For more than two decades, the critical community of American film has been inclined to dismiss John Landis as somehow unworthy of appreciation by the mere fact that he has sold so many tickets. The director of such 1980s comedy classics as “Animal House,” “An American Werewolf in London,” “Trading Places,” and “The Blues Brothers” (not to mention Michael Jackson’s groundbreaking video for “Thriller”) has never been nominated for an Oscar, though he has earned three Razzie nods. But lately it seems as though the incoming generation of critics and film programmers, which grew up on Mr. Landis’s canonical 1980s work, is restoring the reputation of this underappreciated and, lately, under-seen craftsman.

Meanwhile, Mr. Landis has never stopped energetically and expertly plying his trade, and on Saturday, “Mr. Warmth: The Don Rickles Project,” the most recent fruit of his filmmaking labors, will make its premiere at the New York Film Festival. An affectionate and very funny biographical documentary portrait of the comedian and actor Don Rickles, “Mr. Warmth” is Mr. Landis’s fifth foray into nonfiction filmmaking. “Documentaries are very interesting,” the director said this week. “It’s a very strange experience for me as a narrative filmmaker.” Mr. Landis attributed part of that strangeness to a loss of directorial control. “When you’re directing a regular movie,” he said, “everyone’s energy is basically to give the director the moment he wants in front of the camera right there. If you are doing it at all rationally, you have a screenplay and then you shoot that screenplay and then that’s your film.”

The live footage in”Mr. Warmth” of Mr. Rickles doing his stage show to a packed audience at the Stardust Hotel in Las Vegas is the essence of unscripted. For the many who know the 81-year-old funnyman primarily from his television and movie appearances, his act will be a revelation.

“He’s not a comic,” Mr. Landis, said. “People always call him a stand-up, but the truth is that he’s a performance artist.” Alternating blistering salvos of improvised audience baiting (“go home and die!” he growls at one elderly fan) with blissfully corny snatches of song and dance, Mr. Rickles expertly manipulates his audience with a hypnotic combination of unction and sentiment so aggressively entertaining that the illusionist Penn Gillette likens it to Iggy Pop’s performances. “I’ve seen Don perform a hundred times,” Mr. Landis said. “But there’s always something that throws you off, something that comes from nowhere that just is so funny.”

Mr. Landis has known Mr. Rickels since they met on the Yugoslavian set of “Kelly’s Heroes” in 1968. Mr. Rickles had been cast in the film as Staff Sergeant Crapgame, one of a group of American GI’s looking to requisition a cache of Nazi gold. And though Mr. Landis made a brief unaccredited appearance as a nun, he was hired for a different job. “I don’t know if you know this, but production assistant is a relatively new term,” he said. “They used to be called gofers. I was a gofer.”

In the decades that followed, the two men became close friends.

“Mr. Warmth” documents both Mr. Rickles’s rise from modest beginnings in Queens, and Las Vegas’s fall from its glamorous mafia-run 1950s heyday. And though it took little convincing to get Mr. Rickles’s friends, family, and fans — including Billy Crystal, Robert DeNiro, and Chris Rock — and family to participate in interview segments, the man of the hour was initially reluctant to submit his stage show to camera scrutiny.

“It took a long time for him to agree to let me shoot his act,” the director said. For performers of Mr. Rickles’s generation, immortalizing their club routines for posterity was considered career suicide. “George Burns told me that TV is the great destroyer,” Mr. Landis said. An audience’s short memory and a veteran performer’s longevity guaranteed substantial leeway in retaining time-tested gags. With television, the anxiety for touring comedians was that “you’re on one night and then they know your act,” Mr. Landis said. “Don didn’t want me to film his act because he’s been doing it for 50 years.”

But when Mr. Rickles viewed an assembly of the film’s performance segments, his reaction was positive, albeit somewhat surprisingly and specifically focused. “He was watching and watching,” Mr. Landis said. “Finally I said, ‘What is so fascinating? You’ve done this for years.’ He said, ‘I’ve never seen me from behind!'”

Years of small-screen work on Dean Martin celebrity roasts and the Tonight Show had accustomed Mr. Rickles to a narrower view than Mr. Landis’s dynamic visualization of the actor prowling the stage and wading into the audience. “A cabaret and TV comic, he’s only shot proscenium,” Mr. Landis said. “Any other angles to him were a revelation.”