NEW YORK -- Half-moon hoops, double rims, chain-linked fences for out-of-bounds lines and no net that anyone can recall.Such is the imperfect urban landscape of playground basketball, what many consider the truest expression of the sport. It's basketball without referees, coaches or sneaker deals. Anyone can play, so long as they call "Next."A new documentary, "Doin' it in the Park," is a loving ode to the blacktop world of New York City pickup. With more than 700 courts, it's the mecca of pick-up basketball, featuring places like Rucker Park in Harlem and the West 4th St. court, a kind of fish bowl of nonstop basketball on view for West Village commuters and tourists. Basketball is woven into the asphalt fabric of New York.