CANNES, France — One of the great pleasures of this year’s Cannes Film Festival has been a momentary close-up on Julianne Moore’s face in David Cronenberg’s “Maps to the Stars.”

It comes when her character, a desperate and superficial actress, learns that the role she covets has opened up because her rival’s young son has died. A flicker of utter glee flits over Moore’s face so quickly and subtly before it’s replaced by a mask of insincere sorrow. It takes a great actress like Moore to play one as shallow as Havana Segrand.

Moore’s performance in “Maps to the Stars” has been one of the most acclaimed at the Cannes Film Festival, where Cronenberg’s gloriously dark satire of an incestuous, cynical Hollywood premiered earlier in the week. Written by Bruce Wagner and starring Mia Wasikowska, John Cusack and Robert Pattinson, “Maps to the Stars” features cutthroat movie business insiders and celebrity-obsessed aspirants in Los Angeles who are, as Cronenberg said, “desperate to exist.”

“She’s very touching to me,” Moore said in an interview of her character. “She’s such a lost soul, terribly adolescent at best. Her desire to be seen and to be acknowledged and to be validated — all of that externalization of her inner need is kind of heartbreaking.”

The irony is also that Moore could hardly be more different than her character. For decades now, the 53-year-old actress has been an ever-shifting, scarlet-haired force of naturalism. Though her range across films like “Short Cuts,” “Vanya on 42nd Street,” “The Big Lebowski,” “Boogie Nights” and “The Kids Are All Right” varies widely, Moore has always been an actress whose art is her apparent effortlessness. Plus, she has one of the best laughs in show business: a head-thrown-back, squinty-eyed, totally infectious cackle.

Does she grant that she’s more level-headed than her character?

“I think so. I hope so,” says Moore. “You have to have a fairly realistic assessment of who you are, what your abilities are and where you are in your career and your age. Hopefully I’ve never been that extreme.”

“There are plenty of times where I’ve looked at stuff and gone, like, ‘I can’t do that,’” says Moore. “I don’t look at things and feel like, ‘I can do everything.’ I can’t. But if I have a connection and a response to it, I tend to be aware of what I’m capable of and what I’m not.”