Don’t be fooled by the previews for “Body Shots.” Its tale of one night in the lives of eight L.A. twentysomethings is not the ’90s equivalent of “Saturday Night Fever” and “The Breakfast Club.” While the movie does embrace this generation’s casual approach to all things sexual, and its underlying feeling of desperation, it doesn’t capture either in any significant sense.

The first half starts off as a variation on the much better “Swingers.” Four guys and four girls get ready for a long night of partying on the town. They drink and joke and talk about the differences between the sexes and the realities of dating in the ’90s. Like Doug Liman’s earlier comedy, this one also features an obnoxious goofball named Trent (played by “Swingers’” own Ron Livingston), as well as the usual assortment of under-30 types.

It doesn’t take long to figure out who’s looking to hook up with whom. Rick (Sean Patrick Flannery) and Jane (Amanda Peet) are lawyers trying to negotiate the waters of their burgeoning relationship. Michael (Jerry O’Connell) is a pro football stud who’s taken with flirtatious, young Sara (Tara Reid). Shawn (Brad Rowe) is a soft-spoken sensitive-guy type. Emma (Sybil Temchen) is his female counterpart, and roommate/waitress Whitney (Emily Proctor) is a buxom blond Southern belle.

Their commentary, much of it delivered by the characters breaking down the fourth wall and expressing their feelings directly to the camera, is often hilarious. The sight of the outrageous Trent dressed in golf attire at a posh L.A. nightclub is a genuinely funny sight, as are his various entanglements, from being escorted about town in an ambulance to a late-night romp with a “Bond girl.”

Unfortunately, the Generation X humor is undercut by a dramatic development that turns the film into overwrought melodrama. While much of the movie is presumably comedy, there’s an abrupt shift in the middle that switches the film’s attention to a series of ambiguous events that may have led up to a date rape.

The transition is more than the film can handle. The first half, although amusing enough, derives its laughs from other recent twentysomething pictures such as “Swingers” and “Go.” The last half is derivative of too many television movies of the week. Although director Michael Cristofer intends to make a somber statement about extreme lifestyles devoid of lasting intimacy, the project comes off as half-baked.

Because it’s not designed to be a real comedy, the movie’s not as funny as its predecessors. And since the juxtaposition of genres is merely jarring, it’s also not as dramatic as it would like to be considered. The cast is uniformly earnest and believable, but the screenplay’s manipulative change of events make the film’s claim to generation glories seem sorely pretentious.

“Body Shots” has lots of hot faces, a contemporary outlook and a few credible scenes of angst and amusement. Unfortunately, unlike the other movies advertised in the trailer, it forgets that if a film is to connect to its generation, it also needs to be its own complete experience.

* MPAA rating: R, for language and sexuality.

'Body Shots'

Sean Patrick Flanery: Rick

Jerry O'Connell: Michael

Amanda Peet: Jane

Tara Reid: Sara

Ron Livingston: Trent

Emily Procter: Whitney

Brad Rowe: Shawn

Sybil Temchen: Emma

A New Line Cinema presentation. Director Michael Cristofer. Producer Harry Colomby. Executive producer Michael Keaton. Executive producers Guy Riedel, Michael De Luca, Lynn Harris. Screenplay by David McKenna. Cinematographer Rodrigo Garcia. Editor Eric Sears. Music Mark Isham. Costumes Carolyn Leigh Greco. Production designer David J. Bomba. Set designer Daniel Bradford. Art director John R. Jensen. Set decorator Kathy Lucas. Running time: 1 hour, 42 minutes.