CGSociety has an interview with Jeremy Bennet, Character Designer, and Randy Lundeen, Environment Designer, who both worked on Left 4 Dead 2. In the interview they discuss the design of the environment, throughout the Southeast, and get into the various details of the tiny effects that contribute not only to the visual effects but to the subtle player psychology of the game.
“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.””
