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Animating snow is no easy feat, as the creators of Disney’s “Frozen” discovered sort of late in the process: do it wrong and it winds up looking like “Styrofoam packing peanuts,” as Chris Buck, a director of the movie, put it.

Creating Olaf the talking snowman was more fun, at least in terms of drawing, added Jennifer Lee, the screenwriter and co-director. But finding his personality was a challenge: “I remember one of our story editors just saying, ‘How does snow think?’” she recalled. “And we’re like, ‘it’s very pure.’ O.K., let’s start there.”

There were other challenges in the musical, a genre that Disney hasn’t done, at least not to this degree and with human characters, in many years. John Lasseter, the head of Disney and Pixar animation, helped guide each scene, from the acting to the animation. “He pushed them to really work on the breathing — how do singers breathe when they sing?” Mr. Buck said.

Idina Menzel, who voices Elsa, the older sister in the movie, and a veteran theater performer herself, visited the animators to explain singers’ complicated breathwork. But the animators found it worked differently once the characters were dressed in their royal gowns.

“We had to go a little bit broader with the breathing for it to show up,” Mr. Buck said.

“And how you breathe differently when you’re emotional in the song, when you’re being moved,” Ms. Lee added. “The animators adjusted for that, too, “so you could feel what Elsa was going through, from small to very broad.”