John Carmack talks ray-tracing, hardware physics

— 6:00 AM on March 13, 2008

His game engines may not be as dominant and heavily licensed as they once were, but John Carmack is still an influential member of the game industry. Fresh from their chat with Nvidia Chief Scientist David Kirk, the folks at PC Perspective have had a long talk with Carmack about ray tracing and future technology directions.

Much like Kirk, Carmack doesn't share Intel's belief that ray tracing is the future of game rendering and destined to completely replace rasterization. Instead, he also seems to favor a hybrid approach, and he's already come up with ideas for a ray tracing implementation in his next-generation id Tech 6 engine:

I do think that there is a very strong possibility as we move towards next generation technologies for a ray tracing architecture that uses a specific data structure; rather than just taking triangles like everybody uses and tracing rays against them and being really, really expensive. There is a specific format I have done some research on that I am starting to ramp back up on for some proof of concept work for next generation technologies. It involves ray tracing into a sparse voxel octree which is essentially a geometric evolution of the mega-texture technologies that we're doing today for uniquely texturing entire worlds. It's clear that what we want to do in the following generation is have unique geometry down to the equivalent of the texel across everything.

Despite seeing potential in ray tracing, Carmack goes on to say he feels Intel's direction as far as conventional ray tracing goes is "unlikely to win out." He adds that Intel "may be able to soak the significant software architecture deficit by clubbing it with processing power," but that the company must wow developers and gamers with a good demo—and so far, Intel's ray-traced Quake 4 demos are "previous generation technology [that Intel is] trying to make it look like something that is going to a next-gen technology."

The interview goes on for four pages, so it contains plenty of details, but another nugget of information that caught our eye was Carmack's thoughts on hardware-accelerated physics. With Ageia now in Nvidia's pocket, Carmack expects Microsoft to jump in with a physics API in the future. However, having been critical of early Direct3D APIs, he's not confident the software giant can pull it off. "[Microsoft] probably have some accumulated wisdom about that whole process now, but there is always a chance for MS to sort of overstep their actual experience and lay down a standard that's no good," he says.

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