The glamour. The period detail. The poor taste.

“Boogie Nights,” which hit theaters 20 years ago this month, looked back on the late 1970s and early ’80s San Fernando Valley from when it was shot in the mid-1990s. The area was already in transition at the time, and still is.

That’s partially why one of the movie’s key locations, sex film auteur Jack Horner’s cool pool party house, wasn’t even in the Valley. The vintage 1950s interiors director Paul Thomas Anderson was looking for had been upgraded by most homeowners north of the Santa Monica Mountains, but a perfect place that hadn’t changed was found in West Covina. That 1958, nearly 4,000 square foot structure was sold, by the way, two months ago for $1.21 million, with many of its original features reportedly still intact.

The film’s other unforgettable abode, Rahad Jackson’s pad where a coke scam went speedfreak-“Jessie’s Girl” bad, no longer exists in the Encino Hills. Anderson only used the actual exterior anyway. To better control the ratcheting chaos, the interior was built on a Hollywood soundstage.

The vulgarly decorated dream house Dirk Diggler bought himself with porn star money may have been mercifully remodeled in Woodland Hills, but will the venerable Studio City coffee shop Du-par’s – where Jack, Amber and Rollergirl seduced Eddie-soon-to-be-Dirk into joining their artistic endeavor – ever change?

Some more memorable “Boogie Nights” locations that evoke the ever-evolving, yet somehow always feeling like home, Valley include:

Montclair College Preparatory School: Not in the movie, but crucially where smut-obsessed, 17-year-old student Anderson cooked up the mockumentary short “The Dirk Diggler Story,” his first film starring acquaintance Michael Stein as the porn prince character who Mark Wahlberg would boogie to stardom nine years later. Fun fact: The little-known Stein also appears in the latest cinematic ode to L.A. strivers, “La La Land” (which we also found its local locations).

Reseda Theater: The neighborhood movie palace had been closed for years when the film crew slapped the bright “Boogie Nights” sign across its marquee to set off the picture’s audacious opening shot. The Reseda’s still there and as shut down as ever, its marquee vulnerably naked.

Hot Traxx Disco: That opening crane shot continued down Sherman Way and across Canby Ave. to what had been the landmark Reseda Country Club ’80s concert venue. The shot continued by Steadicam into the pulsating nightclub, introducing us to many of the main characters and their happy, hedonistic ways. Anderson wanted to top the Copa shot from Martin Scorsese’s “Goodfellas,” and what he, cinematographer Robert Elswit and all involved pulled off was truly miraculous. The building now houses the Restauracion Spanish language church.

Sound City: The Anderson-beloved “Jessie’s Girl” and (sob) Tom Petty’s “Damn the Torpedoes” were just two of hundreds of rock classics recorded at this legendary Van Nuys facility (the subject of its own fine documentary). It’s also where Dirk tried to prove he had more than one talent – and the former pop rapper Marky Mark proved he could really act by singing dreadfully. The landmark studio shut down or sub-leased its rooms in the 21st Century, but re-opened recently with equipment upgrades as well as vintage recording tools.

Miss Donuts: The strip mall bake shop where Buck Swope found himself in a bloody crossfire while on a late-night cruller run is still the same on Sherman Way, albeit now advertising menu additions like empanadas.

“It’s very old, everything,” owner Albert Tran, who bought the place in 2000, chuckles. “We need to remodel.”

A customer once tried to show Tran the shocking “Boogie Nights” sequence on a cell phone, but he was too busy in the always bustling store to really watch much. The gory tableau hasn’t scared away patrons, apparently; indeed, rather the opposite.

“Quite a few people come in because it’s in ‘Boogie Nights’,” Tran beams. “We’ve become very well-known because of the movie. Some people even call it the Boogie Nights Donut Shop, they don’t call it Miss Donut.”

Several shows have shot at the location since Anderson’s crew did, including an early episode of the Valley-set cable series “Ray Donovan.”

“They don’t mention why they shoot here, but they just like this place,” Tran shrugs. “I don’t know why; it’s an old donut shop!”

Don’t ever remodel, Albert.