LOS ANGELES (AP) – Brendan Fraser is grappling with thin air.

Standing on a soundstage for “Looney Tunes: Back In Action,” Fraser pretends to wrestle the vainglorious Daffy Duck over a football-sized diamond that can transform humans into monkeys.

If “Back In Action” had been made just a few years ago, Fraser would have been fighting with a set of wires and levers attached to the gem. He would have pulled, the mechanism would have pulled back – and months later a team of frazzled animators would have pulled their hair out trying to match Daffy’s movements to both the actor and the jiggling prop.

Instead, there’s no there there – no wires, no levers, no diamond, no duck. Just an actor on an elaborate stage built to resemble an ancient temple, talking, playing and fighting with nothing at all.

Later, animators will plug in the drawn cartoon elements and a computer-animated “real” diamond, matching them to the live action.

“Back in Action,” directed by “Gremlins” filmmaker Joe Dante, stars Fraser as a security guard and Jenna Elfman as a studio executive who try to help Bugs Bunny and Daffy keep the magical diamond out of the hands of Steve Martin, who plays the evil, school-boyish head of ACME Corp.

In tone and technique, the hybrid of cartoon and real-life is a close cinematic relative to 1988’s “Who Framed Roger Rabbit” – but special effects have come a long way since then.

That Disney comedy featured a cast of cartoons who (with the help of complex, hidden machinery) smashed real plates on their heads, jabbed prop guns into the ribs of their human co-stars, and struggled to escape locked handcuffs. “Roger Rabbit” was so costly and difficult to make, however, it was nearly scrapped several times.

Today, much of the hassle of making such a film has been eliminated by computer-generated effects, which allow animators to duplicate tangible objects.

“What you hope for is just to interact with (the cartoons) in a way that appears as if it is seamless. That’s the biggest challenge,” said Fraser, who has practice opposite digital monsters in “The Mummy” movies and a psychotic animated simian in “Monkeybone.” “And it’s getting easier and easier to make these sorts of films because the technology is reinventing itself again and again and again.”

While rehearsing for 1997’s “George of the Jungle,” for instance, Fraser said he was “shackled” to very precise instructions about where to pet a space where post-production crews would insert a digital elephant.

“I raised my hand above its eyeline or something, and these guys had a conniption fit because it would cost another $85,000 if I raise my arm just a little bit.”

Now it’s cheaper and easier for animators to compensate for the tiny variations that used to add time, cost and stress to the moviemaking process.

How do they do it? “We cheat like mad,” laughed Eric Goldberg, who directed the animation for “Back in Action.” Usually, “cheating” means subtly shrinking the proportions of a character or adjusting the live-action image to match all the elements.

Both on the set and in post-production, the process that was once agonizing is now “whiz-bang,” Fraser said.

“We have more liberty,” he said. “That means you can work more quickly, which means you can maintain the freshness of the performance with fewer and fewer takes.”

If audiences are wowed by “Back In Action,” the simpler production process could mean an even bigger explosion of cartoon-reality movies than the one that followed “Roger Rabbit,” like 1992’s “Cool World” and 1996’s “Space Jam” (the last “Looney Tunes” movie, which also starred Michael Jordan.)

But does the reliance on computer animation take some of the magic out of the illusion? After all, part of the charm of seeing a cartoon pick up a real cigar is marveling at how they did it.

“That’s the chess game we play,” said Dean Cundey, the cinematographer who worked on both “Roger Rabbit” and “Back in Action.” “Typically, you always want to mix up the techniques, and never use one technique consistently throughout the movie because you’re always trying to misdirect the audience.”

On the “Monkey Island temple” set, Cundey pointed out a styrofoam “stone” passageway scattered with leaves. “We just did a sequence there where Bugs and Daffy have a little conversation and then they walk away. So we had guys with wires disturb the leaves around where the feet are. Then the wires are removed in the computers,” he said.

A similar effect could be done using digital leaves, but stirring prop leaves is a simple trick that may help blur the line between what the audience thinks is real or not. “Then we hope the animators will notice those kinds of details and put the characters in the right spots,” Cundey said.

Animators, meanwhile, worry about the actors and whether THEIR eyes will go to the right spots.

Technology allows the artists to stick Daffy pretty much wherever, but that doesn’t do much good if the actor is looking above the cartoon’s face or focusing on a point that’s too far away.

To help them gauge where to look and move, the actors rehearsed with Bruce Lanoil and Dave Barclay, two puppeteers who manipulated latex versions of Daffy and Bugs during rehearsals. They even mimicked the voices in rehearsal.

“I’m the human duck,” Lanoil says, grinning as he makes his Daffy puppet do an introductory wiggle. “I do a scene with you and you’re smiling and doing stuff you wouldn’t normally do if I wasn’t here – but there I am. Then I go away. Same thing: You know exactly what you did, and the camera captures that energy. … A little rubber a little love, and there you go.”

Elfman said she couldn’t have done the movie without them.

“I didn’t have a human co-star for three weeks,” she said. “And it’s hard doing high-stakes, high energy comedy with no partner … These puppeteers are funny, funny actors who really gave life to the dialogue and helped us establish our rhythm.”

Although the technical elements of making a cartoon-reality picture are getting easier, there were still some unexpected complications on “Back in Action,” including a late decision to scrap part of the ending and add outer-space hijinks between Bugs, Daffy and Marvin the Martian.

That required some fast work by the animators, along with sacrificing some of their existing work. But Goldberg, the animation director, said his team felt anything was worth it to make a Bugs Bunny movie.

“For those of us in animation,” he said, “this is like working with De Niro.”

AP-ES-11-12-03 1408EST