“Very brilliant, a little erratic, embattled quite often. She suffered.”

Director Richard Linklater was describing his mom, Diane, who was a college professor, but he could easily be talking about the title character of “Where’d You Go, Bernadette,” his new comedy/drama that he dedicated to his mother’s memory.

“She passed away when I was in rehearsals, but I think she knew I was making it and my mom kind of permeates the movie. When I first read the book, I thought, for all of Bernadette’s wackiness, she does remind me a bit of my mom,” says Linklater, whose films include “Before Sunrise,” “School of Rock” and “Boyhood.”

“I never doubted my mom’s love and support for myself and my sisters but, yeah, she would occasionally run away from home. It sounds scary to some people, I guess, but that was just part of our lives.”

Bernadette (played by Cate Blanchett) also runs away in the film, presumably to give herself time to figure out her next step. With daughter Bee (Emma Nelson, in her film debut) about to leave for boarding school, should she return to the architecture career she abandoned? Meanwhile, Bee is positive her mom will return.

“While we were making the movie, some people were like, ‘Bernadette is getting rid of her phone and she’s not telling Bee where she is,’ but the bond is so deep that Bernadette knows she’s not abandoning her daughter,” says Linklater. “And you see Bee sticking up for Bernadette. She has a full-time supporter in her daughter, and that was how I felt about my mom. She was very strong, among her inconsistencies and problems.”

The five-time Oscar nominee’s mother isn’t the only family member reflected in the film. A scene in which Bernadette and Bee sing along to Cyndi Lauper’s 1984 hit “Time After Time” got him some nudges during an early screening of “Bernadette.”

“My daughters and I sing it in the car all the time, so that was sort of an Easter egg for them. When they saw the movie, sitting next to me, they both squealed,” says Link­later. (Older daughter Lorelai played Ethan Hawke’s daughter in “Boyhood.”)

The writer/director was introduced to Maria Semple’s novel by producer Megan Ellison, who raved about it to him and who liked his take on the material.

“In the movie, we do see the pathological/institutional path Bernadette could go down, but I was solidly in the camp that Bernadette is not crazy,” says Linklater, who co-wrote the screenplay with Holly Gent and Vince Palmo. “The world is crazy and it judges Bernadette too quickly. My take is that she just needs to get back to work creatively and do her thing and she’ll be fine. At a crucial moment, Bernadette was all-in for Bee — so all-in that she lost herself. So now it’s time for her to get her thing going.”

Linklater has been all-in for “Bernadette” for more than two years. Shot in the summer of 2017 and originally scheduled for release in early 2018, it took longer to get right than any of his 20 other movies.

“[Editor] Sandra Adair and I were in the editing room for much, much longer than usual,” says Linklater. “I don’t usually ‘find’ my movies in the edit room, but I would say this one, I did. We had to cut a lot of material. It ran long, I think because with an adaptation, you sometimes try to say too much, to make everything clear.”

The “Bernadette” shoot came in $1 million under budget so Linklater had some money to play with, but he says it was painful to cut scenes, including material that spotlighted a “wonderful character” played by Margaret Cho.

Reportedly, the director has moved on to a secret project that is related to the 1969 moon landing, although he did not mention it when asked what’s next for him. And movie lovers hoping for another of the “Before” movies (“Before Sunrise,” 1995; “Before Sunset,” 2004; “Before Midnight,” 2013) may not want to get their hopes up. He says he and actors/co-writers Hawke and Julie Delpy have not discussed it.

“It hasn’t quite been nine years [the gap between the previous films] but we usually had a plan by now. But nothing yet. I wouldn’t be surprised if it stays a trilogy and doesn’t expand to a quadrology — is that what you call it?

“That’s probably the reason we won’t do it,” says Linklater, with a hearty chuckle. “It’s too hard to pronounce.”