If you haven't heard of "Twilight," ask a teenager. The best-selling young-adult book isn't bound for the big screen until December, but fan frenzy for the film practically took over Comic-Con on Thursday.

Hundreds of teens camped overnight outside the San Diego Convention Center for a chance to see early footage of the film and get a glimpse at the cast of heartthrobs set to bring the teen-vampire tale to life.

"You don't understand it until you've read it," said 17-year-old Syena Sarrafpour. "The cast of amazing people _ they're hot _ obviously adds to the excitement."

She and her friends wore homemade T-shirts touting their love for Edward, the vampire hero who falls in love with a human girl.

"It's a really good love story that has fantasy," said Emma Quan, 18. "It's like 'Harry Potter' plus romance plus good-looking people."

Thousands of fans _ many in homemade shirts proclaiming their preference for Edward or his love-rival, Jacob _ filled the convention's largest exhibition hall, drowning out the cast introductions with enthusiastic, high-pitched screams.

"Oh my God, Robert Pattinson is so hot," said 17-year-old Jenna Barazsu. "I love him. He's perfect for Edward."

Pattinson, 22, said he was overwhelmed by the attention the role has brought him.

"It's kind of terrifying in a lot of ways," he said in an interview. "I still can't really come to terms with it... As soon as one person started to recognize me, literally now I'm just freaking out the whole time."

The British actor previously appeared as the doomed Cedric Diggory in "Harry Potter and the Goblet of Fire" and "Harry Potter and the Order of the Phoenix."

But it wasn't just the boys who generated buzz. Fans were just as excited to see Kristen Stewart, who plays the story's heroine, Bella Swan. Continued...