Is it true that your little son Racer came up the idea for Shark Boy And Lava Girl?

Yeah, he’s my Frank Miller on this one, I guess. He comes up with ideas that only an 8-year-old boy could come up with. At first, I was just going to draw it as a storybook. Then the studio rang and said they wanted to do another movie in 3D. And I didn’t have any ideas so I just said, “Er, Shark Boy and Lava Girl… in 3D?” And they said it sounded great. I told the studio it was my son’s idea and they’re like, “We’re signing him up!”

It’s an incredibly imaginative movie...

You can go anywhere you’re your mind. Some people need a drug to free up their minds, but I’ve never had that problem. Ever since I was a kid, I’ve just dreamed up the wildest things. My kids are same – their minds just jump there. I’ve never done drugs and I’m not really a drinker, which people find very strange because my movies are so out there. Imagine if I did!

So you weren’t worried that your kid’s ideas were too wacky?

There’s a fearlessness that children have, that you have to try to keep. Because as you get older, you start fearing too much – and that’s why drink or drugs will free you up to let the fear go. But fear is part of the creative process. Am I good enough? Can I do it again? That’s all part of creating. No matter how good you get, you should always be afraid. It drives you to better.

What’s your feeling on 3-D? Is it more than a gimmick?

Depends how you use it. I mean, Jim Cameron’s using to recreate depth and reality, and I’m using it more for gags because I know that’s my audience for this. I just saw a clip of /Singin’ In The Rain/ that they did in 3-D and it looks amazing. It’s not flying out of the screen at you, but it just makes you feel like you’re there. There’s so much more depth, it feels so much more real than just looking at a flat screen.

Still happy doing films for Harvey and Bob at Miramax?

There’s no other company like it. I can say, “I’m making this movie on Wednesday, send me the money!” And they’re like, “Alright!” These guys own their own company so the buck stops with them – it’s like working for the original Warner brothers. They’re the top guys – there’s no one underneath them, no one above them. They always have great ideas and they’re bold enough to tell you if they think something doesn’t work. But then, I always have final cut! They love the movies as much as me.

Your next Miramax gig is a buddy-up with Tarantino, right?

We’ve already started working it; I shoot in the autumn. It’s a double-feature horror-thriller where he directs one and I direct one. They’re kind of truncated features of about 60 minutes - it’s like a night at the movies, where you go and see two movies at once. And we’ll have fake trailers done by filmmakers for movies that don’t exist. It’ll be cool...