CGSociety :: Game Production Focus
21 January 2010, by Peter Rizkalla
The first Left 4 Dead exhibited gorgeous facial animations and stunning character designs. This time around Valve has pushed Left 4 Dead even further. I talked with a few of the devs at Valve to learn
more about the design direction they wanted to push with Left 4 Dead 2.
We have Jeremy Bennett on characters, Randy Lundeen on environments and our Valve PR guy Doug Lombardi on congas.
In any game, movie or animation that exudes good design, it is likely that questions like "What kind of ideas didn't make it to the final version?"
will arise. The main idea behind Left 4 Dead 2 was to implement those good design ideas that didn't make it into the first game and expand upon them with even newer ideas.
"We had a lot of ideas while working
on the original Left 4 Dead that didn't make it into the game for one reason or another and the team was excited to continue the franchise by putting these ideas
into a sequel," said Bennett.
"As with any sequel, we wanted Left 4 Dead 2 to expand the universe
of the franchise, create a fresh world design, introduce new characters and creatures, explore new game play scenarios and introduce new tech features."
Visually, Left 4 Dead 2 had to differentiate itself from the first title. Largely, this would mean that the locale and environments had to be
fresh. "Gone are the back alleys of Philadelphia and the Pennsylvania countryside found in Left 4 Dead," says Lundeen.
"In Left 4 Dead 2, the players find themselves in the bayous, plantation ruins and parched cemeteries of the Deep South.
We wanted to convey the feeling of sweat and mosquitoes,
of Jack Daniels and flat pop. Naturally, we sent some team members on scouting trips to the area to gather photo
reference for texture and environment creation."
"The Deep South is rich in game play environments and charting the Survivors' path across these locales proved entertaining and artistically satisfying. Who wouldn't want to fight the hordes in a ruined
Plantation House, an old Sugar Refinery during a thunderstorm or the iconic setting of the French Quarter?
With the Deep South theme, New Orleans was an obvious choice for one of the campaigns."
Much like the edifices and alcoves of the actual Deep South, Left 4 Dead 2's environments had to have the same feel and communicate that feel to the player.
"Architecturally, we identified specific elements to create a formula for our vision of the city. These elements included the high ceilings necessary to dissipate the intense heat of the region and the
classic French Quarter balconies. The roof lines are dominated by gabled or hipped styles and most buildings in the area are only two or three stories tall."
"On our scouting trips, we found a plethora of small courtyards and narrow walkways between buildings that were not only a visually interesting feature of the area, but also provided great opportunities to
spawn in 'infecteds' to surprise and ambush the survivors in the game."
Giving environments the polish they need to bring everything together consisted of some out-of-the-box methods.
Things like flowing water and thunderstorms needed to be cleaned up, made believable and, of course, be done within the time that the dev team was given.
"In particular, the 'Swamp Fever' campaign required a highly optimized water rendering method to really sell the environment and still work within our technical constraints."
"Also, in order to help guide players through the swamps, we wanted to have the water generally flow down
the path to the end of the map in a way that was subtle enough to be natural, but clear enough to cue
the players to their intended route.
We implemented a new water shader that could have a unique flow direction and water speed at every point on the water surface. We used Houdini to generate flow maps
offline by first painting 2D flow directions manually. Another campaign that needed some additional effects work was
'Hard Rain.'"
"In this campaign, we wanted to create the sensation of being caught in a thunderstorm with driving rain. The particle effects
of the storm are made up of several thousand individual drops, impacts, mist
sprites, and screen effects. After the storm effects went into the game, we soon realized that the motionless trees were breaking the illusion of the powerful storm that we had worked so hard to create."
"To combat this, we added the ability to procedurally deform our tree models in a shader. Based on wind direction and strength, we use a low-frequency back-and-forth swaying motion combined with
higher-frequency motion to shake thinner branches and leaves. This procedural approach was significantly faster to implement than rigging all of our tree models for traditional skinned animation, which
was especially important given our
tight schedule."
