CHIP DESIGNER Intel has released specifications for three graphics extensions that will appear in the GPU of its upcoming Haswell processors.
Intel's upcoming Haswell processors will largely retain the same HD Graphics 4000 core found in the firm's Ivy Bridge chips, however there will be new features that will allow the firm to claim some technological advances. The firm announced the first of those changes at the Games Developer Conference (GDC) with DirectX graphics extensions.
Intel revealed some details on its Pixelsync and Instantaccess technologies, claiming its introduction at GDC rather than later will help games developers take advantage of the technologies when chips appear.
Intel's Pixelsync allows developers to composite partially transparent pixels without having to enter further subroutines. The firm claims this will allow developers to render more realistic textures.
Intel also announced Instantaccess, where the CPU and GPU can read and write to the main memory. Intel didn't mention it by name, but given that Intel's HD Graphics 4000 supports OpenCL, giving read and write access to system memory to both CPU and GPU is edging towards having a unified memory architecture.
While Intel allows for the CPU and GPU to access main memory, it didn't reveal the addressing scheme, which is important from a developer's viewpoint. Nevertheless slowly but surely, Intel is seemingly edging towards GPU computing, even publishing a whitepaper supporting heterogeneous system architectures.
Intel's GPUs might be the butt of gamers' jokes but the firm has been the largest PC GPU supplier by far for many years and is often used as the benchmark for mass market games. Therefore, what the firm includes as part of its GPU specifications determines what many games will look like for a number of years.
All of Intel's posturing with its HD Graphics extensions strongly suggests that the firm is preparing its Haswell announcement sooner rather than later.
The software side of PixelSync is an evolved version of Intel's own Order Independent Transparency algorithm that leverages high quality compression to reduce memory footprint and deliver predictable performance. Intel has talked a bit about an earlier version of this algorithm here for those interested.
Intel claims that two developers have already announced support for PixelSync, with Codemasters producer Clive Moody (GRID 2) appearing in the Intel press release excited about the new extension. Creative Assembly also made an appearance in the PR, claiming the extensions will be used in Total War: Rome II.
The second extension, InstantAccess is simply Intel's implementation of zero copy. Although Intel's processor graphics have supported unified memory for a while (CPU + GPU share the same physical memory), the two processors don't get direct access to each others memory space. Instead, if the GPU needs to work on something the CPU has in memory, it needs to make its own copy of it first. The copy process is time consuming and wasteful. As we march towards true heterogeneous computing, we need ways of allowing both processors to work on the same data in memory. With InstantAccess, Intel's graphics driver can deliver a pointer to a location in GPU memory that the CPU can then access directly. The CPU can work on that GPU address without a copy and then release it back to the GPU. AMD introduced support for something similar back with Llano.
Building on top of the existing DirectX 11.1 development language, Intel has created two driver extensions that are designed specifically to take advantage of the GPU found inside 4th Generation Core processors. The first, PixelSync, allows game creators to create effects using Order Independent Transparency - one of the "Holy Grails of real time graphics" according to Huddy.
By sending data through the pixel pipeline in a specific order, rather than randomly, it's possible to render more realistic smoke, hair, windows, foliage, fences and other complex geometry without the huge computational overheads needed to do so using random data. According to Intel, enabling OIT results in a 10% performance hit, versus 80% on traditional graphics cards.
The first developer to take advantage of PixelSync is Codemasters, adding OIT effects to racing simulation Grid2. Apparently, having accurately lit glass, smoke and dust is a feature that was high on the wish list for the company, but until now had proved impossible.
“The artists working on 'Grid 2' have been requesting this type of effect for years, and prior to this, it wasn’t possible to achieve it at a reasonable cost,” said Clive Moody, senior executive producer at Codemasters Racing. “The fact that this capability will be available to millions of consumers on forthcoming 4th generation Intel Core processors is very exciting to us.”
Intel was showing off PixelSync on Grid 2, which is an upcoming racing video game, currently under development by Codemasters.
The game played smoothly at 1920x1080 and when smoke was in the scene it did look good.
The Intel demo was performed on a laptop, but that is all we really know. Intel was not talking product names, part numbers, performance figures or anything here at the show. So, we now know that Intel Haswell processors have a pair of DirectX extensions that some game companies will be using in upcoming game titles, so get ready for integrated graphics to have features that your discrete card can't do! Never thought we'd ever say that!