Her role, but did she want it?

It can be strange, meeting for the first time someone you have just recently seen naked. Such is the case with the 24-year-old French actress Ludivine Sagnier. As a troubled, tempestuous girl in “Swimming Pool,” prone to sunbathing topless and having lusty nighttime encounters with strangers, her character is like a fantasy-league version of French women. Veering wildly between steely forthrightness and wounded impetuousness, she proves a formidable match for the icy reserve of her co-star, veteran beauty Charlotte Rampling.

That’s why the petite, quiet woman who materializes one afternoon at a table at the Sunset Strip restaurant Asia de Cuba comes as all the more a shock. From her turn in “Swimming Pool,” her third collaboration with writer-director Francois Ozon, one half expects a boisterous man-eater, mouthy and bossy, and certainly not the self-effacing little sparrow who takes a seat for a quick lunch. Dressed in an outfit of fashionable fabrics provocatively cut, she quickly reveals an understated but bewitching charm.

Raised in the Paris suburbs, she began taking acting lessons at 8, headed to a three-year drama school at 15, and eschewed university in favor of a traveling theater production. Along the way she did a handful of television shows and movies, most of which she now discounts as “sleazy,” “small” or “not interesting.”

Ozon first contacted her after seeing her in a short film. He had already made a splash on the festival circuit with his debut feature, “Sitcom,” and was editing his second, “Criminal Lovers,” as he began to cast for his third, “Water Drops on Burning Rocks.”

Although Ozon was initially concerned that she was too young for the part, once they met she won him over. That film, which Sagnier describes as “a dark story with a light point of view,” was extremely stylized, making the bold naturalism of Ozon’s next project, “Under the Sand” (starring Rampling) all the more surprising. Ozon worked again with Sagnier on the jewel-box artifice of “8 Women,” which garnered her recognition throughout Europe.

In “Swimming Pool” the director now seems to be reconciling the two poles of his work, using the two actresses as representatives of conflicting impulses.

Casting her relationship with Ozon as a “Pygmalion” tale with overtones of Josef von Sternberg, Sagnier says, “As we’ve done two movies together, I belong to his tools of creation. The idea of a creature who sees her identity stolen by her creator, who feels totally dependent on someone else’s imagination and is lost otherwise, I identify with, especially when I’m working with Francois. I always feel he’s going to steal my emotions from me.”

Even though Ozon wrote the role of Julie in “Swimming Pool” with Sagnier in mind, she wasn’t sure at first she wanted to take the part. “The thing is,” she continues, “ ‘8 Women’ was very successful. We promoted it all around the world, and every time you arrive in a city, the producer takes you to the best restaurant. And I love to eat and to drink. I had the greatest time, but I had put on a lot of weight.”

“When Francois asked me to do the part, it was like, ‘OK, but I can’t stop eating, so I can’t do it. I don’t feel like showing my body.’ He said, ‘We’ll get you a trainer and you should work out.’ So that’s what I did.”

Ozon says she took to the challenge. “After being such a tomboy in ‘8 Women’ I wanted to give her the opportunity to be glamorous, to be sexy and to show another part of her talent,” he says. “I knew she had it in her, but it was a real challenge for her to play such a girl, because she’s not like that in real life. But she loved to work on her body, to have a coach, to work on her form before shooting. When she arrived on the set, she was very proud of her body and very exhibitionist, which was great for the character, who has no fear of showing her body.”

In scenes where she slinks around the pool of a house in the south of France, Sagnier’s pouty petulance perhaps sometimes comes across as a little too real.

“Friction is the way Francois and I work together,” she says. “We’re always struggling. In this case everything I would offer, he would turn it down, so I would feel vulnerable and dependent on his will. But that was only for the character. After we stopped shooting, he went back to the sweet friend I had.”

Ozon downplays any troubles between them as simply part of their working method. “I think maybe now we are too close.” Sagnier arrived in Los Angeles directly from Australia, where she has been shooting the role of Tinkerbelle for director P.J. Hogan’s live-action adaptation of “Peter Pan.” Working almost entirely with a second-unit crew handling photography for effects scenes, usually without other actors present, Sagnier’s part will be enhanced by digital trickery.

“At the beginning I was hired only as a double for CGI,” or computer-generated imagery. “They wanted only a digital image of Tinkerbelle. The part is mute, so I had to express myself more like a mime than an actress, completely different from anything I’ve done before. I made a really clownish character, and I think they loved it and realized they couldn’t do it with just a computer image.” Though the role is a decided departure from her collaborations with Ozon, she was excited, and perhaps a little relieved, by the change. “I jumped on the part. I’d been feeling so dirty doing all the things as Julie ... and suddenly the remedy appeared -- we’re going to wash away your sins, girl! Have fun, take off and play the fairy. Come away to Neverland!”