This March Microsoft announced DirectX Raytracing (DXR), an extension to DirectX 12 API - DXR will provide a standard API for hardware and software accelerated ray tracing under DirectX.
Microsoft also released D3D12 Raytracing Fallback Layer, a library that emulates the DirectX Raytracing API on devices without native driver/hardware support. The Fallback Layer is a thin layer on top of DirectX shared as an open source library via Microsoft's official GitHub repo. The Fallback Layer uses Compute Shaders to implement DXR functionalities.
For the Sponza sample we've selected a viewpoint to generate as much reflection rays as possible. This test has two different modes, the first mode uses a fully-raytraced pass that shoots primary rays for diffuse lights and recursively fires shadow rays, the second mode utilises reflection rays only to create a shiny perfect mirror ground plane.
The Procedural sample uses special intersection shaders to create analytic/volumetric geometry and iso-surfaces - typical effects found in shadertoy demos.
As the Fallback Layer is in an early prototype stage for DXR don't read too much into these performance numbers. :)
PSU: Cooler Master V1000
MOTHERBOARD: Gigabyte GA-990FX-Gaming
CPU: AMD FX-8370
GPU DRIVERS: NV 391.35 / Radeon Adrenalin 18.4.1
RAM: G.SKILL TridentX 16GB (2X8GB) DDR3 2133MHz
STORAGE: Samsung m.2 SATA 500GB SSD 850 EVO
COOLER: AMD Wraith Cooler
OS: Windows 10 Pro Version 1803 (OS Build 17134.5)
NV GPUs: MSI GTX 980 GAMING 4G / MSI GTX 980 Ti GAMING 6G / MSI GTX 1060 GAMING X 6G / MSI GTX 1080 GAMING X+ 8G
AMD GPUs: Sapphire NITRO R9 390X 8G D5 / Sapphire R9 Nano 4G HBM / Sapphire PULSE RX 560 4G D5 Sapphire NITRO+ RX 580 8G D5 LE