Oculus CTO and programming luminary John Carmack has published a statement refuting some of the allegations levelled at him and his employer during the recent Zenimax vs. Oculus trial -- a trial which virtual reality company Oculus lost.

Carmack rarely offers such lengthy commentary in public, but after coming out on the losing end of a $500 million court case that revolved around him, he was compelled to go public with his side of the story.

"The Zenimax vs. Oculus trial is over. I disagreed with their characterization, misdirection, and selective omissions," he wrote. "I never tried to hide or wipe any evidence, and all of my data is accounted for, contrary to some stories being spread."

Carmack used to work for Zenimax subsidiary Id Software (which he founded) before leaving the company to work at Oculus, which Facebook bought for $2 billion in 2014. Carmack joined Oculus in 2013.

Last summer, Zenimax accused Carmack of copying thousands of documents from a Zenimax computer to a USB storage device. Zenimax said those files were crucial in Oculus' effort to get its VR business off the ground.

In his post-trial statement, Carmack took issue with those accusations of code theft, saying Zenimax's courtroom expert made claims that were plain wrong. "The plaintiff’s expert that said Oculus’s implementations of the techniques at issue were 'non-literally copied' from the source code I wrote while at Id Software," he wrote. 

"This is just not true. The authors at Oculus never had access to the Id C++ VR code, only a tiny bit of plaintext shader code from the demo. I was genuinely interested in hearing how the paid expert would spin a web of code DNA between completely unrelated codebases."

For context, non-literal copying refers to a type of infringement where a program's primary functions are reproduced using different code. 

The analogy Oculus' expert gave to the jury posited if someone wrote a book that was for all intents and purposes Harry Potter, with a few name changes, it would still be copyright infringement. 

Carmack himself agreed with that point, but went on the explain that if you "abstract Harry Potter up a notch or two, you get Cambell's Hero's Journey, which also maps well onto Star Wars and hundreds of other stories. These are not copyright infringement."

"There are objective measures of code similarity that can be quoted, like the edit distance between abstract syntax trees," he said. 

Carmack took issue with Zenimax's expert's presentation, accusing the plaintiff of misleading the court with illegible slides.

"It was ridiculous," he wrote. "Even without being able to read the code on the slides, you could tell the steps varied widely in operation count, were often split up and in different order, and just looked different."

Further questioning the credibility of Oculus' expert, Carmack noted that he himself wasn't allowed to read the full expert report, and said that if the code examples were made public "the internet would have viciously mocked the analysis."

Carmack also strongly suggested that the expert witness, apparently an academic, sold their integrity for a high-paying gig.

"The expert witness circuit is surely tempting for many academics, since a distinguished expert can get paid $600+ an hour to prepare a weighty report that supports a lawyer’s case," he said. 

Zenimax initially pushed for the Jury to award the company $2 billion in compensation plus another $2 billion in punitive damages. 

In the end Zenimax was awarded $500 million after a jury ruled that Oculus didn't illegitimately obtain trade secrets, but that Oculus co-founder Palmer Luckey did indeed violate a non-disclosure agreement.

You can read the Carmack's complete statement over on Facebook.

UPDATE: Zenimax has responded to Carmack's criticisms, and has offered the following statement to Gamasutra:

"In addition to expert testimony finding both literal and non-literal copying, Oculus programmers themselves admitted using Zenimax’s copyrighted code (one saying he cut and pasted it into the Oculus SDK), and [Oculus VR co-founder] Brendan Iribe, in writing, requested a license for the 'source code shared by Carmack' they needed for the Oculus Rift. Not surprisingly, the jury found Zenimax code copyrights were infringed. The Oculus Rift was built on a foundation of Zenimax technology."
 
"As for the denial of wiping, the Court’s independent expert found 92 percent of Carmack’s hard drive was wiped—all data was permanently destroyed, right after Carmack got notice of the lawsuit, and that his affidavit denying the wiping was false. Those are the hard facts."