The computer-animated Shrek opens with a scene that states the movie's intent as clear as day -- the title character, a green ogre, rips a page out of a fairytale book and (offscreen) wipes his butt with it.

Shrek aims to be the anti-fairytale -- a spoof that blows apart the conventions of the Disney-fied "happily ever after" cartoon, poking fun at such Disney icons as Snow White, Pinocchio, the Three Little Pigs and "It's a Small World" along the way.

And, with its saturation bombing of pop-culture jokes (Macarena, "Riverdance," The Matrix) and the inspired semi-improvised voice work of Eddie Murphy, Shrek achieves its goal for much of its run. But the pull of fairytale myth is too strong, and Shrek eventually falls into line as a solid, if offbeat, fairytale story.

Shrek (voiced by Myers) lives alone in a swamp, employing personal habits that ensure his solitude -- mud showers, fish-killing flatulence and making candles from his earwax. But his privacy is shattered when a host of fairytale creatures show up in his swamp, his dining room and even (in the case of a certain nightgown-clad wolf) in his bed. Seems they were all evicted from the kingdom of Duloc by Lord Farquaad (John Lithgow), a ruler with a major Napoleon complex.

Shrek makes a deal with Farquaad -- he gets his swamp back if he rescues Farquaad's intended bride, the lovely Princess Fiona (Cameron Diaz), from a dragon-protected castle. Shrek, aided by a chatty donkey (hilariously voiced by Eddie Murphy), does rescue Fiona -- who is a tad too eager to do the "true love's first kiss" thing, for reasons that become apparent later.

The script (credited to four writers, led by Aladdin co-writers Ted Elliott and Terry Rossio) is peppered with the best fairytale spoofs since Jay Ward's "Fractured Fairy Tales." The best may be when Fiona wakes up and starts singing to a bluebird, and hits a high note that makes the little feathered friend explode. Also prevalent are a slew of anti-Disney in-jokes -- and if you think Farquaad has a complex, how about Jeffrey Katzenberg, the ex-Disney exec who (as DreamWorks co-founder and one of the three credited producers) oversaw the movie?

The animation, produced by the Pacific Data Images crew that made Antz and guided by co-directors Andrew Adamson and Vicky Jenson, is first-rate. The textures are detailed, the movements are realistic and the three-dimensional feel even improves on the humor -- you may think you've seen every good Matrix parody, but you haven't until you see this.

In the final third, Shrek gets all warm and fuzzy and becomes the fairytale movie it had so successfully skewered. For all the snarky attitude, Shrek eventually finds the lure of "happily ever after" even stronger than an ogre's flatulence.