Let’s get it out of the way: If you’re going to see “Life of Pi,” you must see it in 3-D.

If you saw “Avatar” or “Hugo” in 2-D, you saw flatter versions of those movies. But if you see “Life of Pi” in 2-D, you will not be seeing “Life of Pi.” It would be like a comic book with words but no pictures. Ang Lee, in his best work since “Crouching Tiger, Hidden Dragon,” makes 3-D integral to the storytelling in this miracle of a film.

Lee’s film is based on the bestselling 2002 novel by Yann Martel, which often has been called unfilmable. Lee answers that challenge by turning “Life of Pi” into one of the most filmic works of art ever made. By coincidence, “Life of Pi” arrives a few weeks after another visionary adaptation of an “unfilmable” novel, “Cloud Atlas,” but where “Cloud Atlas” is a complex anthology, “Life of Pi” tells a very simple story.