Bonecrusher, center, and Optimus Prime, right, do battle in "Transformers, " a DreamWorks film based on a cartoon based on a line of action figures.

There was never any hope that "Transformers," a film based on a cartoon based on a line of action figures, could be anything more than empty-headed spectacle. But what a spectacle it is!

Ideally designed for a young man whose favorite magazines are Popular Mechanics and Maxim, the new film channels the fanboy passion of director Michael Bay and producer Steven Spielberg into a slick, swift summertime smash.

And smash is the word for this hyperkinetic extravaganza, which begins with a Mideast robot attack that turns a U.S. military base to shrapnel and concludes with a free-for-all in downtown Los Angeles that batters the city to smithereens. The connective tissue in between — you know, story, characters, romantic subplots, all that dull stuff — gets short shrift, but the film's propulsive excitement, logic-shattering action and absurdist humor deflects all criticism.

It seems that Transformers, alien robot warriors that can fold down, Swiss Army knife-style, and pass for helicopters, fighter jets, and the entire 2009 General Motors product line of muscle cars, have come to earth in search of the Allspark, an obsidian cube that is the source of their power.

The heroic Autobots, led by Optimus Prime, and Megatron's evil Decepticons learn that the key to the Allspark's location lies with the unsuspecting Sam Witwicky (Shia LaBeouf), a likable nerd whose great-grandfather discovered it on a voyage to the Arctic Circle.

Being highly advanced products of a technological civilization far superior to our own, the robots settle their differences by blasting each other to splinters. Tyrese Gibson and Josh Duhamel run through the proceedings as dauntless servicemen who discover the chink in the aliens' armor.If you're making a film whose goal is simply high-megaton fun, Bay and Spielberg are the dream team. Heavy-artillery fetishist Bay shreds the envelope in terms of battle scenes, giving us man vs. machine and 'bot on 'bot duels of heroic scale and breakneck velocity.Spielberg is the gold standard in terms of technical sheen, passing along everything he learned about doomsday urban warfare from "War of the Worlds." You can see his perfectionism in the sequences where Cadillacs and Hummers transmorph into towering gladiators with sheet metal body armor. And he gives the project needed moments of humor, with a minor metallic rascal who tiptoes around the edges of the story only to be flattened, bashed and dismembered like a Meccano Wile E. Coyote.Screenwriters Roberto Orci and Alex Kurtzman, who learned their craft on TV's "Xena: Warrior Princess," salt the film with sly references to the Transformers cartoons (the catchphrase 'more than meets the eye' gets a good workout). And they supply plenty of colorful comic sideline characters, from Bernie Mac as the glad-handing used-car salesman who sells Sam a rusty Autobot-Camaro, to John Turturro as a government agent with a license to bug his eyes and shout at suspects.LaBeouf brings a winningly light touch to a role that mostly involved crouching and cringing amid heavy incoming flak, and Megan Fox adds admirable toughness to the part of his glamorous grease-monkey girlfriend.The film is overlong at 144 minutes — there's a sequence in which the Autobots visit Sam's home that clearly doesn't pull its weight — but it leaves you with a blissed-out exhaustion. As a camera-wielding teenaged extra shouts while recording one of the film's nonstop cataclysms, "This is 10 times cooler than 'Armageddon!"' — and how.