These days, everyone is talking about ray-tracing and RTX when it comes to graphics cards and PC gaming. However, all the games at present leverage Microsoft’s DirectX12 API to enable this technology. Wargaming, developer of World of Tank has taken an alternative route to enable ray-tracing in one of their games: Intel’s Embree library.
Embree is part of Intel’s One API and supports all DirectX11 graphics cards. World of tanks enables ray-traced shadows on all graphics cards, both NVIDIA and AMD without needing the RTCores found in the RTX 20 series cards. According to Wargaming, the quality will be very close to that rendered by NVIDIA’s RTX cards in supported games. However, due to performance constraints, only the tanks will cast ray-traced shadows.
Let’s dig in. Without dedicated RT cores how does this work and that too while offering compelling performance. Well, the answer isn’t as complex as you’d have thought. Dubbed Encore RT by Intel, this form of ray-tracing offloads the actual work to the CPU cores.
One of the main steps involved in ray-tracing is BVH: Bounding volume hierarchy. It essentially accelerates the whole process. All the objects in the scene are enclosed in multiple boxes of sorts called Bounding Volumes. Then instead of each primitive (or triangle), these boxes are exposed to the rays coming from the camera. If the rays intersect the enclosure, then the object inside will be visible, if not then it won’t. You also have to consider which BVs intersect each other and accordingly render the scene.
In Intel’s Encore RT, the BVH part is done by the CPU cores instead of the GPU. As per Intel, their CPUs are optimized for Embree, but unlike RTX this is a free source and not a proprietary library. Furthermore, AMD’s chips are said to perform better in this form of ray-tracing than Intel’s own 9th Gen Coffee lake CPUs. You see something new every day, don’t you?