Gus Van Sant’s “Paranoid Park” has received mostly respectful reviews (see Rotten Tomatoes for a rundown of major reviewing activity on the film) from the nation’s movie critics, though not “glowing” or “excited” reviews. Most of them seem to get what Van Sant is up to — which is to give an atmospheric account of a horrific moment and its reverberations in an alienated teenager’s life. (The Oregonian’s Shawn Levy was among the most positive.) It’s a little too “arty” for some of them, with its fractured narrative line, scene repetitions and slow-motion, soft-focus sequences. But really, that’s what the film is about — to create an artistic affect, simple on the face of it but maybe profound and complex upon reflection. We’ll see.

“Paranoid Park,” which closely tracks the plot of Portland native Blake Nelson’s Young Adult novel (which I haven’t read), is a portrait of Alex (Gabe Nevins), a 16 or maybe 17-year-old kid in a small family that is breaking up. Van Sant doesn’t give us much background on Alex — he doesn’t have a psychological theory to explain him, no “causes” for his behavior, he doesn’t supply a case history. That’s OK, from a “coherence” point of view: Alex doesn’t have the equipment to analyze himself very thoroughly; and no one around him is interested enough to hazard a guess about what’s going on behind that placid (maybe slightly worried-looking) exterior. Except maybe for Macy (Lauren McKinney), his younger friend from down the street. More about her in a moment.

So, we don’t know exactly why Alex has started to get into skateboarding, what he was into before, what his status at school might be. We have to accept that he simply is into skateboarding, even though he’s not good at it yet. His friend Jared skateboards, too, and persuades him to visit Paranoid Park (the skater-constructed skate park under the Burnside Bridge, in actuality), where the best and scruffiest skaters hang out. Alex protests that he’s not ready for Paranoid Park, and Jared, in his one good line of the movie, replies: “No one’s ever ready for Paranoid Park.”

Spoiler alert! Ominous. “Paranoid Park” telegraphs all of its punches this way, though. Sure enough, Alex goes to the park by himself one night, meets up with some street kids, jumps a passing freight train with one of them to get some beer (unaccountably from a geographic point of view — beer shops along the tracks?), a security guard spots them and gives chase, starts swinging away at Alex with, what, his flashlight. Alex fends him off with his skateboard, knocking the guard off balance. He stumbles into the path of another train and is sliced in half — graphically.

The film then deals with Alex dealing with this event. He runs away; chants his defense (which is self-defense) to himself; covers his tracks; suffers; suffers alone. Because that’s the point. His “girlfriend” is a sexually rapacious cheerleader (someone has a strange fantasy going on here) and he drops her after their first sexual encounter. He doesn’t trust Jared with the story. He starts to tell his father (by phone) but doesn’t. His mother is the most fleeting of presences in the film. Teachers? No. The detective investigating the case? Of course not.

Alex is alone. When we see him, he is often writing alone (the account of what happened to him), on a bench at the Oregon coast, often. Or watching the skaters at the park alone. Or exchanging a few words with the cheerleader or other schoolmates. His face is impassive, dreamy, in soft focus, a face in transition like the personality behind it, vague, a stem cell that could become almost anything. The handheld camera skate sequences, shot in Super 8, have the same fuzziness, the same dreamlike quality. They aren’t spectacular — no Big Air tricks, no impossible maneuvers from one surface to another, not even any bone-crunching crashes — but again, that’s the point. The film seeks stillness, not activity. It presents — Alex. At this moment. No explanations. No excuses. In pain but not seeking sympathy.

Macy. Macy has feelings for Alex (watch her nervously work the hem of her skirt as she rides the bus alongside him) . She chats him up, even when he offers nothing. She’s smart and insightful (and McKinney has some gifts as an actor, too) and picks up that something has happened to him. She suggests that he write about what happened to him, and even gives him some sage writing advice: Write it as though you are writing for a friend. “Write it for me,” she says. And when he’s done with it? It doesn’t matter she says. The essential activity is the writing. He can burn it when he’s done.

What happens? Alex writes. He burns. Maybe he even copes. Will the authorities solve the death of the security guard? Will the image haunt Alex the rest of his life? Will Alex finally realize that Macy is the girl for him? Van Sant doesn’t care. He’s much more interested in that dreamy face, the way the curls frame it, the occasional flashes of anguish that crease it or send his hands to cover it, the pliability of the mind and the personality, its ambiguity, its vagueness. Like his Columbine massacre movie, “Elephant,” “Paranoid Park” is more about what we don’t know, what we can’t know, what we can’t express, than a description of what is. And so it isn’t activated by an outside agenda — Van Sant doesn’t explain Alex, let alone advise or reform him. He leaves Alex to his own (and Macy’s) devices. Our speculations about Alex’s life over and after the course of the movie? I suspect Van Sant would consider them useless efforts to understand something that is at heart opaque.

What is Van Sant inventing here? Maybe just a blank screen on which we project our own desires (to relive those teen days, perhaps, to understand the Other, to shelter, even to love and be loved), but a screen that distorts our desires enough to make the projection conscious: You are projecting; this is how and what you project. That’s a deft little trick, and maybe the best case I can possibly make for “Paranoid Park,” which can also be incredibly annoying at times (the depiction of the cheerleader, for example, is a grotesque, mean-spirited caricature, the untrained actors can be awful at times). The extreme simplicity of the plot and the characters is balanced by the complexity of the filmmaking as it strives to create that Effect (the inventive Christopher Doyle and Rain Kathy Li cinematography with its bow to Fellini, Leslie Shatz’s sound design with more Fellini shout-outs and Elliott Smith songs, etc.).

It’s an indication of Van Sant’s artfulness that he can pull this off at all. And at least on that basis, he continues to coax me back into the theater to see more movies.