Prince is clearly among the most influential and talented pop figures of the last several years, but his latest feature vehicle, Graffiti Bridge, written and directed by the diminutive auteur himself, proves only that as a filmmaker, he's a great musician. A loose sequel to the far superior Purple Rain, it's set in a sort of arrested male adolescent fantasyland; all the people in the picture are young, fashionably dressed, and able to spend all their time listening to live music at MTV-style nightclubs where guys don't drink or take drugs or do much of anything except treat their girlfriends like hookers. There's a flimsy plot about a rivalry between the star and the still-amusing Morris Day (of the funk band the Time), and an incomprehensible subplot about a woman who is either an angel or a groupie. But none of it makes any sense whatsoever, and Prince's direction (forget his performance one long ''I'm a sensitive guy in pain'' pout) is devoid of energy, even in the musical numbers that are (theoretically) the reason you're watching this. In fact, the staging is so lethargic you'll be hard-pressed to remember how good these songs sounded on CD.