The directors of ‘The Angry Birds Movie’ on turning an app into a film

Fergal Reilly knows how absurd it is that an “Angry Birds” movie exists.

“It’s almost a joke when you hear it pitched as the logline,” the animator says.

And yet it wasn’t such a joke that he didn’t turn down the chance to make it his directorial debut. Reilly — who’s worked for years, mainly as a storyboard artist, on the likes of “Cloudy with a Chance of Meatballs” and “Hotel Transylvania” — helmed the app game-turned-film with Clay Kaytis, a Disney vet also graduating to top boss. (It’s standard, they say, for animated films to have two directors, given how much there needs to be approved.)

The two did and didn’t have their work cut out for them. The simple set-up — flightless birds being slingshotted into evil green pigs — had to become an origin story, but that was taken care of by the script by “Simpsons” writer Jon Vitti. And the birds’ various designs were right there in the game.

What they had to add was animation that reflected each character’s personality, and create a whole new world whose every inch is filled with sight gags and funny bits of business.

“I’m always pleased when people say it has a ‘Looney Tunes’ feel. It’s like, ‘Okay, I did my job,’” Kaytis, whose credits include “Tangled” and “Frozen,” tells us. One perk of animation over live-action is you can always add stuff when you think of it. “We were always looking at the background and the sides for jokes — a sign on the wall, anything that can make it visually funnier.

“For me, the fun of animation is in design. Making animation that feels like real life is kind of a waste of energy.”

Vitti’s script provided a solid foundation. “Sometimes when you read animated scripts the characters start to blend into each other,” Reilly explains. Vitti’s script was different. “He always had a unique take on each character. He had a voice in his head and he was able to write that voice. That helped us when we were casting it and when were trying out bits of business in the storyboarding stage.”

Jokes, of course, aren’t the main thing people expect from “The Angry Birds Movie.” Reilly and Kaytis had to deliver some flying-bird-on-pig action. That’s mostly pushed off to the climax.

“As fans of the game, we thought of that part as the desert,” Kaytis says. “That was the stuff we did towards the end of production. So we had our vegetables and our meat, dealing with characters and relationships. Then we let loose on that final section — let loose with camerawork.”

Still, they didn’t think of this section as just about thrills. “We decided to design the action so it was around character or around a comedic gag, rather than action for the sake of action,” explains Reilly. One of his past credits is “Spider-Man 2,” whose set pieces were part live-action, part digital animation. “We were doing these complex action sequences with a lot of kinetics and dynamic camera movement and cutting.”

In fact, Reilly argues, directing animation can be as complex as directing live-action, maybe moreso.

“It’s like creating a movie in slow-motion,” Reilly says. “You control every single facet of the image. You’re literally building it pixel-by-pixel. It many ways it’s more complex than live-action, because you have to have all the understanding of story and character, but you also have to have the technical understanding of how to create the image. You’re creating every single image from scratch.”

“It’s really just an extension of what we’ve being doing for years. It’s just on a larger scale,” Kaytis adds. “Animated films require so much decision-making: you have to make sure every blade of grass looks right, that the fur on the birds looks right. It’s nice to have a movie with your fingerprints on it.”

Follow Matt Prigge on Twitter @mattprigge