Haynes understands that rock ‘n’ roll, and glam in particular, is powered by the promise of transformation: In “Velvet Goldmine,” everybody wants to be someone else — or at least shag them. A budding but as-yet-imageless young glam rocker becomes transfixed by an Iggy Pop-like god at an outdoor hippiefest: Shirtless, in sprayed-on leather pants, he sprinkles glitter like talcum powder over his scrawny, outlandishly sexy torso, urging his bewildered audience to taunt him. A teenage boy watching evening telly with his straight-laced, stony-faced parents sees a blatantly omnisexual glam star and virtually yells out, “That’s me, Da! That’s me!” In the whirling sphere of rock ‘n’ roll, a world of freedom is all within reach, with just the right clothes and a little bit of makeup. The simple explanation fed to us by too many people who’ve studied too much sociology is that rock ‘n’ roll is all about attitude. But “attitude” doesn’t begin to cover the subtle changes it works on us. And even if our concerned, worried elders think it’s going to be the end of us, really, it’s only the beginning.

That’s why, tempted as I am to tally all the faults of “Velvet Goldmine” (which was produced by Michael Stipe and Christine Vachon), I can’t write it off completely. Watching the opening credits — a stampede of kids running through the streets in flapping bell-bottoms, their velvet jackets flying open in the breeze, set to Brian Eno’s “Needle in the Camel’s Eye” — I felt as if I were falling in love, the way I always do at the beginning of “A Hard Day’s Night.” The euphoria wore off quickly. But for those few minutes, and during numerous other sequences scattered throughout the movie, I at least felt certain of Haynes’ commitment, vitality and heart. This isn’t one of those movies that treats rock ‘n’ roll as kid stuff.

“Velvet Goldmine” opens in London in 1974, with David Bowie-like superstar Brian Slade (played by Jonathan Rhys Meyers, with lots of pouty insouciance but not much else) faking his assassination (and ending his career in the process) during a performance, as Arthur Stuart (Christian Bale), a young fan, watches in horror from the audience. The story then flips forward 10 years, clearly using the structure of “Citizen Kane” as a template. In 1984, Arthur is a news reporter in the States who’s been assigned to find out what really happened to Slade. On the way to unlocking Slade’s secrets, he connects with Slade’s former manager (played by Michael Feast, whose embittered wistfulness is touching), and, more important, with the two people who figured most prominently in Slade’s early career: his former wife, Mandy (Toni Collette), and his former collaborator and lover, the volatile, seductive rocker Curt Wild (Ewan McGregor), who embodies Iggy Pop’s skin-and-bones sexuality. As Arthur investigates the story, he also relives his own love affair with the music and the people who played it, recalling how it catalyzed the slow, painful process of setting himself free from the expectations of his parents and the world at large.

Haynes’ story starts to fray fairly quickly — there are so many threads, laid out so haphazardly, that it’s sometimes hard to follow. His characterization could be sharper: He uses a few main models (Bowie, Pop, Lou Reed and T. Rex’s Marc Bolan) and attributes elements of each to three of the movie’s characters (Slade, Wild and a minor character named Jack Fairy), mixing and matching them so that no character is very sharply defined. And some of the music is defeated by the dreamlike set pieces meant to showcase it: They’re just too stagey to be effective.

But otherwise, the music in “Velvet Goldmine” is one of its main treasures. The soundtrack combines vintage Eno, Roxy Music and T Rex (reportedly, David Bowie wouldn’t grant the rights to his work), with some new songs written especially for the film performed by bands like Pulp and Shudder to Think. The older music, especially, is used beautifully: Just after Curt Wild and Brian Slade meet, we see them whirling around in little amusement-park cars, the world dark around them except for some candy-colored lights, set to Lou Reed’s plaintive, sweetly (and deceptively) deadpan “Satellite of Love.”

Haynes is best known for 1995′s “Safe,” but it’s a shame that his earlier movie, “Superstar: The Karen Carpenter Story” — a complex, dark and incredibly moving portrayal of the singer’s battle with anorexia that uses Barbie and Ken dolls instead of actors — is unavailable to the public. (Richard Carpenter squelched the movie after Haynes used the Carpenters’ music without first getting permission.) Although the two pictures are worlds apart in terms of scope and budget, “Velvet Goldmine” — sprawling, ambitious and sometimes just plain weird — represents the same kind of go-for-broke filmmaking. Haynes will try anything, and sometimes, amazingly, he pulls it off: In a nod to “Superstar,” he gives two glam-outfitted Ken dolls a brief, weirdly affecting love scene. He traces the roots of glam back to Oscar Wilde’s arrival on earth, in 1854, in a spaceship (and, of course, he shows it to us as a ring of hazy lights).

Haynes has a gift for shaping love stories: He never gives tenderness short shrift. There are times when he tugs a little too blatantly at our heartstrings, most notably when he’s telegraphing messages about homophobia. “Velvet Goldmine” contains the stock scene in which the uptight dad catches the young man masturbating and all hell breaks loose. Haynes tends to use such scenes as billboards, but they’d be much more potent if they weren’t quite so overplayed.

Haynes also saddles his actors with some pretty crappy dialogue (particularly some pat introspective folderol about how they set out to change the world and ended up changing only themselves). But for the most part, his actors seem completely in tune with him. Christian Bale — an underrated actor who brought charm and subtle shading to the role of Laurie in Gillian Armstrong’s “Little Women” — gets to the heart of both the eager innocence and the worldly hunger of his character; the way his face lights up when the performers he loves take the stage explains perfectly the way rock ‘n’ roll can make its fans feel elevated, transported. And Eddie Izzard is devilishly amusing as Slade’s Svengali manager.

But it’s Collette and McGregor, as the crucial elbows of the story’s love triangle, who really shine. McGregor’s Wild is a rock star who comes complete with a mythology of having grown up in a trailer park and undergone shock treatments as a kid (“to fry the fairy right out of him,” as one character puts it). McGregor nails Wild’s willfulness but also his vulnerability. In one sequence, with his bleached hair and skinny jerseys, Wild could pass for Kurt Cobain’s identical twin — perhaps as Haynes’ way of pointing to the future. Even when Wild is up to obnoxious rock-star antics, like pissing outdoors against an iron gate, there’s so much satyr-like delight in his smile and his laugh that it’s hard not to laugh along with him.

And Collette, as Mandy, the ambitious, forthright yet crisply fragile woman who becomes displaced by Wild in Slade’s affections, is heartbreaking. A sexually adventurous party girl in the early ’70s, by 1984 she’s hit hard times, coasting mostly on her name. When Arthur interviews her in a divey bar, she’s prickly at first, reluctant to answer his questions. She draws on her cigarette, using it as a shield, a defense mechanism. But the way she averts her eyes clues you in to how much Slade hurt and humiliated her, despite the fact that she’d bought wholeheartedly into the idea of sexual freedom. “It was a gorgeous, gorgeous time,” she tells Arthur. “We were all living our dreams.” Dressed in black clothes and somber-looking silver jewelry, she’s a far cry from the earlier creature we’d seen, a bird-of-paradise vision in ’70s leather and velvet and feathers. Of all the characters in “Velvet Goldmine,” she represents the deepest kind of mourning for the gorgeous time long past. She’s taken its loss the hardest — and the way Haynes has sketched it out for us, it’s easy to understand why its passing hurt so much.