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Open Shading Language Reel 2020

Build Status License CII Best Practices Documentation Status

Introduction

Welcome to Open Shading Language!

Open Shading Language (OSL) is a small but rich language for programmable shading in advanced renderers and other applications, ideal for describing materials, lights, displacement, and pattern generation.

OSL was originally developed by Sony Pictures Imageworks for use in its in- house renderer used for feature film animation and visual effects, released as open source so it could be used by other visual effects and animation studios and rendering software vendors. Now it's the de facto standard shading language for VFX and animated features, used across the industry in many commercial and studio- proprietary renderers. Because of this, the work on OSL received an Academy Award for Technical Achievement in 2017.

OSL is robust and production-proven, and has been used in films as diverse as "The Amazing Spider-Man," "Hotel Transylvania," "Edge of Tomorrow", "Ant Man", "Finding Dory," and many more. OSL support is in most leading renderers used for high-end VFX and animation work. For a full list of films and products, see the filmography.

The OSL code is distributed under the "New/3-clause BSD" license, and the documentation under the Creative Commons Attribution 4.0 International License. In short, you are free to use OSL in your own applications, whether they are free or commercial, open or proprietary, as well as to modify the OSL code and documentation as you desire, provided that you retain the original copyright notices as described in the license.

How OSL is different

OSL has syntax similar to C, as well as other shading languages. However, it is specifically designed for advanced rendering algorithms and has features such as radiance closures, BSDFs, and deferred ray tracing as first-class concepts.

OSL has several unique characteristics not found in other shading languages (certainly not all together). Here are some things you will find are different in OSL compared to other languages:

What OSL consists of

The OSL open source distribution consists of the following components:

Where OSL has been used

This list only contains films or products whose OSL use is stated or can be inferred from public sources, or that we've been told is ok to list here. If an OSL-using project is missing and it's not a secret, just email the OSL project leader or submit a PR with edits to this file.

Renderers and other production tools with OSL support

(In approximate order of adding OSL support)

Significant work using OSL, grouped by year of release date:

(Here we are considering "significant work" to mean a feature film released theatrically or on a major streaming platform, TV/streaming series heavily featuring visual effects or animation, or short films that have won or been nominated for major awards.)

Building and Installation

Please read the INSTALL.md file for detailed instructions on how to build and install OSL.

Documentation

The OSL language specification can be found at src/doc/osl-languagespec.pdf (in a source distribution) or in the share/doc/OSL/osl-languagespec.pdf file of an installed binary distribution.

Experimental OSL Documentation on ReadTheDocs This will be the future documentation. It's probably as complete as the PDF, but it needs some proofreading, so the PDF is still considered the authoritative source for now. But some time soon, the old PDF specification will be deprecated in favor of this online documentation.

<!-- is the best place to start if you are interested in how to use OSL, its APIs. -->

There is also a PDF version.

For those interested in learning to program shaders in OSL, there is the Siggraph 2022 Educator's Forum OSL Shaders for RenderMan course, which uses RenderMan in the examples and Supplementary Materials, but which is primarily about shader writing in OSL.

Contact & reporting problems

Simple "how do I...", "I'm having trouble", or "is this a bug" questions are best asked on the osl-dev developer mail list. That's where the most people will see it and potentially be able to answer your question quickly (more so than a GH "issue").

Bugs, build problems, and discovered vulnerabilities that you are relatively certain is a legit problem in the code, and for which you can give clear instructions for how to reproduce, should be reported as issues.

If you think you've found a potential vulnerability in OSL, please confidentially report it by emailing the project administrators at security@openshadinglanguage.org.

If any other issue requires confidentiality that precludes a public question or issue, you may contact the project administrator privately at lg@larrygritz.com.

Contributing

OSL welcomes code contributions, and nearly 50 people have done so over the years. We take code contributions via the usual GitHub pull request (PR) mechanism. Please see CONTRIBUTING for detailed instructions.

Contacts, Links, and References

OSL GitHub page

Read or subscribe to the OSL development mail list

Most recent PDF of the OSL language specification

OSL home page

Credits

The current project leadership is documented in the Governance file.

Many people have contributed features, bug fixes, and other changes to OSL over the years: Steve Agland, Shane Ambler, Martijn Berger, Farchad Bidgolirad, Nicholas Bishop, Curtis Black, Rasmus Bonnedal, Solomon Boulos, Stefan Bruens, Stefan Büttner, Matthaus G. Chajdas, Clark Chen, Mehdi Chinoune, Alejandro Conty, Damien Courtois, Dieter De Baets, Thomas Dinges, Daniel Dresser, Mads Drøschler, Peter Ellerington, Luke Emrose, Louis Feng, Mark Final, Henri Fousse, Stephen Friedman, Syoyo Fujita, Tim Grant, Larry Gritz, Nicolas Guiard, Euan Haahr, Derek Haase, Sven-Hendrik Haase, John Haddon, Niklas Harrysson, Daniel Heckenberg, Chris Hellmuth, Adrien Herubel, Dan Horák, Thiago Ize, Matt Johnson, Ronan Keryell, Chris Kulla, Elvic Liang, Max Liani, Adam Martinez, John Mertic, Bastien Montagne, Steena Monteiro, Patrick Mours, Alexis Oblet, Erich Ocean, Mikko Ohtamaa, Jino Park, Alexei Pawlow, Mitch Prater, Jay Reynolds, Declan Russell, Benoit Ruiz, Patrick Scheibe, Alex Schworer, Jonathan Scruggs, Sergey Sharybin, Mark Sisson, Sandip Shukla, Cliff Stein, Stephan Steinbach, Luya Tshimbalanga, Esteban Tovagliari, Brecht Van Lommel, Thibault Vergne, Alexander von Knorring, Aidan Welch, Alex Wells, Roman Zulak. (Listed alphabetically; if we've left anybody out, it is inadvertent, please let us know.)

We cannot possibly express sufficient gratitude to the managers at Sony Pictures Imageworks who allowed this project to proceed, supported it wholeheartedly, and permitted us to release the source, especially Rob Bredow, Brian Keeney, Barbara Ford, Rene Limberger, Erik Strauss, and Mike Ford.

Huge thanks also go to the crack shading team at SPI, and the brave lookdev TDs and CG supes willing to use OSL on their shows. They served as our guinea pigs, inspiration, testers, and a fantastic source of feedback. And of course, the many engineers, TDs, and artists elsewhere who incorporated OSL into their products and pipelines, especially the early risk-takers at Chaos Group, Double Negative, Pixar, DNA, Isotropix, and Animal Logic. Thank you, and we hope we've been responsive to your needs.

OSL was not developed in isolation. We owe a debt to the individuals and studios who patiently read early drafts of the language specification and gave us very helpful feedback and additional ideas, as well as to the continuing contributions and feedback of its current developers and users at other VFX and animation studios.

The OSL implementation depends upon several other open source packages, all with compatible licenses:

OSL's documentation incorporates parts of Markdeep (c) 2015-2016, Morgan McGuire, and highlight.js (c) 2006, Ivan Sagalaev, both distributed under BSD licenses.