Kickstart RT from NVIDIA makes Ray Tracing integration in games easier

At GDC the NVIDIA team had plenty of announcement, most of them not interesting to us but Kickstart RT definitely jumps out. A new SDK under the open source MIT license allowing game engine developers and games to integrate Ray Tracing a lot easier.

NVIDIA say it's the "one stop shop" when it comes to adding "real-time ray-traced reflections, shadows, ambient occlusion and global illumination under one umbrella". Available cross-API and cross-platform with support for Vulkan, Direct3D 11 and Direct3D 12. Plus, support for Linux and Windows too.

This SDK aims to achieve higher quality reflection and GI rendering than traditional screen space techniques, using hardware ray-tracing functionality without having to set up shaders and shader resources for ray-tracing.

When implementing ray-tracing into an existing game engine, one of the biggest problems is preparing the shaders for reflection and GI rays. All of the countless shaders that exist in a game scene must be listed and configured. We also need to make sure that the various shader resources (ConstantBuffer, Texture, etc.) can be accessed correctly from those shaders for each material. This can be a very complex task.

Instead of setting up all the shaders, this SDK takes the lighting information from a rendered G-Buffer and stores it in a world space cache. Therefore, the application does not need to modify any shaders for ray-tracing. Internally, the SDK creates reflection and GI information by sampling the lighting information using ray-tracing. This is the biggest difference from screen space based techniques as lighting information for off-screen objects will also be sampled if it is stored in the SDK.

However, they also make it clear it's not a complete and direct replacement for ray-traced reflections or GI. It comes with some compromises like not taking the material of a surface into account and some latency involved due to the way it works and how it gets updated lighting information.

Kickstart RT is available on GitHub.