Today NVIDIA unveiled their RTX technology which essentially, is ray tracing hardware acceleration for Volta and later GPUs. NVIDIA hasn’t detailed how the backend for DirectX raytracing will work, but we reckon that will be detailed when Volta is officially unveiled.
Alongside RTX, NVIDIA also announced their new GameWorks ray tracing tools, for rendering high quality ray traced shadows, reflections and ambient occlusion. These tool are already available to NVIDIA’s close partners in early access phase.
While Volta will support RTX and DX Raytracing on a native level with hardware acceleration for the same, for older architectures it’ll be enabled via a mix of API fallback option and the drivers. Here, the compute shaders will do the job, although I’m guessing it’ll be nowhere as efficient.
A number of other developers and game engines are supporting RTX and DirectX Raytracing at GDC 2018. The important ones being EA, Epic, Remedy, 4A, etc.
You might or might not know this but raytracing has been around since forever. It is as accurate as it gets, with reflections, shadows and lighting being it’s strongest aspects. Raytracing involves sending a ray from the viewer and this ray interacts with the objects on the screen, thereby calculating reflections, refraction, shadows, etc.
This happens for each pixel on screen, and so it’s very taxing on the hardware. As a result it was replaced by a more cost effective rendering method, rasterization. To read more on this go here.
On the downside, rasterization can’t keep up with raytracing in terms of quality. So now this is an attempt by Microsoft and NVIDIA to find the middle ground by combining the two and get a good balance of quality and performance. That’s what RTX and DX raytracing are all about.
Unfortunately, as already mentioned, not many technical details are being disclosed, making it difficult to say how RTX is different from DirectX Raytracing or if it’s the same. NVIDIA only confirmed that some Volta does accelerate ray tracing, and that RTX is a mix of both hardware and software.
NVIDIA also brought up Volta’s tensor cores, saying that they can be used to accelerate ray tracing by leveraging AI denoising. Here a neural network could be trained to reconstruct an image using fewer rays, reducing the cost of raytracing.
As for the new GameWorks Ray Tracing tools, NVIDIA mentioned the ray-tracing denoiser in NVIDIA GameWorks, including ray tracing libraries for area shadows, glossy reflections, and ambient occlusion.
For possible ray tracing acceleration on pre-Volta architectures, NVIDIA pointed to the fallback option in DXR. As per NVIDIA real time ray tracing with RTX on Volta will be “integer multiples faster” than with DXR on older hardware.
NVIDIA also said that the tools had been provided to certain developers a few months ago, and that we should expect games supporting RTX and DirectX Raytracing to ship later this year. While, the RTX technology will only be available on Volta based hardware, older hardware will be able to run these new features. The performance will probably be pretty ugly but that’s very expected. Also, since games supporting RTX launch this year itself, that means RTX demos aren’t very far off. In addition to that, this confirms that the Volta based Ampere or Turing GPUs will arrive latest by Computex in May/June