Path Tracing SDK Save

Real-time path tracing library and sample

Project README

Path Tracing SDK v1.1.0



Path Tracing SDK is a code sample that strives to embody years of ray tracing and neural graphics research and experience. It is intended as a starting point for a path tracer integration, as a reference for various integrated SDKs, and/or for learning and experimentation.

The base path tracing implementation derives from NVIDIA’s Falcor Research Path Tracer, ported to approachable C++/HLSL Donut framework.

GTC presentation How to Build a Real-time Path Tracer provides a high level introduction to most of the features.


  • DirectX 12 and Vulkan back-ends
  • Reference and real-time modes
  • Simple BSDF model that is easy to extend
  • Simple asset pipeline based on glTF 2.0 (support for a subset of glTF extensions including animation)
  • NEE/visibility rays and importance sampling for environment maps with MIS
  • Basic volumes and nested dielectrics with priority
  • RayCone for texture MIP selection
  • Basic analytic lights (directional, spot, point)
  • RTXDI integration for ReSTIR DI (light importance sampling) and and ReSTIR GI (indirect lighting)
  • OMM integration for fast ray traced alpha testing
  • NRD ReLAX and ReBLUR denoiser integration with up to 3-layer path space decomposition (Stable Planes)
  • Reference mode 'photo-mode screenshot' with basic OptiX denoiser integration
  • Basic TAA, tone mapping, etc.
  • Streamline + DLSS integration


  • Windows 10 20H1 (version 2004-10.0.19041) or newer
  • DXR Capable GPU
  • GeForce Game Ready Driver 531.18 or newer
  • DirectX 12 or Vulkan API
  • DirectX Raytracing 1.1 API, or higher
  • Visual Studio 2019 or later with Windows 10 SDK version 10.0.20348.0 or later

Known Issues

  • Enabling Vulkan support requires a couple of manual steps, see below
  • SER support on Vulkan is currently work in progress
  • Using SER with DLSS3 Frame Generation is known to cause crashes in certain conditions. We are working on a driver update to address this.
  • Running Vulkan on AMD GPUs may trigger a TDR during TLAS building in scenes with null TLAS instances.

Folder Structure

/bin default folder for binaries and compiled shaders
/build default folder for build files
/donut code for a custom version of the Donut framework
/donut/nvrhi code for the NVRHI rendering API layer (a git submodule)
/external external libraries and SDKs, including NRD, RTXDI, and OMM
/media models, textures, scene files
/tools optional command line tools (denoiser, texture compressor, etc)
/pt_sdk Path Tracing SDK core; Sample.cpp/.h/.hlsl contain entry points
/pt_sdk/PathTracer Core path tracing shaders


At the moment, only Windows builds are supported. We are going to add Linux support in the future.

  1. Clone the repository with all submodules recursively:

    git clone --recursive

  2. Pull the media and other non-git-hosted files:

    cd Path-Tracing-SDK
  3. Create a build folder.

    mkdir build
    cd build

    Any folder name works, but git is configured to ignore folders named build\*

  4. Use CMake to configure the build and generate the project files.

    Use of CMake GUI is recommended but cmake .. works too. Make sure to select the x64 platform for the generator.

  5. Build the solution generated by CMake in the build folder.

    Open the generated solution (i.e. build/PathTracingSDK.sln) with Visual Studio and build it.

  6. Select and run the pt_sdk project. Binaries get built to the bin folder. Media is loaded from media folder.

    If making a binary build, the media and tools folders can be placed into bin and packed up together (i.e. the sample app will search for both media\ and ..\media\).

Building Vulkan

Due to interaction with various included libraries, Vulkan support is not enabled by default and needs a couple of additional tweaks on the user side; please find the recommended steps below:

  • Install Vulkan SDK (we tested with but others will work)
  • Disable STREAMLINE_INTEGRATION (set CMake variable to OFF)
  • Clear CMake cache (if applicable) to make sure the correct dxc.exe path (from Vulkan SDK) is set for SPIRV compilation

User Interface

Once the application is running, most of the SDK features can be accessed via the UI window on the left hand side and drop-down controls in the top-center.


Camera can be moved using W/S/A/D keys and rotated by dragging with the left mouse cursor.

Command Line

  • -scene loads a specific .scene.json file; example: -scene programmer-art.scene.json
  • -width and -height to set the window size; example: -width 3840 -height 2160 -fullscreen
  • -fullscreen to start in full screen mode; example: -width 3840 -height 2160 -fullscreen
  • -adapter to run on a specific GPU in multi GPU environments using a substring match; example: -adapter A3000 will select an adapter with the full name NVIDIA RTX A3000 Laptop GPU
  • -debug to enable the graphics API debug layer or runtime, and the NVRHI validation layer.

Developer Documentation

We are working on more detailed SDK developer documentation - watch this space!


Path Tracing SDK is under active development. Please report any issues directly through GitHub issue tracker, and for any information, suggestions or general requests please feel free to contact us at [email protected]!



Open Source Agenda is not affiliated with "Path Tracing SDK" Project. README Source: NVIDIAGameWorks/Path-Tracing-SDK
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