Though Santana were a major draw in their San Francisco hometown and had become favorites of influential impresario Bill Graham, they were virtual unknowns outside their city when they began playing the Woodstock Music & Art Fair at 2 p.m. on Saturday, August 16, 1969. By the end of their 45-minute set, they were on their way to being superstars. The energy and focus of their performance, so loose and funky and also precise, is still palpable, and Carlos Santana, the band’s leader and guitarist, appears to be inhabiting another plane (in a sense he was, due to an ill-timed dose of a hallucinogen). The band’s self-titled debut album, released a few weeks later, was an instant hit. Watch and listen to the film of them onstage at Woodstock : the flurry of percussion, all the metal and wood and rawhide and human hands, is where the ear goes first. Carlos, then 22, became enamored with Afro-Cuban music after he’d been playing for quite a while.…