Ray tracing GPU aims for mainstream mobile gaming
Imagination Technologies has extended its range of graphics processing cores with ray tracing for mainstream mobile gaming.
The D-Series GPU provides allows chip developers to integrate ray tracing into system on chip (SoC) designs to match their design goals from premium to mainstream devices. Imagination already has deals with mobile chip designers as well as automotive and industrial SoC chip designers.
It also brings its RISC-V firmware processor across from the previous BXS automotive design.
The first in the D-Series family, the IMG DXT, scales from an area-efficient half ray acceleration cluster (RAC) configuration up to a high performance four-RAC design. This supports simple shadowing graphics up to premium ray-traced graphics for leading edge games.
The core has 50% higher performance than the previous CXT core and 20% higher performance per area. This translates to improved power efficiency for mobile chips.
The IMG DXT provides support for Fragment Shading Rate (FSR) for the Vulkan graphics API to give developers more headroom for performance. FSR decreases the number of fragments processed and significantly increases graphics performance with minimal impact on visual quality. At the same time, FSR makes ray-traced effects more efficient as fewer rays are sent into the scene, meaning realistic lights and shadows are achieved within a smaller silicon area.
The flagship DXT-72-2304 configuration delivers 72 GTexels/s and 2.5 TFLOPs of FP32 arithmetic performance at 1GHz.
The RISC-V compliant firmware processor, already proven in its automotive BXS range, boosts the firmware performance by up to 40% and includes power domain management with a focus on reducing its idle power, turning off parts of the GPU that are not in use while also optimising performance on casual workloads.
“The growing mobile gaming market comes with a demand to balance low-power use against the desire for realistic and immersive graphics. As industry leaders in efficient ray tracing for mobile, we are accelerating ray tracing adoption and driving ecosystem growth,” said David Harold, Chief Marketing Officer at Imagination.
“Last year, we launched and licensed the first mobile ray-tracing GPU. Our new scalable IMG DXT cores work at multiple levels of implementation, starting with basic graphics integrations, up to flagship SoCs with desktop-level ray-traced visuals. The mobile GPU launches today, and we have already licensed the IP in multiple segments. We are also speaking with lead partners in automotive, desktop and data centre.”
Ray tracing hardware support
The DXT Photon architecture allows variants with single, dual, or quad-RAC configurations and can provide effective ray tracing regardless of the RAC configuration, ensuring DXT offers usable ray tracing at up to 40% lower area cost, compared to the same mobile configuration as CXT.
The fragment shader in a GPU draws the colours from a scene onto the framebuffer. FSR is a technique where the number of times the fragment shader runs is reduced with almost no decrease in image quality as a result. This cuts bandwidth usage and lowers power consumption.
Developers control how aggressively FSR is used, the most extreme mode executes the shader code only once for a 4×4 fragment zone, resulting in a near 94% reduction in workload with matching power and bandwidth benefits. The performance this frees up enables developers to do more with the hardware and offers players a higher-quality gaming experience.
The DXT GPU also implements a new shader processing unit (SPU) design with a triple Universal Shader Cluster (USC) design. The SPU is a silicon block that contains both an arithmetic logic unit (ALU) for compute tasks and a texture processing unit (TPU) for shading pixels, geometry processing and rasterisation logic.
Many new games rely on heavy texture sampling to implement advanced filter effects. The IMG DXT GPU has an innovative patented special mode inside its texture processing unit (TPU) that creates a “fast path” for these post-processing effects. The result is a near doubling of bilinear filtering performance with minimal area growth and an overall reduction in power consumption. It accelerates tasks such as post-processing effects in games and computational photography filter processing. The higher throughput of the GPU also enables improved ray-traced image quality through faster and more power-efficient denoising algorithms.
Software support
Support for ray tracing in software is vital for it to be included in the chips.
Software support in the PowerVR SDK and developer tools enables ray tracing capabilities across the stack with Vulkan RT support included. DXT includes support for a wider range of compression technologies to maximise bandwidth efficiency. This includes Khronos ASTC HDR, enabling textures to have a greater dynamic range between bright and dark areas while retaining detail.
“Imagination is a partner of OPPO in O3DF’s Mobile Device Working Group and we are working closely together to optimise performance for next-gen GPU architectures,” said Hansen Hong, Director of Software Technology Planning at phone maker OPPO. “IMG DXT brings new opportunities to integrate realistic graphics across smartphone ranges, unlocking ray tracing and FSR for more mobile gamers.
