Shia LaBeouf insists he's not "completely out of [his] mind" when it comes to committing to a movie role.

The actor is set to do authentic sex scenes in the Lars von Trier film Nymphomaniac. Shia admits he does have limits with role immersion though.

"There are rules," he told USA Today. "I have ethics, I'm not completely out of my mind.

"But I don't think there's anything wrong with sex. Sex is beautiful if it's done right. And I wouldn't just do it for no reason. Sex is different than love, and there is a separation, and that middle gap is what the movie's about."

Shia has turned his back on big Hollywood blockbusters in favour of independent movies. The 26-year-old star - who is famed for his role in the commercially successful Transformers franchise - doesn't care for big budgeted projects.

"All I'm really trying to say in the most politically sensible way is, 'Thank you so much for giving me the opportunities, I would just like to make movies about people now.' That's it," he explained.

"If I could give the money back and get all the credibility in the world that I'm seeking, I would do it tomorrow. In a heartbeat."