RTXDI SDK and Sample Applications

Version 2.3.0.

Change Log

Introduction

RTX Dynamic Illumination is a framework that originally facilitated implementation of efficient direct light sampling in real-time renderers. It is based on the ReSTIR algorithm published in the paper called "Spatiotemporal reservoir resampling for real-time ray tracing with dynamic direct lighting" by B. Bitterli et al.

Starting with version 2.0, RTXDI also includes ReSTIR GI functionality, which allows applications to apply importance resampling to indirect illumination rendered using path tracing. For more information about the indirect illumination algorithm, see the paper called "ReSTIR GI: Path Resampling for Real-Time Path Tracing" by Y. Ouyang et al. The feature is described in more detail in this document.

For more information about RTXDI, see the NVIDIA Developer Page.

Package Contents

Libraries/Rtxdi is a submodule that contains the integrable runtime sources that are meant to be included in the application build:

• Rtxdi/Include/Rtxdi has the include files, both for host code and for shaders.
• Rtxdi/Include/Rtxdi/DI/ and Rtxdi/Include/Rtxdi/GI/ are the main shader include folders that contain the resampling implementations for their respective algorithms.
• Rtxdi/Source has the host code with various utility functions for setting up the parameters and resources for resampling.

Samples contains two sample projects, MinimalSample and FullSample. The MinimalSample/Source project implements ReSTIR DI in a single combined pass to show a minimum viable implementation. The FullSample/Source project implements ReSTIR DI in several passes integrated into a broader rendering pipeline to show a more standard implementation. The shaders for each project live in their respective MinimalSample/Shaders and FullSample/Shaders folders.

External contains project dependencies both from Nvidia and third parties:

• External/donut is a Git submodule structure with the "Donut" rendering framework used to build the sample apps.

• External/NRD is a Git submodule with the "NRD" denoiser library.

• External/DLSS is a Git submodule with the Deep Learning Super-Sampling SDK.

• External/dxc is a recent version of DirectX Shader Compiler. However, unlike the other dependencies, it is not a Git submodule but is instead fetched by CMake at project configuration time.

Assets/Media is a Git submodule containing the RTXDI SDK Sample Assets.

Building and Running the Sample Apps

Note that because the rtxdi-assets submodule that is cloned into Assets/Media uses LFS, cloning it without LFS installed will result in files containing LFS pointers instead of the actual assets.

Windows

1. Install LFS support by following the instructions on git-lfs.com

2. Clone the repository with all submodules:

   • git clone --recursive https://github.com/NVIDIAGameWorks/RTXDI.git

   If the clone was made non-recursively and the submodules are missing, clone them separately:

   • git submodule update --init --recursive

3. Configure the solution with CMake. The easiest option is to use CMake GUI.

4. Assuming that the RTXDI SDK tree is located in D:\RTXDI, set the following parameters in the GUI:

   • "Where is the source code" to D:\RTXDI
   • "Where to build the binaries" to D:\RTXDI\build

5. Click "Configure", set "Generator" to the Visual Studio you're using (tested with VS 2019 version 16.8.2), set "Optional platform" to x64, click "Finish".

6. Click "Generate", then "Open Project".

7. Build the solution with Visual Studio

8. Run the FullSample or MinimalSample projects.

Linux

1. Make sure the necessary build packages are installed on the target system. For Ubuntu 20.04 (amd64), the following command is sufficient:

   • sudo apt install build-essential cmake xorg-dev libtinfo5

2. Install LFS support by following the instructions on git-lfs.com. Note that on Ubunutu 21.04+ you can simply:

   • sudo apt install git-lfs

3. Clone the repository with all submodules:

   • git clone --recursive https://github.com/NVIDIAGameWorks/RTXDI.git

   If the clone was made non-recursively and the submodules are missing, clone them separately:

   • git submodule update --init --recursive

4. Create a build folder:

   • mkdir build && cd build

5. Configure the project with CMake:

   • cmake ..

6. Build:

   • make -j8 (example for an 8-core CPU, or use Ninja instead)

7. Run:

   • bin/FullSample or bin/MinimalSample

Vulkan support

The RTXDI sample applications can run using D3D12 or Vulkan, which is achieved through the NVRHI rendering API abstraction layer and HLSL shader compilation to SPIR-V through DXC (DirectX Shader Compiler). We deliver a compatible version of DXC through packman. If you wish to use a different (e.g. newer) version of DXC, it can be obtained from Microsoft/DirectXShaderCompiler on GitHub. The path to a custom version of DXC can be configured using the DXC_PATH and DXC_SPIRV_PATH CMake variables.

By default, the sample apps will run using D3D12 on Windows. To start them in Vulkan mode, add --vk to the command line. To compile the sample apps without Vulkan support, set the CMake variable DONUT_WITH_VULKAN to OFF and re-generate the project.

To enable SPIV-V compileation tests, set the GLSLANG_PATH variable in CMake to the path to glslangValidator.exe in your Vulkan installation.

Integration

See the Integration Guide.