Without Brian Wilson, the world would be devoid of West Coast anthems like “California Girls,” “Good Vibrations” and “Surfin’ U.S.A.”

The musician and record producer, who founded the Beach Boys in 1961 with his brothers Dennis and Carl, as well as their cousin Mike Love and friend Al Jardine, is the subject of a new documentary, “Brian Wilson: Long Promised Road.”

Directed by Brent Wilson, who has no relation to the singer, the film is premiering at this year’s Tribeca Festival on June 15. “Long Promised Road” features guest appearances by Bruce Springsteen, Elton John and Nick Jonas and gives the Beach Boys icon an opportunity to reflect on his life and music.

In an exclusive clip of “Long Promised Road,” Wilson discusses his songwriting process with Rolling Stone’s editor Jason Fine, his longtime friend, on their way into the recording studio.

“[You] start with a background track, then you do the background vocals and then you do the leads,” he says.

That’s the secret sauce that helped Wilson draft nearly two dozen Top 40 hits, including “Surf City,” “I Get Around” and “Help Me, Rhonda.”

After a long hiatus, Wilson says “it’ll be nice to be back” in the studio with his fellow Beach Boys — Mike Love, Al Jardine and Bruce Johnston.

“I’m nervous,” he admits to Fine before getting out of the car. Fine reminds him, “It’s like you say when you go back on stage. You’re nervous for about two minutes.”

“Right,” Wilson acknowledges. “And then as soon as I hear ‘California Girls,’ I’m cool.”