PTheMagician / RTXDI

RTXDI SDK and Sample App

Version 1.3.0.

Change Log

Introduction

RTX Direct Illumination is a framework that facilitates the implementations 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.

For more information, see the NVIDIA Developer Page.

Package Contents

rtxdi-sdk contains the SDK source code files that are meant to be included into the application build:

• rtxdi-sdk/include has the include files, both for host code and for shaders
• rtxdi-sdk/include/rtxdi/ResamplingFunctions.hlsli is the main shader include file that contains the resampling implementation
• rtxdi-sdk/shaders has the shader files that are supposed to be compiled through whatever means the application normally uses
• rtxdi-sdk/src has the host code with various utility functions for setting up the parameters and resources for resampling

src contains the sample application host code.

shaders contains the sample application shaders.

donut is a submodule structure with the "Donut" rendering framework used to build the sample app.

NRD is a submodule with the "NRD" denoiser library.

DLSS is a submodule with the Deep Learning Super-Sampling SDK.

RTXGI is a submodule with the RTX Global Illumination SDK.

Additional contents delivered through packman:

dxc is a recent version of DirectX Shader Compiler;

media contains the media files necessary for the sample app to run.

NOTE: the NRD, DLSS and RTXGI dependencies are optional. If you cannot access any of these repositories, just skip cloning the submodule(s). Git doesn't make that easy, but initializing submodules individually should work, like so:

git submodule update --init --recursive donut DLSS

Building and Running the Sample App

Windows

1. Clone the repository with all submodules (see the note about optional submodules above):

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

2. Pull the media files and DXC binaries from packman:

   • update_dependencies.bat

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 rtxdi-sample project.

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. Clone the repository with all submodules (see the note about optional submodules above):

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

3. Pull the media files and DXC binaries from packman:

   • cd RTXDI && ./update_dependencies.sh

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/rtxdi-sample

Vulkan support

The RTXDI sample application 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_DXIL_EXECUTABLE and DXC_SPIRV_EXECUTABLE CMake variables.

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

Integration

See the Integration Guide.