Larrabee will use rasterisation in games, not ray tracing

Posted at: 4:07am 24th April 2008 by Ben Hardwidge

Blogger working as a software engineer for Intel confirms that Larrabee will be great for real-time ray tracing, but that it will still use the traditional rasterisation pipeline in games

There’s been a lot of talk about Larrabee since it was slyly announced at IDF last year. Will it revolutionise the gaming graphics industry with real-time ray tracing? Will games developers have to redesign all their engines from scratch to accommodate it? The answers, it appears, have now come from blogging Intel software engineer Tom Forsyth, who is working on Larrabee. Forsyth confirmed that the chip will only use rasterisation in standard Direct3D and OpenGL games, making it a direct competitor to Nvidia and ATI’s GPUs.

‘There's only one way to render the huge range of DirectX and OpenGL games out there,’ says Forsyth, ‘and that's the way they were designed to run - the conventional rasterisation pipeline.’ This, says Forsyth, ‘has been the goal for the Larrabee team from day one.’

Larrabee takes a very different approach to the graphics pipeline when compared to traditional GPUs, using a bank of x86 processors, rather than simple scalar stream processors. This has led many to speculate that the chip could be used for real-time ray tracing, and Forsyth confirmed that this will be one of the chip’s best features.

‘There's no doubt Larrabee is going to be the world's most awesome ray tracer,’ says Forsyth, ‘but that is cool stuff for those that want to play with wacky tech. Forsyth goes on to say that ‘Ray tracing on Larrabee is a fascinating research project, it's an exciting new way of thinking about rendering scenes.’ However, he added that ray tracing ‘is absolutely not the focus of Larrabee's primary rendering capabilities, and never has been - not even for a moment.’

In short, it looks as though Larrabee will be capable of real-time ray tracing, but for the moment Intel’s main target is making it an efficient rasterisation GPU in Direct3D and OpenGL games. The important point here is that Larrabee will not add ray tracing to Direct3D and Open GL, but could be capable of it using alternative APIs. That said, Forsyth did confirm that Intel has some plans to change the rendering pipeline ‘beyond what people currently know,’ but that the changes would be ‘a lot less radical than ray tracing.’