John Carmack Interview: GPU Race, Intel Graphics, Ray Tracing, Voxels and more!

Ray tracing, unique PC gaming features and more

On the topic of ray tracing, a frequently debated issue on PC Perspective, Carmack does admit to finding its uses quite surprising and has spent some time building ray tracing engines for development testing. He seemed surprised by the results in his initial attempt to replace rasterization with a ray tracing engine, getting as much as 60 FPS at 720p resolutions on a Fermi-based NVIDIA graphics card. When performance dropped below the targeted frame rate he was able to either produce an image of a lower resolution and display that or use previous frames to sort of “blend” them for a smoother image. The issue though is the delta between a tech demo and fully implemented gaming engine – demos deal with static models, there is no character animation, etc. And while the fact that it runs at 60 FPS at 720p sounds impressive, if you were drawing that with a traditional rasterization engine it would be running at 1000 FPS!

Intel ray tracing demo

Interestingly, Carmack discussed using ray tracing and x86 CPUs for the back end processing and mega-texture generation on RAGE. While performance per watt and per processor was still better using the GPGPU implementation id Software created at the beginning of development, the fact that development, maintenance and upkeep were significantly easier when using the x86 ray tracing method made the decision easy for him. In short, he says “in terms of results per developer hour, it is much, much better.”

Now to things of recent debate – infinite detail engines. He first clarifies that voxel engines and infinite detail topics are not the same thing and should not be treated as such. Carmack then states he believes “procedurally generated detail is usually not what you want.” A discussion that has been around for over a decade, truly useful procedurally generated content has never materialized though the ability to easily and efficiently manage the real data that you do create HAS. My favorite line? “Proceduralism is just a truly crappy form of data compression.” He continues to state that infinite detail isn’t really what’s important to future game development and instead we should be focusing on the “broad strokes” of artistic visions and build on them. “If you take uninspired content and go look at it at the molecular level, it’s still uninspired content.”

Screenshot from Euclideon Unlimited Detail Engine

After discussing some of the interest in voxels and that the next step in development is to “geometrify” everything, Carmack mentions that he thinks eventually, ray tracing will win the rendering wars. Keep in mind that much of rasterization is built on decades of hacks – something we discussed in our previous interview with John. Where he is not sure on the path of development is on whether ray tracing into dense polygonal geometry or ray tracing into voxels will be the best method. Both have advantages but even with all the development going into voxels today, Carmack doesn’t see an engine for a “major AAA title” using it for quite some time.

Tessellation was discussed as well and Carmack agrees that the technology can have some value as long as it is implemented at the ground level of development. Bolting something on after the majority of a game is built won’t really do anything to benefit the gamers and will only be a check box feature. Tessellation at today’s performance levels will help with basic structures like the curve of a skull, but Carmack contends that the size of structures that developers are currently using normal maps for (fine grain in textures, etc) are not appropriate for current implementatons of tessellation hardware and that is where the benefit will truly be seen. We don’t quite have the tessellation power to render the entire world at sub-pixel sized triangles yet but that is coming, almost inevitably.

I asked John about the possibility of seeing Eyefinity/Surround support on RAGE and while he said that isn’t currently enabled, there are some research engines he has developed in house that he would like to see released as “novelty patches” like we were used to seeing in the old days. After RAGE is out the door he plans on playing with Eyefinity, Kinect SDK and even head mounted displays and we are definitely hoping to get some feedback after he spends some time with them.

We hope to see some Eyefinity / Surround support in RAGE and Skyrim

Will there be any kind of benchmarking or testing modes in the pending release of RAGE? Not yet but he is hoping in the next month that they’ll be able to integrate some kind of artificial scene to display and output results from so gamers will be able to easily know if they can run at higher settings.

There was an interesting talk about the id Tech 5 engine and how it will be licensed – it won’t! In fact, only the ZeniMax family of developers will be able to utilize the engine to build new games. For modders, Carmack stated that they were going to release the 64-bit version of tools though there is going to be a limit to what people can do with it because there is a lot of infrastructure involved with the mega-textured worlds. Expect to build new gaming characteristics and multiplayer modes, but not much more than that for now. Keeping in mind there is over a 1TB of source material to build RAGE, they can’t possibly put that all up for download.

RAGE is coming October 4th!

Finally, we asked about his opinions and thoughts on the upcoming release of Skyrim and Carmack stated that it was interesting to see how easily they could integrate some of the adventure game features in future titles without detracting from other aspects of gameplay. And because id Software is essentially on the same team as Bethesda now, the “masters of the craft” as he calls them, it would seem likely we’ll see a merger of these types of ideas in upcoming titles.

There are a lot more details in our full video interview on the previous page so make sure you give it a listen/view – at only 32 minutes long you would be hard pressed to get more information in such a short time span.

I would again like to thank John Carmack and Angela Ramsey for blocking off some time with us during the busy Quakecon schedule! We love the work they are doing and can’t wait to see what the id Software and Bethesda teams have for us in the future!

You can follow Ryan Shrout on twitter @ryanshrout and John Carmack on twitter @ID_AA_Carmack.

For more from John Carmack at Quakecon 2011, be sure to check out his keynote and follow up Q&A videos.