Valve dev explains why Half-Life 2's eyes were (and maybe still are) the best in the biz

Half-Life 2 has aged gracefully since its debut almost 20 years ago. The classic shooter is still fun to play, its storytelling laid the groundwork for generations to come, but most of all, the game had unbeatable eyeballs.

Game developer Joe Wintergreen dug into how Half-Life 2’s eyes are the best in the biz in his Dev Scoops blog. “At one point I was trying to make my characters’ eyes nice, and the gold standard for that was (and arguably still is Half-Life 2,” Wintergreen wrote. He explains that the character’s eyes aren't “rotating meshes with bones, they’re more-or-less flat planes with shaders on ‘em that make ‘em look like balls.”

Once Birdwell and the team had the three main textures, it was all about getting the placement of the iris and cornea right to “make eye contact.” Birdwell says “the numbers for this can be found in any basic eye anatomy book.” Aspiring eye makers shouldn’t “worry about eye twist,” since our eyes “slightly spin when you look around due to how the muscles are attached, but it’s not human perceivable.” I did, in fact, spin my head after reading this information. And I can confirm that it is, annoyingly, very perceivable once you can’t stop thinking about it.

“I think an example for this code might still exist in the SDK, maybe in hlmv?” said Birdwell. “I know eventually it all got replaced with a fancy shader that does it all on one pass, but the HL2 era version didn’t and the code might all still be there.”

Digging through code is a Half-Life fan specialty at this point. The recent ports for Portal’s Switch release were hiding Half-Life 2 code, for some reason, and a modder naturally found a way to play the shooter on Nintendo’s console. More recently, a modder created an unofficial prequel that was very well received by fans.

Kaan freelances for various websites including Rock Paper Shotgun, Eurogamer, and this one, Gamesradar. He particularly enjoys writing about spooky indies, throwback RPGs, and anything that's vaguely silly. Also has an English Literature and Film Studies degree that he'll soon forget.