Larrabee will feature rasterisation units

Written by Tim Smalley

April 24, 2008 // 1:52 p.m.

Tags: #engineer #gelsinger #gpu #graphics #intel #larrabee #raster #rasterisation #software #wrong

An Intel software engineer working in the company's visual computing group has revealed that Larrabee will focus on rasterisation, and not ray tracing like some of the marketing bods would have you believe.

"I've been trying to keep quiet, but I need to get one thing very clear," said Tom Forsyth on his personal blog. "Larrabee is going to render DirectX and OpenGL games through rasterisation, not through raytracing."

"I'm not sure how the message got so muddled. I think in our quest to just keep our heads down and get on with it, we've possibly been a bit too quiet," he continued.

Pat Gelsinger's now infamous statement about current graphics architectures based on rasterisation being "no longer scalable and suitable for the demands of the future." at IDF in Shanghai last month is what caused the confusion, Tom, but it's good to know that it was essentially flat out wrong.

"Larrabee's tech enables many fascinating possibilities, and we're excited by all of them," said Forsyth. "But this current confusion has got a lot of developers worried about us breaking their games and forcing them to change the way they do things. That's not the case, and I apologise for any panic.

"There's only one way to render the huge range of DirectX and OpenGL games out there, and that's the way they were designed to run – the conventional rasterisation pipeline. That has been the goal for the Larrabee team from day one, and it continues to be the primary focus of the hardware and software teams. We take triangles, we rasterise them, we do Z tests, we do pixel shading, we write to a framebuffer. There's plenty of room within that pipeline for innovation to last us for many years to come. It's done very nicely for over a quarter of a century, and there's plenty of life in the old thing yet.

"There's no doubt Larrabee is going to be the world's most awesome raytracer. . . . but it is absolutely not the focus of Larrabee's primary rendering capabilities, and never has been – not even for a moment.

"We are totally focussed on making the existing (and future) DX and OGL pipelines go fast using far more conventional methods. . . . We would not and could not change the rendering behaviour of the existing APIs."

It's good to hear that Larrabee's engineers have their heads screwed on the right way, because breaking billions and billions of dollars of investment in software based on rasterisation would be a bad thing for the industry – or at least for Intel, a company trying to break into the discrete graphics market. Ray tracing is not the future of graphics, it's a part of that future – it's just one tool in the developers' toolbox and I know for sure that it's not a Swiss Army Knife or Leatherman.

Larrabee continues to interest me immensely and the picture is slowly coming together – one thing is clear from Tom Forsyth's comments though and that's that Larrabee will not render DirectX and OpenGL applications through an emulator.

Are you excited at the prospects of Intel entering the discrete graphics market? Share your thoughts in the forums.

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