In 2010, Palmer Luckey designed the first prototype of the Oculus Rift. This prototype, built on a shell of another virtual reality headset, was only capable of rotational tracking. However, it boasted a 90-degree field of vision that was previously unseen in the consumer market at the time. Distortion issues arising from the lens used to create the field of vision were corrected for by software written by John Carmack for a version of Doom 3. This initial design would later serve as a basis from which the later designs came. In 2012, the Rift is presented for the first time at the E3 video game trade show by Carmack. In 2014, Facebook purchased Oculus VR for what at the time was stated as $2 billion but later revealed that the more accurate figure was $3 billion. This purchase occurred after the first development kits ordered through Oculus' 2012 Kickstarter had shipped in 2013 but before the shipping of their second development kits in 2014. ZeniMax, Carmack's former employer, sued Oculus and Facebook for taking company secrets to Facebook; the verdict was in favour of ZeniMax, settled out of court later.