Ed Catmull's office could be a window into the brain of Pixar.

Catmull, president of Walt Disney and Pixar Animation Studios, sits at a round wooden table at Pixar's whimsical headquarters in Emeryville, California. To his right, the walls are filled with items that inspire creativity. There's a plaster mold of his left hand: the star of the first computer-animated short he made in 1972 as a graduate student at the University of Utah. There are also toys galore, a collection of old watches, and trinkets that look like they were picked up at souvenir stands around the world.

To his left, though, it's all business: a dual-monitor Mac, two elegant gray armchairs and a row of framed, understated drawings from Pixar movies, featuring friends like Woody and Buzz Lightyear.

The room is a metaphorical manifestation of the cerebral hemispheres -- fitting for the co-founder of a studio that melded computer algorithms with art in a way no one had ever done before.

Pixar

Twenty years ago this month, Pixar ushered in a new era in cinema with "Toy Story," the first full-length feature film created entirely with computers. Critics praised the animated film, with Roger Ebert calling it "a visionary roller-coaster ride of a movie."

What stands out for Catmull is that nearly all of the critics devoted only a sentence or two to its breakthrough computer animation. "The rest of the review was about the movie itself," Catmull recalls. "I took immense pride in that."

In the past two decades, Pixar has become a celebrated art house, with other groundbreaking films to its credit, including "Monsters, Inc.," "Up," "Wall-E" and, most recently, "Inside Out." (Pixar will release its newest film, "The Good Dinosaur," later this month.) But Pixar's achievement hasn't just been a game changer for animation; it's been course-altering for all of film.

"Toy Story" wouldn't have been possible without groundbreaking software from Pixar. Called RenderMan, the program let animators create 3D scenes that were photorealistic. The idea: Generate, or "render," images that look so real you could put them in a movie alongside live-action footage -- and no one could tell the difference.

Pixar, which licenses RenderMan to other film studios, boasts that 19 of the last 21 Academy Award winners for visual effects used the software. They include "Titanic," the "Lord of the Rings" trilogy and "Avatar."

But film experts point to three movies from the mid-'90s that signaled the sea change for digital moviemaking: "Toy Story," "Jurassic Park" and "Terminator 2." RenderMan had a part in all of them.

"Before those three movies, the idea of making a movie with a computer was ridiculous," says Tom Sito, chair of animation at the USC School of Cinematic Arts. "After those movies, the idea of making a movie without a computer was ridiculous."

Still light-years away

Things might have turned out very differently.

In 1975, Catmull hired Alvy Ray Smith, a charismatic computer graphics pioneer from New Mexico, to join his new Computer Graphics Lab at the New York Institute of Technology. The lab was based on Long Island, not far from the environs of Jay Gatsby, the fictional millionaire from "The Great Gatsby." Catmull and Smith's research was bankrolled by their own eccentric multimillionaire, the institute's president, Alex Shure. From the beginning, Catmull and Smith had a specific goal: Make the first computer-animated feature.

Deborah Coleman/Pixar

If there's one striking thing about how Pixar came to be, it's that there was always a rich guy keeping the dream alive. After Shure, it was George Lucas, fresh from the success of "Star Wars" in 1977. Lucas poached the team to start a computer division at his production studio, Lucasfilm. Then Steve Jobs -- down and out after being ousted as CEO of Apple -- stepped into the picture as he was looking for a comeback. Jobs bought the team from Lucasfilm for $5 million. Catmull, Smith and Jobs co-founded Pixar in February 1986.

Back then, Pixar wasn't in the movie business. Instead, the company was hawking computers specifically for visual effects. Pixar created short films -- and honed its animation skills in the process -- to show potential customers what its computers could do.

But the company was sinking. The technology just wasn't advanced enough to produce full-length films. During the early years, Jobs put in $50 million, a significant chunk of his fortune at the time, to keep it afloat. "The only reason we didn't officially fail was because Steve didn't want to be embarrassed," recalls Smith.

When it came to making short films, though, the team was world-class. There were two reasons for that success. First, Catmull and Smith put John Lasseter -- a young, visionary animator the company picked up while still with Lucasfilm -- in charge of Pixar's creative process. (Where the office of Pixar's technical maestro Catmull has only one wall of toys, Lasseter's bursts at the seams with them.)

The other reason was RenderMan.

Pixar developed the software with one simple goal: Create images good enough for Lucasfilm to use, says Catmull. At the time, animators could only cram about 500,000 polygons onto the screen when creating a scene. In computer graphics, a polygon is a flat, two-dimensional object drawn with at least three sides. Adding more polygons lets artists create more realistic-seeming 3D objects.

Courtesy Pixar

Catmull's goal was 80 million polygons.

"Nothing could really handle the complexity of what we were trying to do," says Rob Cook, one of the original authors of RenderMan. "We were setting the bar."

They were so successful that in 2001, the Academy of Motion Picture Arts and Sciences' board of governors honored Cook, Catmull and Pixar engineer Loren Carpenter with an Academy Award of Merit "for significant advancements to the field of motion picture rendering." It was the first Oscar awarded to a software package.

"The thinking was, 'If we could control this, we could make animated movies the way we think they should be made,'" says Jerry Beck, a historian of animated films.

The big break

Back in Catmull's office, we stare at my iPad. I've asked him to take me through "Tin Toy," a 1988 Pixar short about a marching-band toy trying to escape a slobbering baby. "You look at it now and it looks really crude," he says. (Even cruder than normal. We're watching the short on YouTube, and Catmull, ever the perfectionist, remarks that the upload quality has degraded the picture.)

He rewinds the video to a scene of the baby waving. The animators deliberately blurred his hand in motion, so it would look more natural to the human eye. That, he said, was a breakthrough.

For sure, "Tin Toy" was a milestone: It won the first Academy Award for a computer-animated short. But its role in movie history is bigger than that. "Tin Toy" inspired that other Pixar movie about toys.

FRED PROUSER/Reuters/Corbis

When Pixar started pitching projects, Catmull didn't think the team was capable of creating a whole movie. Instead, he pitched a 30-minute TV show. And because it had to do with toys, the show would be a Christmas special. Peter Schneider, the Walt Disney producer responsible for hits like "The Little Mermaid" and "Beauty and the Beast," thought better.

"If you can do a half-hour, you can do 70 minutes," Catmull recalls Schneider saying. "So I thought about it for about one nanosecond -- like, 'Yeah, you're right.'"

"Toy Story" was released November 22, 1995.

"Nothing could really handle the complexity of what we were trying to do. We were setting the bar." Rob Cook, co-author of RenderMan software

It was the first of many milestones. Pixar's CTO Steve May says RenderMan delivered another breakthrough for the 2001 film "Monsters, Inc." when it allowed animators to render individual strands of Sulley's blue hair. Chris Ford, Pixar's RenderMan business director, thinks the studio will raise the bar again with the water scenes in "Finding Dory," the "Finding Nemo" sequel due out in 2016.

The release of "Toy Story" also fulfilled an early goal of the team that developed the software. "We wanted to make it so people everywhere could use it," says Pat Hanrahan, the former Pixar engineer who came up with the name RenderMan. In 2015 Pixar started offering the noncommercial version of RenderMan for free. (The paid version is about $500.) The number of people using the free software is in "seven figures," says Ford.

It's been more than 40 years since Catmull made one of the world's first computer-rendered films, starring his left hand. Before I leave his office, he shows me the mold under a glass-domed cylinder casing, kind of like the rose from "Beauty and the Beast." Two of the fingers have broken off.

Time has been more forgiving to "Toy Story" than it has been to Catmull's plaster mold. He hopes Pixar will continue to age gracefully. "As you bring people into a successful company, you have different kinds of challenges," he says, then pauses.

"They can't make the first computer-animated film over again. How do they do the first of something? And how do they own that?"

This story appears in the winter 2015 edition of CNET Magazine. For other magazine stories, go here.