Have we reached critical mass for computer-animated movies about fantasy worlds where everything is a jokey parallel to our own? It’s underwater, but it’s just like New York, so the crosswalk signs say “Swim” and “Don’t Swim”! Or it’s the fairy tale world, but it’s just like ours, so there are fast-food joints with names that sound like ours but with fairy tale puns! I believe we have “The Flintstones” to blame for this epidemic, among the many other things we have “The Flintstones” to blame for. (The gradual decline of civilization, for example.)

It’s a problem because some writers and directors are relying on the jokes to propel their movies, rather than devising interesting stories or creating lovable characters. “Shark Tale” marked the low point for computer-animation, and though “Robots” is a bounce back, it’s not a very high bounce. Once again, we’re given a tour of the town — this time it’s a city with no organic life, only robots! — and once again, we see robot dogs being warned by robot fire hydrants not to pee on them. Har!

(Of course, if there’s no organic life, I’m not sure why there’s even water, let alone hydrants. And how come the hydrant can talk but the dog can’t? And what would be the point of building a fire hydrant that’s also a robot? Why not just build a hydrant? They’re not supposed to get up and walk around, you know. That would actually defeat the purpose of a fire hydrant, which should always be where you left it, not ambling around scolding dogs. I’m just sayin’.)

Like I said, you don’t notice this kind of visual punnery if the movie is great, or if the jokes are particularly clever. In “Monsters Inc.,” it felt like part of the film’s overall vibrance and good cheer to see the monster-influenced world the characters lived in. In “Robots,” it feels like they sat around thinking of robot-world gags and neglected everything else.

It doesn’t help that Robin Williams, master of creaky impressions and manic, substance-free ad-libbing, plays one of the lead roles. Asking him to recapture the magic of what he did in “Aladdin” 13 years ago winds up looking like all he did was, um, try to recapture what he did 13 years ago. Which is more sad than funny, really.

“Robots,” directed by Chris Wedge (“Ice Age”), is about an idealistic young robot named Rodney Copperbottom (voice of Ewan McGregor) who leaves his hometown of Rivettown and heads to the big city of Robot City to become an inventor. He wants to work for Mr. Big Weld (Mel Brooks), a major robot entrepreneur whose populist ideas and open-door policy give hope to young tykes like Rodney.

But Big Weld has been forced out of his own company, with Phineas T. Ratchet (Greg Kinnear) in as the sleek, handsome new CEO. Ratchet’s plan is to stop making spare parts for the city’s robots and force them to buy expensive “upgrades” instead. The poorer robots who can’t afford such things? They become scrap metal — which is just great for Ratchet’s evil mother Madame Gasket (Jim Broadbent), who melts scrap metal down and re-uses it for profit. That can opener you’re using? It was your homeless cousin just yesterday.

Robin Williams is the voice of Fender, a robot who lives with other unemployed, shiftless robots in a flophouse. They’re all falling apart, and they’re thrilled when Rodney — a born tinkerer and fix-it man — arrives on the scene and starts repairing them, free of charge. This doesn’t sit well with Phineas T. Ratchet, of course, because if someone’s fixing robots, they won’t need spare parts OR upgrades. Rodney represents Canada’s national health care program, and Phineas is the HMO. (As always, it’s the lefties making the movies.)

The screenplay, by perennial jokesters Lowell Ganz and Babaloo Mandel — think “City Slickers,” “Multiplicity” and TV’s “Happy Days” — has some extremely clever bits that should not be overlooked, but it has more mediocre ones.

In addition, there are a few amazing action sequences set in the mechanical robot world that rival anything we’ve ever seen, at least in terms of technical proficiency and state-of-the-art wonderment. But where are the characters to make it all MEAN something? Watching strangers on a roller coaster isn’t nearly as much fun as watching your friends.

C+ (1 hr., 31 min.; PG, some crude humor, mild innuendo.)