That autobiography, ''Before Night Falls,'' was published in English in 1993 and named one of the best books of the year by The New York Times Book Review. Now it has been made into a feature film by Julian Schnabel, the painter who made his filmmaking debut in 1996 with ''Basquiat.'' The book is a literary scrapbook of long and short takes, moving back and forth in time as memories boil up to the surface and disperse. The film capitalizes on this structure. Mr. Schnabel created the screenplay in collaboration with Cunningham O'Keefe, a friend of his, and Lazaro Gomez Carriles, the heir to Arenas's estate. They drew on scenes from not only the memoir but also the novels ''Hallucinations'' and ''The Color of Summer'' as well as a long prose poem called ''The Parade Ends.'' In addition, the director freely alternates scenes of meticulously detailed realism with flights of fantasy.

This collage includes dabs of invented incident as well as archival footage of the Cuban revolution and the 1980 Mariel Harbor boatlift, which carried Arenas and over 120,000 Cubans to bittersweet freedom in Miami. Both the book and the film unpredictably intermingle idyllic and erotic imagery with irreverent humor and tales of torture all the more horrifying for being a little-documented piece of recent history. When ''Before Night Falls'' opened at the New York Film Festival last month, the Times critic Stephen Holden wrote, ''Like a deathbed dream it leapfrogs through Arenas's life, reconstructing crucial moments as a succession of bright, feverish illuminations. . . . It dips into his imagination, plumbing the sources of his art in scenes that evoke his closeness with nature and his obsession with sex.''

The centerpiece of the movie, which opens commercially on Dec. 22, is the leading performance by Javier Bardem, the handsome star of such Spanish films as ''Jamon, Jamon,'' ''Mouth to Mouth,'' and Pedro Almodovar's ''Live Flesh.'' For his remarkable embodiment of Reinaldo Arenas, Mr. Bardem won the best actor prize at the Venice Film Festival last summer, where the film was runner-up for the grand jury prize.

What inspired Julian Schnabel, a twice-married painter with a New York Jewish background, to make a film about a gay poet who escaped from Castro's Cuba and committed suicide rather than die of AIDS? That was the question on my mind when I arrived at the imposing building Mr. Schnabel owns in the West Village.

He met me at the door, friendly and garrulous, wearing a sleeveless denim vest with a sarong tied around his ample waist, his hair and goatee long and unkempt. As we made our way from the second-floor living space to his third-floor studio, we walked through gargantuan rooms filled with gargantuan paintings. One room was furnished like a Victorian sitting room, another suggested a dim gallery at the Met's Michael Rockefeller Wing, and the kitchen looked like something from an Italian farmhouse, with a long rough wooden table still laden with breakfast dishes.

The cavernous skylit studio somehow seemed practically empty, despite the presence of a grand piano, a large round work table, some armchairs and numerous massive paintings in various stages of completion. There seemed to be a whole other network of rooms beyond the studio, because people kept appearing from behind closed doors -- an elderly Spanish-speaking gentleman taking Mr. Schnabel's pit bull, Zeus, out for a walk, for instance, and the painter's wife, Olatz Lopez Garmendia (a Spanish-born model who plays Arenas's mother in the movie). It was the afternoon before the second screening at the New York Film Festival, and the phone lines were busy with last-minute logistics. The environment impressed me as being both self-consciously ''legendary'' and enviably cool.

Mr. Schnabel said he'd first heard about Arenas through a Cuban real estate agent in Miami named Esther Percal. ''She told me I had to see this documentary that Jana Bokova made called 'Havana,' '' Mr. Schnabel said. ''So for $25 we bought a black-market copy of it in a bodega in Little Havana. It's an oral history of Cuba, interviews mixed together with fragments of these people's writings, including Virgilio Pinera and Guillermo Cabrera Infante. Reinaldo comes on and starts talking, and the guy is so funny and so modest. I was so impressed with him that I read 'Before Night Falls.' ''

He had just finished making ''Basquiat,'' a smart, stylish and insightful portrait of Jean-Michel Basquiat, the prodigiously talented painter who, like Mr. Schnabel, emerged as a blazing star of the New York art world in the 1980's but who flamed out in a drug overdose at the age of 27. ''After I made 'Basquiat,' a movie shot in New York that was very vertical, I wanted to make a movie like 'The Seven Samurai' or 'Andrei Rublev,' '' Mr. Schnabel said. ''I wanted to shoot outdoors. I wanted a huge depth of field.''

Arenas's book offered up just such depth, with its plethora of poetic images: the dirt-poor countryside, the gleaming fields of sugar cane harvested with revolutionary fervor, the island as penitentiary, the tropical boy's first glimpse of snow, the ghostly existence of an exile in New York. There would turn out to be significant similarities between Mr. Schnabel's two movies. Both champion highly original artists who achieved some measure of fame without being assimilated into the mainstream. ''I'm interested in the distance between people and society, the distance between how one person sees something and the way everybody else sees it,'' he said. ''That's something you can do with a film.''

Among the many pleasures of ''Basquiat'' were Mr. Schnabel's savvy way with a soundtrack, his sly use of celebrities (David Bowie played Andy Warhol, and the director himself was represented by a character played by Gary Oldman), and his interpolation of nonlinear elements to suggest an artist's inner consciousness. The same surprising mixture informs ''Before Night Falls,'' in which Sean Penn and Johnny Depp make flashy cameo appearances.

''I feel like with most movies, I always know what people are going to say, what the next scene is going to be,'' Mr. Schnabel said. ''Maybe it's because I'm always thinking about five different things at once, but I believe reality is layered the way this movie is. You don't have to communicate in a way that's so didactic, pedantic, where your food is chewed for you. I give the audience more credit and let them take the ride for themselves.''

Without being preachy, Mr. Schnabel took seriously the responsibility of representing Arenas's story. ''By the nature of his mere existence, Reinaldo becomes a political figure,'' he said. ''By the nature of me deciding to tell his story, it becomes a political movie. I don't know a damn thing about politics. I'm not on the right or the left, and I don't want to be used under any opportunistic labels.

What I think is really good is that I'm not homosexual, and I'm not Cuban. You can never be totally objective about anything, but people can't say, 'Oh, this guy's got an ax to grind.' I'm somebody who's verifying that these things happened. It's a moment in history. Castro does control the newspaper and the television in Cuba. Many people who lived there don't believe there are forced-labor camps.''

Those familiar with Arenas and his experience of contemporary Cuba agree that Mr. Schnabel succeeded in packing an enormous amount of the story into a two-hour film. ''It's impressive to see how deeply and profoundly a foreigner like Schnabel understood Reinaldo's agony,'' the Cuban documentary filmmaker Orlando Leal said in a telephone interview. ''He saw it as a human tragedy beyond any partisan point of view, without any political agenda,'' Mr. Leal said.

In addition to ''PM,'' an excerpt of which runs behind the closing credits of ''Before Night Falls,'' Mr. Leal's films include ''Improper Conduct,'' in which he and the late cinematographer Nestor Almendros interviewed Cuban homosexuals, including Arenas, about their treatment under Castro.

''I knew Reinaldo very well,'' Mr. Leal said, ''and I was impressed with the way Javier Bardem captured his speech pattern, his body language, his essence. It would have been easy to create a caricature of a brilliant, humorous homosexual, but he served the many facets of Reinaldo's personality.''

Needless to say, as in any biographical portrait, there are a few aspects of Arenas's life that don't make it to the film. In this case, readers of ''Before Night Falls'' will recall that virtually every other page of the memoir details some kind of sexual encounter with animals, trees, uncles, cousins, soldiers, fellow bus passengers, etc.It's no criticism of Mr. Schnabel's film to point out this omission.

According to the director, the first screenplay he commissioned was so faithful to Arenas's capacious sexual appetite that not even Pasolini could have filmed it. Similarly, the film depicts Arenas's illness within the established conventions of Hollywood's treatment of AIDS -- a halting walk and a few tasteful spots on the pallid face of a movie star.

Whereas in an essay memorializing Arenas in his book ''Eminent Maricones,'' Jaime Manrique recalls the last time the two men met: ''The door opened, and I almost gasped. Reinaldo's attractive features were hideously deformed: half his face looked swollen, purple, almost charred, as if it were about to fall off.''

Perhaps it was merciful Mr. Schnabel to spare moviegoers this sight. Nevertheless, the director delivers his own grotesque image of the Cuban writer's demise: he dies with a plastic shopping bag bearing the ''I NY'' logo over his face.

When I pressed him to recall what it was about the memoir that seized his filmmaker's imagination, he started by saying: ''I'd always been in love with Cuba. I was born in 1951. My parents took me to Florida as a kid. I was weaned on Cuban music. I was always in the yard listening to Trio Matamoros, Celia Cruz and Ignacio Pinera.'' He talked about his wife's Basque family heritage, and his admiration for Walt Whitman, and his trips to Cuba.

''It's a great country and it's very beautiful,'' he said. ''It's just a pity than an Italian tourist has more rights than a Cuban citizen.''

And he repeatedly recited from memory long passages of Arenas's writing -- sometimes in Spanish as well as English -- as if to establish his credentials.

Finally, he stopped and said: ''I really couldn't explain or give a logical or reasonable excuse why I should make this movie. I couldn't explain to Cabrera Infante or anyone I wanted to talk to what would qualify me to make this movie.

''Because I liked Cuban music when I was a baby? So what? What was the qualification? I still couldn't give you that answer.''