When the shooting started, it was much easier than he had expected.
The first sex scene between Qin's character and his boyfriend went smoothly, as Qin was acting opposite an amateur actor Wu Wei, a fresh college graduate.
"His reactions were so natural it was a smart choice on Lou's part," he says.
There were some really difficult scenes, though, but Lou knew how to motivate his lead actor.
"He told me that many people would thank us for shooting this film," Qin says. "When I realized that what I was doing was more than just a film, I felt like I was on some noble mission."
Although some of his friends are gay, Qin says he knew little about their world. To prepare for the film, Lou took the actors to gay bars and asked them to read books and watch films, such as Pedro Almodovar's Bad Education.
"This is a group that is still under great social pressure in China," says Qin. "I hope those who watch our film will see them in a different light."
Qin was also enthused by Lou's trust in his actors.
In one scene Qin was supposed to "put down the book and look outside the window", as per the script. But after Qin had looked outside for 20 minutes Lou was still silent. Qin had to look back at his boyfriend lying on the bed and interact with him for another 20 minutes, all impromptu. The cinematographer's hands began shaking, as the entire film was shot by hand-held cameras.
When Lou said the final "cut!" both Qin and the cinematographer shouted: "What the hell is going on?"
Lou said: "I think your non-scripted performance was good so I just let you go on."
The film, which Qin says will screen in France and Taiwan this September, is his fifth since graduating from the Central Academy of Drama in 2000 and the first in which he has had the lead role.