Entertainment

Meet Peter Parkour

Between 2002 and 2007, the trilogy of Spider-Man films starring Tobey Maguire and directed by Sam Raimi were the most successful superhero franchise in the history of cinema. Not only did they gross a combined $2.5 billion worldwide at the box office, but the first two films were critical darlings that garnered rafts of awards and nominations.

So why bother rebooting a classic?

Because the stunts sucked.

“They looked ridiculous at times, and so much of it relied on CGI. I didn’t particularly enjoy them,” says legendary stuntman Vic Armstrong, who earned his stripes taking the fall for Harrison Ford in “Indiana Jones” and Christopher Reeve in “Superman.”

So Vic and his brother, Andy, signed on to “The Amazing Spider-Man,” out July 3, as second unit director and stunt coordinator, respectively. Their goal: Make Spidey’s web-assisted soaring more realistic.

“When Sony approached me about doing this movie,” Andy tells The Post, “I said I’d love to really revisit the style and look of the picture, and try and make it very organic and make it feel like a real man swinging.”

The producers were doubtful that could be achieved after past failures, Andy recalls, but he wasn’t deterred. To figure out just where previous Spider-Mans had gone awry, Andy brought in an elite gymnast and videotaped him swinging about from all angles.

Watching the videos, “I immediately realized what was wrong,” he says. “If you look at the old movies . . . he swings down at a constant speed, gets to the bottom and then changes and goes up, and it’s all constant.”

The gymnast footage demonstrated that the downward swing should be fast and violent, with the man pulling three G’s at the bottom of his arc. The upward trajectory, meanwhile, should get slower and slower until Spidey reaches “negative gravity” and is ready to start his next web swing.

“Once we had that, as simple and obvious as it sounds, then we started building devices that could swing a man over a continued distance using that principle,” Andy Armstrong says.

Stunts are something of the family business for the Armstrongs. Older brother Vic first got into the industry in the ’60s as a steeplechase jockey and accomplished equestrian who fell into helping out with horses on film and TV sets. With his riding skills and daredevil nature, he quickly became an in-demand stuntman. Now 65, he prefers directing the action rather than being in it. He recounts some of his greatest tales in “The True Adventures of the World’s Greatest Stuntman,” issued in a paperback edition this month.

Andy, 58, got in on the action in 1973 when Vic needed a motorcycle rider on a TV series called “The Zoo Gang.” The brothers have since worked on numerous pictures together, from “Thor” to “Rambo III.”

“We don’t really disagree that much,” Vic says.

He and his wife, Wendy Leech, even met doing stunts: On 1978’s “Superman,” he was a stunt double for Christopher Reeve’s Superman and she for Margot Kidder’s Lois Lane. Their daughter and two sons all work in stunts and were on “Spider-Man,” as were their son-in-law and Andy’s son.

No wonder star Andrew Garfield, who plays Peter Parker/Spider-Man, has said that working with the stunt team was like “being part of a tribe.”

Andy speaks of Garfield with fatherly affection, as he describes how the 28-year-old actor transformed from a “skinny kid” with “terrible posture” to an all-muscle machine capable of amazing athletic feats, á la a young Bruce Lee.

“We stripped him down to nothing,” he says of Garfield’s intense training regimen and diet, “and then we built him back up through nothing but protein. None of it was fake bulk — he was still lean.”

While it’s a common Hollywood p.r. line these days to say an actor did many of the stunts himself, with Garfield, Andy says, it’s no bull. “Not many actors actually get on a nitrogen air ratchet or get on a winch — Andrew rode all that stuff.”

Garfield’s transformation — and the stunt department’s high-tech rigging and experimentation — took place in a giant, 25,000-square-foot Los Angeles warehouse, miles away from the Sony lot. The stunt department took it over months before shooting began.

“We shut the doors and sort of no one knew what we were doing in there,” Andy recalls. Entire action scenes were tested and taped in the warehouse on mock sets, so that when it came time to do them for real, everything was set.

“We had effectively done the entire film in the warehouse,” says Andy.

They were able to achieve the realistic swinging motions using a high-powered, high-speed winch that could pull a hanging man forward while an operator on the ground could accelerate him by hand and “crack the whip” to rapidly change his direction and achieve the desired motion. At times, Vic estimates that Garfield or one of his doubles got as high as 120 feet in the air on such rigs and then swooped down to just 10 feet above the ground, traveling at speeds of 50 to 60 miles an hour.

“You wouldn’t want to hit anything at that speed, that’s for sure,” Andy says.

In the finished film, when Spider-Man goes flying through the air, “it really is a real person, it’s not a computerized person,” says Vic. In some cases, of course, the man was shot flying in a studio against a green-screen background that’s later replaced with a cityscape. But the motion is real — and sometimes the whole thing is.

Andy talks excitedly of retrofitting an old fire truck so that a stuntman could hang from a beam behind it and be “puppeteer-ed” from left to right as the truck drove through New York City traffic at 30 or 40 mph. “I had no idea whether it would work or not,” Andy recalls. “When you saw the footage, it just took your breath away. You see a real man swishing over cars and they’re going at real speed.”

Elsewhere, the man running through the city and climbing up buildings is real. The Armstrongs were inspired by watching dozen of videos of parkour, a rogue athletic discipline where practitioners treat the urban environment like an extreme obstacle course, vigorously running, jumping, and climbing over a city. One of Garfield’s stunt doubles was a dedicated parkour expert, and the actor also trained in the practice himself. “The parkour people are super human,” Vic says.

The film spent several weeks shooting on location in New York. The first time the police chase Spider-Man in full superhero regalia, he swings under the Riverside Drive Viaduct to get away from them. It took a week to shoot the sequence, with all filming done at night and traffic on the bridge stopped entirely. Stunt drivers drove cars across the bridge as both Garfield and his stunt doubles swung below them.

Other times, New York came to them. For a complex fight scene that takes place on the subway as Peter Parker is just beginning to learn to control his newfound super powers, a real subway car was brought onto a soundstage at Sony studios in Los Angeles. Garfield was harnessed to the ceiling using a shoelace-thin, ultra-strong line known as Tech 12. Images of the Williamsburg Bridge were shot on location, but actual shots where the actors and stuntmen interact with the bridge were done on a set piece in the studio.

Spider-Man’s swinging wasn’t the only thing the Armstrongs completely reinvented. The brothers also created an ultra-thin, buckle-less harness for Garfield and his double using high-tech, man-made fibers and a special, ultra-strong Velcro used by NASA. The harness not only needed to support a 150-pound man pulling three G’s of force, “It had to go underneath that skintight suit without any visible panty lines,” Vic says.

Yes, panty lines come into play when shooting big budget action flicks.

“The stunt business is really such a mistaken industry, people get it mixed up with daredevils,” Andy says. “Our business is really about making things that look as dangerous as possible to as safe and as repeatable as possible.”

Sultans of swing!

Harness: The Armstrongs developed a harness thin enough to fit under the skin-tight Spidey costume without being noticed. It incorporated ultra-strong Velcro used by NASA to contain the force of a man hitting three G’s at the bottom of a web swing.

Harness cable: The production used ultra-thin Tech 12 cable to support Garfield’s 150-pound frame during all stuntwork.

Suit: Costume designer Kym Barrett was inspired by athletes at the Winter Olympics to create a stretchy costume that could be handmade by a tech-savvy kid.

Web action: Andy Armstrong analyzed footage of gymnasts to make Spidey’s swings look more realistic. Instead of swinging at a constant speed, a high-powered winch “cracks the whip” to draw Garfield down quickly, then decelerate him on the way up. Top speed of a winch-assisted swing is more than 50 mph.

Bridge: The production spent a week shooting this scene on location at night under the Riverside Drive Viaduct, an eight-block stretch of latticed-steel elevated highway that starts at 12th Avenue and 127th Street. The ornate onramp was built in 1900 at a time when public structures were designed with deliberate grandeur.