DirectX raytracing (DXR/RTX from Microsoft and Nvidia) and future of GPU rendering.


Microsoft is announcing DirectX Raytracing (DXR) which is meant to popularize Raytracing effects for games, while Nvidia goes even further by introducing RTX and Raytracing for Gameworks, a hardware/software raytracing solution built to enhance DXR, including a dedicated raytracing chip on upcoming Volta cards (and denoisers out of the box).

This is big news for us. Up until now, dedicated raytracing cards were a niche product, mostly unsupported by any renderer, but if it goes “mainstream” (Unity, Unreal, Frostbite are planning integration), and gets popular for games, we’ll get better and better dedicated raytracers on board of the next generations of cards, and the GPU renderers will directly benefit from it.

Nvidia is first, but AMD is on board of DXR too, apparently, so hopefully this will translate in better Radeon ProRender performance too in the future.

After out of core memory, geometry and AI enhanced denoisers, this might be the final nail in CPU rendering.


It certainly merits keeping an eye on. I was a little underwhelmed with the demo video. All this will certainly be tuned for gaming so I’m not sure if it will impact our work…or not.

But we all can see where this is headed. It’s just a matter of time.


Although this is very interesting, it sounds like it will not help to make things more platform agnostic. But maybe there will be something similar in OpenGL…?! However I am not aware of any initiative in that direction…
AMD will mainly implement DXR in ProRenderer, which sounds like a pretty direct path into Cinema 4D: more info @ anandtech
DXR info


Yes at the moment it’s a very “Microsoft/Nvidia” initiative meaning it’s PC only. AMD cards will not have hardware acceleration yet, but they say they have superior compute performance out of the box (=hence cryptominers. craze…), and it seems logical to think they will want to play catch up with Nvidia (especially considering the direct benefit to Prorender).

I think this is similar to what happened with PhysX technology : at first it was all on the CPU, then the Ageia PhysX guys made some dedicated hardware that was interesting but nobody really bought, until Nvidia took it all and added it to their Geforce cards, at which point it became a commodity.

Sadly though, unless an OpenGL equivalent (pushed/financed by whom? AMD? Does Apple even care?) surfaces, Mac users will most likely not benefit from it in the short term (not that I use Mac myself, but this means a big chunk of C4D users will not be able to use it, hence no DXR/RTX viewport or renderer in the foreseeable future from Maxon).

This being said, if next year or so, most of the new cards have hardware raytracing acceleration capabilities, third party vendors like Redshift, Octane or even Cycles will certainly jump on board and we might see some significant speed boosts (it’s already impressive enough with Octane 4 without dedicated raytracing HW, let’s see what it will become next…)

Edit : Added AMD’s own initiative :

[quote=]AMD is announcing Radeon™ ProRender support for real-time GPU acceleration of ray tracing techniques mixed with traditional rasterization based rendering. This new process fuses the speed of rasterization with the physically-based realism that users of Radeon ProRender expect for their workflows. At a high level, the process achieves these results by using rasterization to draw basic structures and surfaces before a ray tracing process is used to compute advanced light-effects like reflections, shadows and transparency. The flexibility of the process allows users to decide when these advanced light effects are actually necessary and add noticeable new dimensions of realism to their renders.[/quote]](


What RTX appears to be - largely - is:

  1. Drawing a regular, fast-shaded DirectX 3D raster frame with the GPU.
  2. Firing ray tracing rays into that raster render, and the 3D data generated during that raster render.
  3. Pretending - for marketing purposes - that denoising this and so on and so forth this requires “highly sophisticated algorithms”, bla bla bla.

Precisely what is in Microsoft DirectX 12 or Nvidia RTX that the OpenGL people or AMD cannot do as well?

Do you really think that either Microsoft or Nvidia invented some amazing new technology to make this happen?

I can assure you that OpenGL and similar will be able to realtime ray trace pretty soon as well.

They are probably already working on it.


Impressive DXR/RTX demo :