Imagination mulls adding DirectX to its GPU roadmap amid customer interest

For now, here's an IMG CXT processor with real-time ray-tracing abilities


Imagination Technologies says supporting DirectX is becoming a bigger consideration for the company when it comes to designing GPUs.

"We've definitely been speaking to a lot of customers around DirectX; it's something that, looking forward, for sure [is] for the roadmap. Obviously it's a big investment, and something that our customers clearly think is very important," Andrew Girdler, product manager at Imagination, told The Register.

The design house's heritage is in embedded and mobile graphics processors, particularly for Android devices and other Linux-based systems. Support for DirectX, which is the primary low-level graphics and multimedia framework used by games on Windows, is becoming a consideration as Imagination tries to break through into the PC market with more capable GPUs.

To that effect, Imagination – which like Arm designs chip parts for customers to license – today announced a flagship GPU called IMG CXT, the first in its C-series of GPUs. It is claimed the design will bring desktop-grade 3D rendering and graphics to mobile devices.

A core feature of the CXT is support for modern-era real-time ray tracing, which will give Imagination's portfolio of graphics processors a "step up in terms of that sort of visual experience," and "add nice reflections, nice shadows on top of premium mobile games," Girdler said.

"We can do more advanced effects as you see in high-end desktop GPUs. We can do that in such efficiency that you can bring that down into the mobile space," he explained.

One of Imagination's main customers is MediaTek, which wants to see Windows 11 running officially on its Arm-based system-on-chips so that it can sell those components to mobile PC makers. MediaTek's processors are currently in Chromebooks, which run Google's Chrome OS operating system.

Windows 11 on Arm right now only officially runs on Qualcomm system-on-chips, which do support DirectX. A future Imagination GPU with DirectX support would be a boon for system-on-chip makers, like MediaTek, hoping to see Windows 11 run on their components.

Today's Xbox and PlayStation consoles, and PC GPUs from AMD and Nvidia, already have real-time ray tracing for demanding games. Imagination hopes its ray-tracing implementation will move its mobile-spec GPUs deeper into the PC space, much like how Qualcomm got its mobile chips to power Windows PCs.

"We can run a lot of this content today already through Vulkan and through these translation layers. We're scaling towards these higher performance points as we go. As you get some of these performance points, you start to look more at DirectX," Girdler said.

Imagination competes with the likes of Arm, Qualcomm and new entrant AMD, whose GPUs are scheduled to be in Samsung's mobile chips. The C-series ray-tracing intellectual property, called Photon, can also be licensed by chip designers to integrate into other GPUs.

The CXT graphics core delivers 1.5 teraFLOPS of 32-bit floating point performance, and 6.0 TOPS of AI performance, according to Imagination. For desktops and servers, multiple GPU cores can be linked together for better graphics.

Imagination's ray-tracing feature is designed to operate within the power budget of mobile devices. The tech takes into account the scene and locations of objects, and shoots out rays for shadows, reflections, and the global illumination system.

"We'll then do things like de-noising which is similar to what's done in the desktop market, but you're doing de-noising to kind of try and smooth these effects out and keep them looking clean and consistent because we've not got that huge ray budget," Girdler said.

The company avoided a brute-force approach to ray tracing, which involves firing thousands of rays to improve graphics. The ray-tracing tech analyzes scenes and schedules firing off rays, and dedicated hardware tracks updates and makes sure that all of the data is kept accurate.

A separate "ray store" is dedicated storage that keep all of the data being processed on the chip instead of storing it on DRAM. A coherency gathering unit looks into the ray store, tries to find groups of rays that are all traveling in a similar direction, and find rays that can be parallelized effectively.

"You end up doing sort of, OK, here's one ray. Let's test it. Here's another ray. Let's test it. We're looking to find rays traveling all together, batch them into groups of up to 16 and then test them all in parallel. And that gives us a big improvement in terms of efficiency," Girdler said.

Imagination is finding other applications for graphics in data centers, automotive products, and on the edge. The ray-tracing feature could be built inside car chips around data from cameras and sensors, like LIDAR, to generate photorealistic renders of a car in real time on the dashboard. ®

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