiplied with the albedo.
02:41We also add a number of view-dependent terms to further enhance the look of the characters.
02:46Traditional phong highlights from up to four local lights are incorporated,
02:49where quantities such as a scalar mask, fresnel parameters, and specular exponents can be specified by artists.
02:55We combine these phong highlights with additional broad phong lobes,
02:59which are modulated with a harsh fresnel fall-off, causing them to appear only at grazing angles.
03:04Finally, we add in a dedicated rim term, which is derived from our irradiance volume,
03:09so that characters are always highlighted with an appropriate rim term,
03:12even if they are far away from local light sources.
03:15This combination of art direction and technology choices
03:18has enabled us to create a compelling visual style
03:21while serving critical gameplay goals,
03:23such as the ability of players to readily identify each other
03:26during the fast-paced action of Team Fortress 2.
03:33Thank you.
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