There’s something a little spicy about an engineer telling the graphics card manufacturers that they were wrong, and the manufacturers telling him to go to hell… even though he was right! 

In the Half-Life 2 20th Anniversary documentary, it was mentioned that Valve had a wish list of technologies, and one of them was lighting. Viktor Antonov, the lead artist on Half-Life 2, had this to say about it: “It was a key feature that the lighting felt very, very realistic and intuitive because of the Source engine and the work, the collaboration between artists and engineers. Ken Birdwell, he was a fan about photography and getting the lighting right.” 

Birdwell left Valve in 2016. The Half-Life website, now only available from the archives, does a great job of summarizing what he did: in-circuit emulators (CodeTap), 3D surface reconstruction (Surfgen), 3D prosthetic design tools (Shapemaker), and satellite networking (Microsoft Broadcast PC), plus he wrote one of the first graphical shells for multiplayer online games for Compuserve Sniper. In the 1980s, he worked for TeleCalc (a B2B software company) and then followed his passion: he studied painting, photography, and animation at Evergreen State University from 1990 to 1994, earning a Bachelor of Fine Arts degree. He later worked on the animation and AI for Half-Life 1 (and came up with the idea for G-Man). For Half-Life 2, he worked on cutting-edge lighting and quickly got to the problem. 

“The math we were using was wrong, and not only that, the math everyone was using was wrong. And when I started to fix it, I realized how bad it was…and then I fixed it, and suddenly everything looked great! I had to go to the hardware guys, the people who made the hardware accelerators, and tell them that the math on their cards was fundamentally wrong. That took about two and a half years. I couldn’t convince the guys, and eventually we hired Gary McTaggart [of 3DFX] and Charlie Brown, and those guys had enough clout and enough… I’m an art major, nobody’s going to listen to me,” says Birdwell. 

He also explained in technical terms what exactly the problem was: “It’s a little technical, but the simple version is that graphics cards at the time were always storing RGB textures and even displaying everything as non-linear intensities, meaning that an 8-bit RGB value of 128 encodes a pixel that’s about 22% as bright as a value of 255, but the graphics hardware was doing the lighting calculations as if everything was linear. The result was that the lighting always looked off. If you tried to shadow something that was curved, the dimming would get darker far too quickly due to the angle of the surface pointing away from the light source. Just like in the example above, something that was supposed to look 50% brighter at full intensity ended up looking 22% brighter on the display. It looked very unnatural, instead of a nice curve everything was shaded way too extreme, rounded shapes looked weirdly exaggerated, and there was no way to get things to work in the general case.” 

This is not a problem today with GPUs, but back then it was! Birdwell explained how the manufacturers’ approach was a problem because he was considered an artist: “Throughout the ’90s until maybe the early 2010s, that wasn’t the case. You had to be super aware of what ‘gamma space’ you were in every step of the process or things would look super weird. The problem was, when I pointed this out to the graphics hardware companies in the ’99s and early 2000s, I got the “you just pointed out that my chips are fundamentally broken until we design brand new silicon, I hate you” reaction. It wasn’t a fun conversation. It went through the stages of denial, anger, bargaining, etcetera, all in rapid succession with each new manufacturer. I was very happy to hand off those conversations to the newly hired HL2 graphics programmers, McTaggert and Brown, who worked through it all step by painful step over the years.” 

Birdwell, by the way, has an unrelated patent issued to Valve in 2007, on which he is listed as an inventor. The patent, #20070195090, is entitled “Determining Illumination of Models Using an Ambient Framing Abstractions”. Its abstract reads “System and method for determining illumination of a model in a virtual environment.” 

Perhaps it’s no coincidence that producer Bill Van Buren said that lighting is one of the most important parts of being able to immerse yourself in the game… 

Source: PCGamer