But because the animation department had committed to a 2D aesthetic, they couldn't simply move the camera around their 3D models of Charlie Brown and Snoopy. In fact, when they tried to, the characters didn't look like themselves. That's because, as lead character designer Sang Sung Lee discovered, Charles Schulz's hand-drawn characters only had five real facial positions in the comics and, to a lesser extent, the original TV specials: left, right, up, down, and a three-quarter frontal view.

The film's animators weren't the first people to run into this problem. When the character design team traveled to the Charles Schulz Museum in hopes of finding a three-dimensional reference among its collection of life-sized Peanuts statues, they were disappointed. A quick, 360 degree walk around any of the sculptures revealed that only one side looks right.

Snoopy was particularly challenging. “Because Sparky drew a side view and a front view differently, we had to make each camera angle customizable,” said Dunnigan. From the side, Charlie Brown's best pal has a Picasso look — both of his eyes end up on one side of his head. In a perfectly realized 3D animation of a character, a side view would show you just one eye -– but that wouldn't be Snoopy.

Similarly, Charlie Brown’s head distorts when he turns to the side. The ear moves down; the squiggle of hair on the front turns into a little downward curl. A single digital maquette for any of these characters would never work, especially if the team wanted to remain true to the Schulz aesthetic.

So they decided to do something unusual, creating software that would allow the animators to hit a button and introduce “character view." If Charlie Brown was walking toward the screen, then he turned left, an animator could turn the body but hit the character button to replace Charlie's head with the right side view. Sometimes, animators made adjustments on a frame-by-frame basis to avoid bizarre-looking distortions. Even the lighting had to be custom-built.

There was one bright spot in all this: Animators realized as they were poring over the comic strips that the characters, with the exception of Snoopy, pretty much all shared the same body.