July 31, 2008 8:00 AM | Simon Carless
[Another of the complex lectures from last week's GameFest in Seattle that's well worth recapping on GSW - thanks to Christian Nutt (notes) and Michael Zenke (write-up) for encapsulating some really interesting concepts on just how art direction and gameplay imperatives blend.]
Microsoft's recent Gamefest featured a number of discussions talking about both gameplay and art, but none entwined the two disciplines as closely as a talk from two Valve employees.
Team Fortress 2 art director Moby Francke and Randy Lundeen of the Left 4 Dead team offered attendees a peak behind the scenes at Valve's unique design philosophy.
Team Fortress 2
Moby Francke kicked things off with an extensive discussion of Team Fortress 2, prefacing the new with an examination of the old. Francke explained that Valve hired the team behind the original TeamFortress Quake mod.
When development of the sequel to the eventual Half-Life mod version commenced, it was being created with a realistic military style, both in visual and gameplay terms.
Of course, it didn't end up launching as that realistic game. Instead, "TF is over-the-top from a gameplay perspective - you can rocket jump, you can magically heal people. They started to run into problems during play testing."
For example, there was a tiny medic patch on the sleeve of the medic, but it was nearly impossible to tell medics apart from other players.
After the fact, the Valve designers came to the conclusion that they should aim to match the game's look to the gameplay. This ties very closely into previous comments the artist has made about the current state of game art direction.
"Due to this high-paced, very stylized gameplay, we thought of going for something more unique, something that's more shape driven, color-driven," Francke noted.
He continued, "Readability was a very important thing - we wanted the characters to stand out in the world, and the ability to tell who is who. From a branding perspective, TF2 differentiates itself from other games quite easily."
Making the characters stand out required the artists and designers to develop multiple ways for players to "read" the world. They ended up with three different levels of readability.
The first was through simple colors: "Starting off with teams, we wanted to differentiate the characters through the colors alone inside the world. This is really the best way we could describe it." They used a color swatch that has a general set of colors per teams, not a simple red and blue distinction for clothes.
The second part of readability was grossly distinct physical shape. Color differentiates teams, but what class is your opponent? "We did it through silhouettes," said Francke. "We wanted very unique shapes; you can tell they have very different shoes and hats and clothing folds."
Francke concluded with the third level of readability, fine details for players to remember: "We wanted to put all the detailing up towards the chest area of characters, so you could easily see the weaponry - the patches, vests, bandoliers, neckties, caps, pants. They all contribute to this readability factor. We then also gradated the character from the dark bottoms to the contrasting upper torso for better readability."
The artists looked to three specific illustrators for the game's general look, each from the early 20th century, including Dean Cornwell and Norman Rockwell.
The third, and possibly the most important, was JC Leyendecker. From Leyendecker, artists pulled a sense of color, folds, shapes, and edge lighting.
Noted Francke, "A lot of his lighting was rendered from warm to cool - cool in the shadows, but never going black. He really rendered his silhouettes with function, like clothing folds. This will be read in the silhouette and the interior shapes of the characters when hit by the light."
The artist continued, "He used rim highlighting to pop the character from the world but at the same time to give the character more information. We used the same idea. We didn't want to go the cel-shaded route, we wanted to go more true to the way that lighting occurs."
To demonstrate, Francke showed a hand-painted rim lighting test on a screenshot which pops out the character: "At the same time you can see that without it, it just seems a little bit boring. You can see that the shadowed side gets lost into the background [without it]."
He offers up some comparisons of silhouettes, another Leyendecker signature: "It's a building block of character design - it's identifiable at first read. We work out the character in a three-quarter pose. The reason we do that is so you can get a little more information into the character, and it can be used as information for going into the modeling aspect."
This thought process even extended to black and gray models: "We solve the interior shadow shapes off of the interior design. There are some discrepancies but overall the character still obeys the model sheet."
This "readability" extends even to the world around the characters, he noted: "To contrast the two teams, for the red team we used predominantly warm colors - some grays, but they're warm as well. We used natural materials such as woods and red brick, and angled geometry."
"Then for the blue team we used cooler colors, and industrial materials such as concrete and steel, and orthogonal forms. Our world is hand-painted, lovingly," Francke continued. "We're actually analyzing the photo reference and then translating. Sometimes we look at other art for inspiration, like Miyazaki and some Disney as well."
He noted, particularly, that the brick and wood work even as hand-painted artistry: "It doesn't have to be a photo to show what the material is in some cases."
Left 4 Dead
Randy Lundeen, of the Left 4 Dead team, opened by his portion of the talk with some broad context. Left 4 Dead is an as-yet-unreleased Source engine title from Valve - originally developed by Turtle Rock studios, now known as Valve South. It's a cooperative zombie horror game that pits a group of players against an almost-unstoppable horde of onrushing undead.
Art is important to the game, but there are a lot of unique technological decisions going on as well. The game's "dynamic narrative" is entirely down to what the team calls the "AI Director." Explained Lundeen, "It's a presence in the game that is keeping track of all of your health, your ammo, and how you're playing, and it's controlling the pacing of the experience you're having in the game."
Showing imagery from the still in-development title, he continued: "As you can see, it's a very different game from TF2. It's dark and gritty, a cinematic experience. At the same time we want to take all of the lessons [learned by the TF2 team], particularly [regarding] the silhouettes."
The result is a game that relies on a number of filmic tricks to get across elements of tone and mood. These effects include color correction, artificial grain, and vignettes. Of course, the AI Director affords game-specific effects one could never see in a movie, such as local contrast enhancement, and a dynamically-communicated game state.
To begin with, Lundeen showed the audience an effects-free screenshot of the game. Minor visual changes are the first things added to this simplistic image. "First, we color correct," he said. "It simplifies the palette, but we still wanted health packs, blood, exit points to pop. We did that with a saturation threshold. Anything below that moves towards gray."
From there, the team added grain to the imagery: "We had a lot of dark spaces and a grain does a good job of implying detail in darkness. What we found from playtesting we found that if we apply grain uniformly, people would get tired. In the darker places, like a shadow, there's more grain, but in the brighter areas there's no grain."
"Another film effect is vignetting," he went on. "This is a lens artifact where you get dark edges around the edge of the screen. We decided we wanted to do vignetting just in the top corners. This is a really great looking effect."
Even still, he noted, there is such a thing as too much processing of the image. He elaborated on that point: "We didn't want to do it all around because we didn't want you to feel like you're looking through binoculars or a scope. Once we got it in the game, people didn't feel like it was obtrusive and it did a really good job of softening the top edge, focusing the gameplay down towards the center of the screen where you want your players to look."
With these elements in place to set the tone of the overall experience, the team explored options to enhance gameplay through visuals. They accomplished this by having visual cues related information to the player.
They accomplish this in a few ways, said the Valve staffer: "One is the notion of third strike. If a player goes down or gets killed in this state it's bad news." The third strike appears to the player as if the entire world were a black and white negative, with high contrast at the edges. "If the player is in this state, the player knows they need to get health right away."
The AI Director's omniscient knowledge of the game state allows the game's visual tone to change even before events take place. Said Lundeen, "We take the local contrast and crank it up. Everything gets sharper, like there's an adrenaline rush, and things start to feel more clear, like people get in near-death experiences. What the Director is subtly saying to you is, 'I am going to spawn 100 zombies around the corner.'"
Lighting is also used to dramatic effect in the horror title, as might be expected. In some cases, the drama and gameplay can be enhanced just by having a source of light. Offered Lundeen, "There's a warm point down the end of the street where maybe the player feels like it's a safe place to go." This lets the designers plan the action around players staying in the light.
"For navigation, it gives us the opportunity to use these very liberally. In our playtests, especially in a very dark game we've discovered that players will go wherever there's lights, so we just set these up and our players will go like a moth to a bug zapper," Lundeen chortled.
The game's narrative is affected by this simple lighting as well, he noted: "Another source of lights we decided to use are car headlights. They tell a good story, a sense of abandonment. When you see a car with its headlights on and nobody around, you know something's wrong."
"Another common film technique that we looked at it to help enhance silhouettes is smoking the set. You use this to separate background and foreground elements," Lundeen continued.
The problem there, he admitted, is that gameplay and visual design can sometimes interact with each other negatively: "If we just went with a more accurate, darker fog, we found it's really hard to get that silhouette read that's so important to the players. Without the silhouette read players would be too surprised. When we'd get feedback people would be really frustrated."
By lightening the fog, "people can see things much better and it's much more dramatic," he explained. "When you can see the zombies climbing over the rubble you have a much better chance to coordinate with your team. The players have a much better time and can anticipate the attacks."
Player-controlled light sources are just as important to take into consideration, according to Lundeen. "The flashlight, for a dark game, is a very important tool. What we found by just moving [the flashlight] onto the weapon is that it's a little off center and it's much more dramatic and you get more interesting shadows. When you reload your gun, the flashlight disappears now. When you shove an infected, it goes out of the way, and also the muzzle flash is creating all these great shadows as well."
The visual design here even helped to enhance the team's intended multiplayer design: "By putting the light source on the gun it helped encourage that co-op with teammates," Lundeen said. It also required some technical considerations as well: "Normal maps were an important thing to have on as many surface as possible," because it's a dark game generally lit with flashlights.
Self-shadowing normal maps added greater surface richness at no code cost, he pointed out. They also decided to make the environments as lush as possible, as a nod to dark films.
"Another film technique that we noticed is that whenever you watch a dark setting mysteriously it's always wet. It creates highlights, it creates parallax, it creates moodiness. It makes it feel more miserable, so that was perfect for our product," he concluded.
Responding to an audience inquiry, Lundeen addressed the team's decision to change the game's character models, a move that has garnered some criticism from fans.
"What we found in a lot of our playtesting was that for the original main characters, players would have a really hard time separating them from the zombie hordes," the artist explained. "It was pretty tricky to pick out who was who - people were just going in spraying bullets everywhere."
"What we wanted to do specifically was take those lessons we learned from TF2. The survivors now have different silhouette reads, different colors. There's a dynamic light on the flashlight that's kicking back a little bit of light to illuminate their faces. The character redesign was to alleviate issues we saw while playtesting," he concluded.