A U.S. jury in Texas on Wednesday ordered Facebook Inc., its virtual reality unit Oculus, and other defendants to pay a combined US$500 million to ZeniMax Media Inc., a video game publisher that says Oculus stole its technology.

The jury in federal court in Dallas found Oculus, which Facebook acquired for about US$2 billion in 2014, used ZeniMax’s computer code to launch the Rift virtual-reality headset. ZeniMax alleges that video game designer John Carmack developed core parts of the Rift’s technology while working at a ZeniMax subsidiary. Oculus hired Carmack in 2013.

Well-known for helping to conceive games such as "Quake" and "Doom," Carmack worked for id Software LLC before that company was acquired by ZeniMax. He is now the chief technology officer at Oculus.

Facebook chief executive Mark Zuckerberg testified last month during the three-week trial that none of ZeniMax’s proprietary code was incorporated into the Rift.

Oculus did not immediately respond to a request for comment.