When denim label G-Star Raw opened its biggest flagship store in Shanghai, fashionistas flocked to see the label's head designer Pierre Morisset.

The legendary Frenchman is regarded as the Steve Jobs of the denim world.

"I think the success of denim, first, is its beauty. Second, you don't need to wash it. It's just like the raincoat," he says, in the store's lounge in December, wearing all-blue denim from top to toe.

Morisset fell in love with denim at the tender age of 10. His father got a pair of jeans from an American soldier after the war, and hung them up in the garage.

Attracted by their color and style, the young Morisset used to sneak into the garage and eventually tailored the jeans to fit him.

In the 1990s, he joined G-Star Raw. Morisset spent a lot of time thinking about the identity and the image of the product. According to him, it is this that separates G-Star Raw from the competition.

"Every (denim) company was making the same pants, copying old American brands like Lee and Levi's Jos van Tilburg, founder of G-Star Raw, said to me: Pierre, think about it, what will denim be like within 20 or 30 years."

The answer came to him one day when he saw a guy driving a motorcycle down a small street in southern France. It was raining and when the guy got off the motorbike and walked toward Morisset, he saw that his denim jeans were stuck to his calves because of the rain and mud.

Jeans at that time were designed on a flat surface, but when wet they appeared to be like cylinders and it suddenly occurred to Morisset that denim pants should be created three-dimensionally.

Inspired, he created G-Star Elwood in 1997, the first three-dimensional jeans in the world. Because of the special cutting skill, buyers felt like they were "stretching" the denim when they wore it.

Now it is the second most popular cut of jeans in the world, with more than 13 million pants sold to date.

G-Star Raw started in the Netherlands, in Europe rather than the US, and Morisset believes this gave the jeans an independent blueprint.

"We are making denim inspired by function. Fit is what we are working on, and this is my identity. We don't follow nor make fashion. We just make what we like," Morisset says.