Wednesday, November 19, 2008

MIGS (Post 3 of N): Jason Mitchell's talk

Jason Mitchell (former ATI, now at Valve a couple years) gave a talk on "Connecting Visuals to Gameplay)


Rough notes below. Lots of screens and some video from Team Fortress 2 and the recently released "left for dead". Worth googling both before you read the notes below.

We'll look at two games today
TF2
- Distinctive silhouettes
- Stylized rendering
Left for dead
- Dark, gritty horror
- “filmic effects"
- Lessons from TF2

TF - Orignally as a quake mod 10 years ago, then half life mod
Class is selected by players. 
Initial TF2 1999 screenshot.
- Screen showing more “realistic” FPS, nothing distinctive
- Evolved to be stylized
Why?
- Gameplay (different classes)
- Readability
- Branding

Read hierarchy: What does player attempt to ascertain?
- Friend or foe (color)
- Class – run or attack (distinctive silhouettes, Body proportions,  Weapons, shadows, hats and clothing folds)
- Selected weapon – what’s he packin?
- Highest contrast at chest level
- Greadient from dark feet to light chest
- Lots to draw your eye up to chest level.

Early 20th centry conmmercial illustration influences.
Cornell, Leyendecker, Norman Rockwell
JC Leyendecker was biggest influence
- Clothing folds
- Rim highlights (light source orthogonally) – helps silouetttes pop.
- “red terminator” – where normal crosses orthogonal – increases saturation at that point, makes it red – actually makes sense inf you think about subsurface scattering

Screenshot from early short videos (“meet the heavy”)
- Before and after 2D paintover to make the image pop – rim highlighting was awesome.

Character creation
- Character silhouette (showed silouette of elephant, everyone gets it, despite it being orange)
- Bulding block, Identifiable at first read
- Interior shapes, Keep it iconic
- Work out design in ¾ pose
- Model sheet
- 3D model
- Front rear views
- Base ambient occlusion map, that's then used as a guide for painting skin
- Final character
- Iterate on the above

Environment design
- Create a compelling immersive worlds
- Team districntion through material hue/saturation/etc desaturate relative to players.
- Uncluttered painterly look.
- Bases – blue featured concrete, steel; red featured wood, sand.
Miyazaki was an influence – brushwidth foreshortened example. 
--
Left for Dead

Co-op first person horror, Dynamic shared narrative – "experience an action movie with friends"
AI director

Photo  - The valve “Shipping machine” (When games go live, they have a BIG RED BUTTON on a control panel of sci-fi proportions that Gabe hits at midnight. This then sends an 'enter' keystroke to a person's PC. Awesome. Took a pic, will post soon).

Gameplay movie (awesome).

Lessons learned from TF2
Filmic effects
Shaders enhance dark setting.

Filmic
-Color correction
-Grain
-Vignette
-Local contrast enahancement
-Dynamically communicate game state

Showed step by step
Color correction made it a bit greyer, desaturated
Grain – detail in greyed out darker areas
Vignette – mainly along top, to focus attention down at center.
Local contrast – highlights area around the player

We’re not film, we’re an interactive medium, so we might have info and cues we are looing to give to player
“sideband communications channel” like music score to film director
Gave example of normal stress level vs high stress
(local contrast driven higher, more stark
"Third strike", totally washed out, stark contrast - almost black and white.

[one note is that all the filmic effects were weilded subtly, but in sum were dramatic. good lesson here]

Lighting for darkness
Support fiction
- Fires
- Headlights of abandoned vehicles “clearly something has gone wrong”
- aid naviation - players tend to follow light.
"Smoking the set"
- Separate foreground from background
- - fog, light colord fog in dark areas to contrast with silhouettes, of infected in mid-ground
- Particles – adds atmostphere and helps accentuate silhouettes.
- Subway example of grey fog.
- Particles coming up from manhole
Reload shove and muzzle flash
- Player is the light source
- - increase drama and immersion (when Flashlight is attached to the weapon, and you are using it to light up a dark hall, reloading has consequence).

Self shadowened normal mapping
- Normal mapping locally alters surface orientation, causing detailed lighting effects
- HL2 “radiosity normal mapping”
- Turned out to be free by refactoring shader code
[note effect here was noticable but not huge, felt like he delved a little to deep into this one vs others. Hmm...]

Wet environments
- Film technique
o Wash down the set to geth that moview dark look
o Film noir
- Adds details to dark settings while still feeling dark

Then showed gameplay elements to show the above.

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