UPDATE 20/4/20 2:00pm: What better way to learn more about Minecraft RTX than meeting up with key developers behind the game itself and discussing the work they did in transforming the game with the power of hardware accelerated ray tracing?
In this Digital Foundry video special, Alex Battaglia takes a tour of the Minecraft RTX beta with the people that created it. You'll get to see more of the stunning effects that Minecraft RTX has to offer, how the game has evolved since its Gamescom 2019 debut and the plans the team has in pushing quality and fidelity still further.
Many thanks to the Nvidia staff who participated in this video - Oli Wright, Jakub Boksansky and Paula Jukarainen (developer technology engineers at Nvidia) and Jaakko Haapasalo (producer, GeForce titles).
Original story: Users of Nvidia's RTX graphics cards are in for a treat today: a beta version of the fully path-traced version of Minecraft is available, giving users unfettered access to a version of the game running under the DirectX ray tracing API. In combination with the launch, key Minecraft creators have teamed up with Nvidia to showcase path tracing to spectacular effect, with six bespoke maps available to download from the Minecraft marketplace. On top of that, this release also sees the debut of physically based materials. Downloading any one of the creator maps released today automatically adds these textures into the game, but users can also create their own materials and 'side-load' them into the game.
Let's not mince words here - path tracing in Minecraft is one of the most transformative uses of ray tracing we've seen. While the core visuals themselves are rather simplistic (it is Minecraft after all), this means that there's a surfeit of GPU power that can be reployed into pushing ray traced effects to extreme levels. Most RT-enabled games use a combination of standard rasterisation techniques with ray tracing features on top - hybrid rendering, if you like. In Minecraft RTX, everything is ray traced: every element is realistically, correctly lit - and as you'll see in the embedded video below, the extent of this implementation produces effects we've never seen in games before.
Of course we have seen different flavours of ray tracing in Minecraft attempted already, kicking off with an initial rendition for the Java version of the game that may well have served as an inspiration for the 'real deal'. However, while impressive as a starting point, it still used rasterisation for the geometry and for the first bounce of light, and as a consequence, shadows weren't ray traced either. All skinned objects were also rasterised, so screen-space reflections and screen-space global illumination were blended in to cover models and transparencies like grass. Effectively, only the bounce lighting was path traced, and only from the blocks.
In stark contrast, virtually everything in Minecraft RTX is path traced, and the execution here is next-level stuff - even when stacked up against Nvidia's own work with Quake 2 RTX. Hardware acceleration allows for a far greater degree of fidelity, and the traversal of light can be mapped across many more bounces for even more remarkable effects. A temporally-based 'irradiance cache' maps the traversal of light across multiple frames, allowing for up to eight bounces of light, allowing for a 'hall of mirrors' effect when multiple reflective surfaces are in play - even spoon-like reflections are possible. On top of that, voxel-based volumetric lighting is integrated with path traced lighting for some deeply impressive god ray-style effect.
Of course, we've seen an offshoot of this DXR version of Minecraft play out in an Xbox Series X tech demo, where at native 1080p resolution, the new Microsoft console delivered variable frame-rates north of 30fps. An ambitious ray tracing solution demands a lot of GPU muscle and as you would expect, the same is true of the Minecraft RTX beta. That's where Nvidia's DLSS 2.0 technology helps out in ensuring that any RTX graphics card can still deliver a high frame-rate experience.
It's usually the case that multiple quality modes are available in DLSS 2.0-enabled titles, but things are pared back for the beta - something which we hope is a temporary affair with full functionality rolled out for the final game. As things stand right now, output resolution is established by your choice of desktop resolution (in common with many of Microsoft's DX12 efforts) and from there DLSS reconstructs from a pre-defined lower resolution. So effectively, 1080p DLSS reconstructs from 720p, while 1440p upscales from 835p. Moving up to full 4K, this is reconstructed from a native 1080p. These figures may sound low, but we've talked in the past about how effective Nvidia's new AI upscaling algorithm is - and with Minecraft's relatively simplistic aesthetic, DLSS 2.0 easily passes for native resolution rendering.
Consequently, there are few issues running the Minecraft RTX beta on any desktop RTX card and to get a flavour of overall performance across the stack, we tried out the beta on the extreme ends of the RTX stack. The takeaway is that an RTX 2080 Ti can run 4K DLSS at 60fps on most content (we only saw drops into the 50s moving underwater), while 1080p DLSS on a desktop RTX 2060 produces equivalent performance. The only potential issue we could see would be in running Minecraft RTX on the laptop version of the RTX 2060 - which is a fair chunk slower than its desktop equivalent (a native 540p DLSS performance mode that resolves at 1080p should address this, however). In short, Minecraft RTX delivers the best of both worlds - you get to see the hardware accelerated version push the envelope in terms of fidelity, while Nvidia's brand new AI upscaling tech does a really good job of mitigating the performance hit.
The only other factor worth commenting on is that path tracing isn't just computationally expensive - it's demanding on memory too. The RTX 2060 possesses 6GB of GDDR6 VRAM, which is fine for 1080p DLSS rendering, and while 1440p performance worked out Okay bearing in mind the additional pixel-count, hopes of a 4K30 experience were dashed. In this scenario, we saw a lot of stutter as the game maxed out the available memory. To run at 4K with consistent performance, an 8GB RTX card is recommended.
The Minecraft RTX beta is available now (download instructions here) and we've had a lot of fun with it. As you'll see in our embedded video, just using Minecraft's tools to experiment with the way light is rendered in the game throws up all manner of fascinating effects - we even got a pinhole camera effect working. Meanwhile, the six creator maps serve to show what the path tracing effect can deliver when full-on Minecraft levels are specifically built around the new rendering technology. Nvidia tells us that over 15m RTX cards have shipped by this point - so if you're one of those users, we highly recommend checking out this beta.