The show was a revolution, ending more than a decade of TV cartoon stagnation and inspiring the next generation of animators. But behind the scenes, the staff of Nickelodeon’s “The Ren & Stimpy Show” were feeling anything but “Happy Happy Joy Joy.”

A new documentary called “Happy Happy Joy Joy: The Ren & Stimpy Story,” which premiered at the 2020 Sundance Film Festival and hits streaming services Aug. 14, reveals the culture of anger and fear at the now-defunct Spumco studios, led by the show’s fiery genius and scandal-plagued creator John Kricfalusi.

“He had this sort of rockstar status,” an animator says of Kricfalusi in the fascinating, if occasionally long-winded doc. Adds another: “The whole thing is tragic. It really is like a Shakespearean play.”

Animation was in a sorry state in the late 1980 and ‘90s, and shows were being churned out that were cheaply made and more concerned with selling toys — “My Little Pony,” “Strawberry Shortcake” — than artistry. During this time, Kricfalusi, a true believer in the classic styles of Hanna-Barbera and Looney Tunes, was enthusiastically shopping around ideas to major studios.

In the memorable pitch sessions, Kricfalusi would do full character voices and exaggerated, highly physical gestures. “His glasses hit somebody in the head once,” a colleague recalls. But his non-conforming, subversive story ideas left execs feeling uncomfortable, and the animator says he was escorted out by a security guard at least once.

And then came Nickelodeon. In 1991, the kids network that had been reliant on foreign cartoons for more than a decade, wanted to branch out into original animated programming to be called Nicktoons.

Vanessa Coffey, a then-producer at Nickelodeon, wasn’t the usual TV exec. She was interested in weird, out-of-the-box notions, like those of Kricfalusi. He pitched her a show called “Your Gang,” but she was enamored by just two of his creations, Ren, an irate dog, and Stimpy, a stupid cat.

And thus “The Ren & Stimpy Show” was born.

Kricfalusi and his talented animator friends who had formed Spumco, Inc. in 1988 were tasked with delivering six episodes of the risky new program that consistently bordered on inappropriate. As dramatic as the documentary can be at times, it also admiringly delves into the off-the-charts creativity on display during that period. Bill Wray was painting museum-worthy backgrounds, and cartoon characters meant for kids were being modeled after Kirk Douglas (Ren) and Larry Fine from “The Three Stooges.” This was just not done.

When it premiered, “The Ren & Stimpy Show” became a major hit with critics and audiences alike. But despite the show’s boffo success — scoring a 4.0 (2.5 million viewers) in the ratings by episode 4 — Kricfalusi’s temper was on the rise.

The creator was known to furiously rip up his employees’ drawings, and to lock himself in his office for hours redoing already finished work.

“If they toned it down,” Kricfalusi says in the doc, “they’d get what people called ‘a beating.’”

One worker went further in the film, saying he was “a Hitler type.”

The man’s obsession with quality and pushing the envelope of censorship led to months-long delays and going hundreds of thousands of dollars over budget.

When he finally delivered the first episode of Season 2, a violent story called “Man’s Best Friend,” Coffey was appalled and rejected it. “He said that I ‘could go f–k myself’, he wouldn’t take notes anymore, that he made the network and that he was the star,” Coffey says in the doc.

Kricfalusi, who also was the voice of Ren, was fired after Season 2, and the show plummeted in many critics’ estimations. It was cancelled in 1995.

The creator never found the same success again, but in the ensuing years found himself in a #MeToo scandal. Director Ron Cicero’s film appropriately switches to a deeply serious tone.

In 2018, a Buzzfeed article revealed that in 1997 when Kricfalusi was 42, he started a sexual relationship with Robyn Byrd, a 16-year-old girl, and then later Katie Rice, another teen. Byrd says in the doc that she was a fan of “Ren & Stimpy,” and wrote a letter to Kricfalusi when she was just 14.

“I was falling in love with her letters,” Kricfalusi says in the doc. “She was too young. I freely admit that. But she was so convincing.”

Byrd interned with Kricfalusi, moved in with him and began a sexual relationship.

“I was isolated from everyone I know,” she says in the film, adding that her “entire adolescence from 14 to 21” was controlled by Kricfalusi.

Coffey says that when she read the article, she was deeply disturbed.

“It hurt that he used ‘Ren & Stimpy’ that way,” she says through tears in the doc.

Kricfalusi claims he didn’t realize the emotional havoc he’d wrought. “[I] felt like the lowest creature on earth,” he says of reading the story.

Today, while Byrd says she does not want fans of “The Ren & Stimpy Show” to abandon a cherished childhood memory, hers are forever scarred.

“I still have nightmares about him,” she says.