Ray tracing has long been the Holy Grail of gaming 3D. It promises much more photorealistic output than current real-time 3D engines, and is favoured by the film world. But it's very processor intensive, too much for today's hardware. Fortunately, a recent move by Nvidia could make GPU-based ray tracing a reality - and bring it to a game near you in just a few years.

Famous rays

This isn't the first time ray tracing has hit the news. Back at the Intel Developer Forum in April, Intel demonstrated real-time ray-traced Quake 4. But that was running on a pair of quad-core CPUs, and led a few pundits to argue that the end of the GPU was nigh - when processors had enough cores.

But just before Christmas, Nvidia quietly purchased a company called Mental Images. This has stoked interest amongst professional 3D designers, because Mental Images produces Mental Ray, the renderer used by a legion of professional 3D animation applications including Autodesk 3dsmax and Maya, and Softimage XSI. So now Nvidia owns the most widely used professional ray-traced rendering engine.

It has another implication as well, though. Nvidia hasn't explicitly confirmed this, but it has hinted that hardware acceleration for Mental Images' rendering technology is a future goal, and a primary reason for the purchase. In other words, running ray tracing on GPUs.

The first aim of this will be accelerated rendering for professionals. But once that has been achieved, it's not exactly a leap for ray-traced games to run on consumer graphics cards as well. After all, the GPUs inside Nvidia's professional Quadro FX cards are basically the same as those in the GeForces - just optimised for OpenGL, with tighter quality control and much longer warranties.

Even more importantly, the next generation of consoles are expected to arrive in 2011 or 2012. With HDTVs likely to be well bedded in by then, the next generation of consoles need the photorealism to match the HD movies everyone will supposedly be watching by then. Real-time ray-traced graphics would provide that.