Getting Started with RTX Ray Tracing

This directory contains Chris Wyman's shader tutorials from the GDC 2019 and SIGGRAPH 2018 courses "Introduction to DirectX Raytracing". Visit the SIGGRAPH course webpage to get more details, more descriptive code walkthroughs, some prebuilt tutorial binaries, course presentations, and other information about the course.

Please read this document carefully before trying to build our tutorials. Given DirectX Raytracing is new, building code that relies on it can easily break in surprising ways if you do not have the latest requirements. We have tried to specify all requirements and caveats, to avoid pain in getting started, and we will update this tutorial code as requirements change. Please contact us or log an issue if you run into unexpected troubles not covered below.

Also note: None of the tutorial examples are intended to demonstrate best practices for highly optimized performance. These samples are optimized to provide an easy starting point, clarity, and general code readability (rather than performance).

Source code for our tutorials and shaders is licensed under a BSD license. Models, textures, and other resources have their own licenses (see 'Acknowledgments' below).

Software/Hardware Requirements:

0. This code.
   • If you clone this repository using a command window, please use the standard Windows CMD window, not a Linux shell, which can alter the CR/LF in project files and make them fail with errors such as "c1xx : fatal error C1083: Cannot open source file: '..\SharedUtils\FullscreenLaunch.cpp': No such file or directory" and similar when building the code.
1. Windows 10 RS5.
   • If you run "winver.exe" you should see Version 1809 (OS Build 17763) or later.
   • See older versions of this repository for unsupported code that runs on RS4 (v1803).
2. Microsoft Visual Studio 2017.
   • The free Community Edition works fine.
3. Windows 10 SDK 10.0.17763.0 (aka Windows 10 SDK, version 1809).
   • Download SDK
   • Note: Later SDK versions probably work, but you need to change each Visual Studio project to look for the SDK you download, rather than 10.0.17763.0.
4. A graphics card supporting DirectX Raytracing.
   • Currently, limited to newer NVIDIA cards, e.g., Titan V and Turing-class cards.
5. An NVIDIA driver that natively supports DirectX Raytracing.
   • Includes most public drivers version 400 or later.
   • We recommend updating to recent drivers to provide highest performance and stability when ray tracing.
6. Make sure you get Falcor from (https://github.com/NVIDIAGameWorks/Falcor) and checkout the commit tagged v3.1 (commit 5a12f298c15b82297447906afafdcf5a2f58f99e).
   • The repo should be setup with a submodule to do this automatically.
   • This version of Falcor should reside in the Falcor/ subdirectory of the GettingStartedWithRTXRayTracing repository.
   • If compiling gives a bunch of undefined references and cast conversion errors, you have the wrong version of Falcor.
   • We plan to update these tutorials once more for Falcor 4.0, perhaps including as part of the distribution.
7. Make sure to build a "ReleaseD3D12" (or "DebugD3D12") version of the samples.

Getting started:

Satisfying the requirements above, you're ready to get started.

You should be able to install the tutorials directory almost anywhere. However, we have run into problems with the build scripts if the install directory contains spaces. For now, we suggest avoiding that.

Before compiling, you need to include Falcor and download Falcor dependencies. Falcor itself is downloaded by the link on the Github page for these Getting Started program, which currently leads to this Falcor 3.1 repo. If not done automatically, download and put these files in the Falcor/ directory.

Next, run update_dependencies.bat in the Falcor/ directory. It should download a bunch of packages and put them in Falcor/Framework/Externals/ and Falcor/Media/. The Visual Studio solution will call this script for you via a pre-build step, but it sometimes gives confusing error messages when starting a parallel build. This is not a problem if you run the script manually.

Now open the Visual Studio solution GettingStartedWithRTXRayTracing.sln. We suggest you initially choose the "ReleaseD3D12" configuration to begin, as programs will start up and run faster. Then "Build | Build Solution" to build all the tutorial programs. In the Solution Explorer you right-click and choose "Set as StartUp Project" to run that tutorial.

Most tutorials load a default scene (the "modern living room" from Benedikt Bitterli's page). We also include one other simple scene in directory Falcor/Media/Arcade/. Additional, more complex scenes can be downloaded from the Open Research Content Archive:

• Amazon Lumberyard Bistro
• NVIDIA Emerald Square City Scene
• UE4 Sun Temple

Troubleshooting:

Visual Studio gives "Error MSB3073" when building. This is an issue with the pre-build step, and we've seen it in the following cases:

• The installation directory name (or parent directories) contains a space.
• You ran a parallel build; our pre-build script gets called for each tutorial and fails on all except the first. This is usually a one-time error and rebuilding solves the problem.
• There are installation problems with the dependencies. Remove the "Falcor/Media/" directory and all subdirectories in the Falcor/Framework/Externals/ directory (you can do this with delete_dependencies.bat) and rerun update_dependencies.bat in the Falcor/ directory.

Visual Studio gives "c1xx : fatal error C1083: Cannot open source file: '..\SharedUtils\FullscreenLaunch.cpp': No such file or directory" or similar when building. As noted in step 0, cloning the repository with Git under certain shells such as Ubuntu can cause problems with end of line characters and so alter project files. Use the Windows CMD command prompt, or if all else fails, download the zip.

Tutorial Information:

Note the UI has a number of slightly-hidden features. Hover your mouse over the "(?)" next to "Keyboard Shortcuts" at the top of the menu on the left to see some useful key shortcuts. "Global Controls" can be viewed by clicking on the small arrow to the left of this text.

The mouse orbits and WASD moves the camera through the scene, along with Q and E for down and up. Camera movement can be made slower by holding down "Ctrl" and faster by holding down "Shift."

Each tutorial demonstrates how to implement some basic rendering algorithm. Much of the focus of each is the set of shaders in the Shaders directory. You are encouraged to modify these shaders and the rest of the code as you wish. One nice feature of the Falcor framework is that you can modify and reload the shaders without restarting the program. While focused on the program, press F5 and then change the view or toggle some feature that causes a refresh. The new shaders should then take effect.

Additional Resources for DirectX Raytracing:

Chris has a code walkthrough for his shader tutorials. You can download most of the prebuilt binaries (please read the readme to avoid issues; also, does not include the Sphereflake demo).

Other useful resources:

• The DirectX Raytracing (DXR) specification v0.09.
• Microsoft's experimental installation package with everything needed to build DXR apps.
• Microsoft's early DXR samples.
• NVIDIA's early DXR samples.
• NVIDIA Research's Falcor prototyping framework.
• The Real-Time Rendering Ray Tracing Resources Page, which includes a free chapter on the basic ideas behind DXR and interactive ray tracing.

Acknowledgments:

The desert HDR environment map (MonValley Dirtroad) is provided from the sIBL Archive under a Creative Commons license CC BY-NC-SA 3.0 US.

The included "pink_room" scene is named 'The Modern Living Room' by Wig42 on Benedikt Bitterli's webpage. It has been modified to match the Falcor material system. This scene was released under a CC-BY license. It may be copied, modified and used commercially without permission, as long as: Appropriate credit is given to the original author The original scene file may be obtained here.

The moon texture came from here under CC BY 4.0 license.

The earth texture is public domain from here.

The normal map texture is licensed CC0 from here.