Thoughts on RTX Rendering

I wonder what the RTX cards will bring in two weeks. That is a feature that would make Eevee comparable to Cycles.


RTX is mostly accelerating Microsoft DXR and their Optix Denoiser and Raytracer.
First Clement F. must must switch to Vulkan to make some nice Realtime Raytracing additions for EEVEE possible.

According to his dev log he already started but it will take a while.
Hope it gets some more prio because one of next big things.

Do you guys thinks that the blender 2.8 rtx demo at siggraph is for the NVIDIA show ?

At the least, RTX should be useful for Eevee soft-shadows, reflections, and multi-layered refractions, most of the game engines are currently using raytracing in a limited capacity anyway.

It’s nice to also have this on the Pascal cards at least (even if it will be a bit on the slow side). The reason I settled with just a GTX 1060 6GB card last year was because I didn’t want to splurge when I knew of the inevitable new models from Nvidia. Maybe the “Super” cards will have a bit of utility then.

Cryengine made a demo awhile back using an old AMD Card Vega 56, u don’t need RTX to do ray-tracing, i think the focus should be on Vulkan implementation before ray-tracing unless Nvidia generously donates for developers to work on their Cards.

Time to open the floodgates and transition Blender was “that open source 3D software” to a force to be reckoned with. Ton’s new message.

Blender is in a transition phase - with more professional demand from
users we also need to improve the quality of our projects on Not only to support more full-time developers, but also
(especially) to improve access to our project for everyone - for
volunteers and professional developers alike.

That means better tech docs, onboarding, reviews, coordination,
communication, triaging, developer support, code standards, roadmaps,
tasks, planning, work with active users… just anything that will help
everyone to function more pleasantly to contribute to Blender’s source
code or to come on board as contributor. We’ve often had complaints
about not being accessible enough. Time to work on this.

Nathan Letwory started this discussion already with the thread
“Understanding the dev process”. A lot of good feedback has been offered
already. Let’s keep doing that the coming months.

I am working on a more complete Development Fund report and blog post on, also to talk about additional grants for developers
and job openings. Obviously the dev fund is now big enough to also
support more dedicated development targets - such as Cycles, VSE,
Sculpt/Paint, modeling, particles, ‘everything nodes’, etc.


That sounds good, BF needs new blood. :wink:

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Yup, it seems to me that RTX is a classic case of the triumph of marketing over technology.

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Raytracing is a lot faster on RTX cores though, because that is exactly what that type of hardware is engineered to do. You can do the same thing on CUDA cores, but you will find your card unable to trace at interactive speeds. It’s the same story with AMD’s compute cores, though they redesigned them for Navi so maybe they can close the gap some.

The more questionable bit is the Tensor cores. They are supposedly engineered specifically for AI calculations, but the DLSS Nvidia showed off shows it’s actually their supercomputer that does all of the hard work and the tensor cores just crunch the resulting neural net.


I have no insider knowledge here, but my guess would be that someone has been working on getting basic RTX support into Cycles. I will be really surprised if it’s Eevee they’ve been working on (but hey, what do I know?)

RTX support would be cool if you’re in the minority of users who own RTX hardware, but the thing that makes me not jump up and down with excitement is that it’s “just” a performance improvement and likely does not provide any quality improvement (apart from maybe you can turn up the knobs and render in the same time as before). I’ll also be surprised if it makes a Cycles render more than double the current speed when you have complex materials etc. that can’t do anything with the RTX hardware.

It also potentially complicates the development and testing of Blender if the developers and test processes all want to have access to RTX compatible hardware, and if there’s any duplication of code between RTX and non-RTX kernels and everything has to be tested both ways all the time (Nvidia of course would tell you to just write all your code to require their API and not worry about piddly details like supporting non-Nvidia hardware).

Cycles typically computes hundreds, even thousands of light rays per pixel. Correct me if I’m wrong, but RTX seems to do one or two at most, and then papers over the cracks with heavy use of denoising.

How can RTX help with Cycles rendering, again?

That is how people use it in games, but that’s not what RTX forces. RTX is a black box - you give it a mesh and a bunch of rays and it returns if and where the rays intersect the geometry. What you do with it after that is entirely up to the application.


Hi, Otoy publish a benchmark with Octane and RTX support, results are 2-5 times speedup:
You can’t compare engines directly but you get a hint of what is possible.

Cheers mib