Open Brush - Art From All Angles

Open Brush is a free fork of Tilt Brush, a room-scale 3D-painting virtual-reality application available from Google, originally developed by Skillman & Hackett. We have made a large number of changes from the original repository, including Unity upgrades and feature additions to bring Open Brush up to modern XR development standards. You can find the notable changes on our docs site.

We hope to maintain and improve upon Tilt Brush as a community-led project, free forever!

As the original repo is archived we cannot submit PRs, so feel free to submit them here!

User Guide
Developer Notes
Roadmap
Please join the Icosa Discord and get involved!
List of tutorials, write-ups and other things from the community
Support us on Open Collective

Downloads

Stores

• SideQuest
• Meta Horizon (Quest)
• Steam
• Oculus Rift
• Viveport Desktop
• Pico
• itch.io

GitHub

• Formal GitHub Releases
• Bleeding Edge GitHub Releases

Acknowledgements

• Thank you to the Tilt Brush developers for your amazing work and for finding a way to open source the app!
• SiMonk0 for the great new logo!
• The SideQuest team for your support.
• VR Rosie for promotional artwork, banners, and videos.

Bleeding Edge Releases

Instead of waiting for a formal release, you can download a ZIP from Github containing an automatically built release for either Windows (SteamVR) or Oculus Quest / Quest 2 from the Github releases page. Versions of the form "vX.Y.0" are official releases, whereas versions that do not end in .0 are made available for testing purposes only, with no guarantees as to their quality. Additionally, these releases are marked as "pre-release". However, if you'd like to test a recent change prior to the official release, you can use these either in place of or in parallel with the formal Open Brush releases.

These builds share a save location with the official Open Brush release, but can be installed alongside the formal version. The Oculus build, like all sideloaded content, will be listed in "Unknown Sources", and will have the word "Github" appended to the name (with a different package name as well) to differentiate it from the official release).

Note that the "experimental" builds contain experimental brushes, and sketches created using the experimental brushes may appear differently when loaded in the official build of Open Brush!

In addition, there is also a version created for Windows Monoscopic that is listed as an "Artifact" of the Github Actions, however, this is intended only for developers, and should not be used by general users. You can find it by browsing to the commit list, and then clicking on the green check mark below the title (next to the XXX committed XXX ago), and scroll to the build you want, and click on Details. Then, towards the upper right corner, click on Artifacts and click on the name of the build. Unzip the downloaded file, and either run the executable (Desktop OpenXR/Monoscopic) or install the apk (Android Oculus) using adb install com.Icosa.OpenBrush-github.apk.

Important note from the original Tilt Brush README

The Tilt Brush trademark and logo (“Tilt Brush Trademarks”) are trademarks of Google, and are treated separately from the copyright or patent license grants contained in the Apache-licensed Tilt Brush repositories on GitHub. Any use of the Tilt Brush Trademarks other than those permitted in these guidelines must be approved in advance.

For more information, read the Tilt Brush Brand Guidelines.

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Building the application

Get the Open Brush open-source application running on your own devices.

Prerequisites

• Unity 2022.3.34f1
• Python 3 (Optional — needed only if you wish to run the scripts in the Support/bin directory) Tested with Python 3.8.

Running the application in the Unity editor

Follow these steps when running the application for the first time:

1. Start Unity.
2. Go to File > Open Scene. \
3. Select /Assets/Scenes/Main.unity. Unity should automatically prompt you to import TextMesh Pro.
4. Choose Import TMP Essentials.
   You can also do this through Window > TextMesh Pro > Import TMP Essential Resources.
5. Press Play.

These steps have been tested with Release 1.0.54.

Building the application from the Unity editor

Although it's possible to build Open Brush using the standard Unity build tools, we recommend using a build script to ensure the application builds with the correct settings. To run this script, go to Open Brush > Build > Do Build, or build from the Open Brush build window by navigating to Open Brush > Build > Build Window.

Note: The application may take a while to build the first time.

Building the application from the Windows command line

Use the build script in the Support/bin directory to specify the target platform and the build options you wish to enable. Run build —help to see the various build options.

Additional features

You should be able to get the basic version of Open Brush up and running very quickly. The following features will take a little more time.

• Google service API support
• Enabling native Oculus support
• Sketchfab support
• Offline rendering support

Systems that were replaced or removed when open-sourcing Tilt Brush

Some systems in Tilt Brush were removed or replaced with alternatives due to open-source licensing issues. These are:

• Sonic Ether Natural Bloom. The official Tilt Brush app uses a version purchased from the Asset Store; the open-source version uses Sonic Ether's slightly modified open-source version.
• FXAA. The official Tilt Brush app uses a modified version of the FXAA that Unity previously released with the standard assets on earlier versions of Unity - FXAA3 Console. This has been replaced with FXAA by jintiao.
• Vignette and Chromatic Aberration. The official Tilt Brush app uses modified versions of the Vignette and Chromatic Aberration effects that came with the standard assets in earlier versions of Unity. These have been replaced with a modified version of KinoVignette by Keijiro.
• Tilt Shift. The official Tilt Brush app uses modified versions of the Tilt Shift effect that came with the standard assets in earlier versions of Unity. These have been replaced with a modified version of Tilt shift by ruby0x1.

Generating Secrets file

Credentials for services such as Google and Sketchfab are stored in a SecretsConfig scriptable object. This has been ignored in the git config for safety. To add it back:

1. Right click in the root /Assets folder in Unity's project window. Select Create, then Secrets Config. This will create Secrets.asset in the Asset folder.
2. In Scenes/Main.unity go to App > Config and replace SecretsExample with the newly generated Secrets.asset.

Google service API support

Set up Google API support to access Google services in the app.

Enabling Google service APIs

Follow these steps when enabling Google service APIs:

1. Create a new project in the Google Cloud Console.

2. Enable the following APIs and services:

   • YouTube Data API v3 — for uploading videos to YouTube
   • Google Drive API — for backup to Google Drive
   • People API — for username and profile picture

Note: The name of your application on the developer console should match the name you've given the app in App.kGoogleServicesAppName in App.cs.

Creating a Google API key

Follow these steps when creating a Google API key:

1. Go to the Credentials page from the Google Cloud Console.
2. Click Create Credential and select API key from the drop-down menu.

Google OAuth consent screen information

The OAuth consent screen asks users for permission to access their Google account. You should be able to configure it from the Credentials screen.

Follow these steps when configuring the OAuth consent screen:

1. Fill in the name and logo of your app, as well as the scope of the user data that the app will access.

2. Add the following paths to the list of scopes:

   • Google Drive API ../auth/drive.appdata
   • Google Drive API ../auth/drive.file

Creating an OAuth credential

The credential identifies the application to the Google servers. Follow these steps to create an OAuth credential:

1. Create a new credential on the Credentials screen.
2. Select OAuth, and then select Desktop App. Take note of the client ID and client secret values that are created for you. Keep the client secret a secret!

Storing the Google API Key and credential data

Follow these steps to store the Google API Key and credential data:

1. Follow the steps to create your secrets file. Add a new item to the Secrets field.
2. Select Google as the service. Paste in the API key, client ID, and client secret that were generated earlier.

Enabling native Oculus support

Open Brush targets OpenXR instead of Oculus by default. Follow these steps to enable native Oculus support: .

1. In the Standalone and Android tabs of the Player settings, go to Other Settings > Scripting Define Symbols.
2. Click the + button to create a new entry.
3. Add OCULUS_SUPPORTED and press Apply.

Building your app for Oculus Quest

Follow these steps to build your app for Oculus Quest:

1. Set up your machine for Oculus Quest Development.
2. Make sure the following are set in Unity:
   • Open Brush > Build > Plugin: Oculus
   • Open Brush > Build > Platform: Android
   • Open Brush > Build > Runtime: IL2CPP
3. Navigate to Open Brush > Build > Do Build.
4. Find the generated executable. It will most likely be somewhere under ../Builds/OculusMobile_Release_OpenBrush/.
5. Run adb install com.Icosa.OpenBrush.apk.

Publishing to Oculus stores

Note: Tilt Brush is a Google trademark. If you intend to publish a cloned version of the application, you are required to choose a different name to distinguish it from the official version.

Follow these steps to publish to Oculus stores:

1. Get an application ID from Oculus. The desktop and quest versions of each application need separate IDs.
2. Follow the steps to create your secrets file. Add 2 new items to the Secrets field.
3. Add these IDs to the Secrets file. Both Oculus and OculusMobile should have their own entries.
4. Put the app IDs in the Client ID field for each.

Open Brush intro sketch

The Open Brush intro sketch uses some slightly modified shaders to produce the animating-in effect while the sketch fades in. For faster loading, the intro sketch is turned into a *.prefab file beforehand. Only the shaders used in the intro sketch have been converted to work with the introduction.

• The current intro sketches are located in Support/Sketches/Intro. There are two versions, one for PC and one for mobile.
• The *.prefab files are located in Assets/Prefabs/Intro.
• The materials and shaders used in the intro are located in Assets/Materials/IntroMaterials.
• The Assets/PlatformConfigPC and Assets/PlatformConfigMobile files reference the *.prefab files that will be used in the intro.

Creating an intro sketch

Follow these steps to replace or alter the intro sketch:

1. Make sure the sketch of your choice is already loaded. Run Open Brush in the Unity Editor.
2. Select Open Brush > Convert To Intro Materials in the main Unity menu. This converts the materials in the sketch to the intro versions.
   You will get warnings in the console for any materials it could not convert, as well as a summary of how many materials it converted.
3. Navigate the hierarchy. Under the Main scene, open SceneParent/Main Canvas. Select any of the Batch_... objects to check whether they have the intro materials set.
4. Move any objects that do not start with Batch_ out from under the Main Canvas node.
5. Select the Main Canvas node and run the Open Brush > Save Game Object As Prefab menu command.
   The scene will be saved as a *.prefab file called gameobject_to_prefab. under the Assets/TestData folder.
6. Move the game object into the Assets/Prefabs/Intro folder.
7. Update the references in Assets/PlatformConfigPC and Assets/PlatformConfigMobile to point to your new prefab file.

Creating an intro sketch for mobile applications

You may want to have a pared-down version of the intro sketch for the mobile version of the app. Stroke simplification is located in the Settings menu inside Open Brush.

New Scenes

By default, your app will only build the scenes defined in the DoBuild method (string[] scenes = {...} ) in BuildTiltBrush.cs under Assets/Editor/. Make sure to add your custom scenes to this array if you want to see them in app.

Sketchfab support

Follow these steps to enable Sketchfab support:

1. Contact Sketchfab for a client ID and secret before you can upload to their service.

   • The Application Name will probably need to be changed
   • The Grant Type should be Authorization Code
   • The URI should be http://localhost:40074/sketchfab

2. Follow the steps to create your secrets file. Add a new item to the Secrets field.

3. Add the client ID and secret to the field.

4. Set the service as Sketchfab. Leave the API key blank.

Video support bug fix

If you add video support, you may encounter a bug where the "Looking for audio" and "Play some music on your computer" text will disappear if the controller is angled too far. Fix this by doing the following:

1. In Unity, find the /Assets/TextMesh Pro/Resources/Shaders/TMP_SDF.shader file.
2. Duplicate it and rename this file TMP_SDF-WriteDepth.shader.
3. Open the new file in a code or text editor and make the following changes to it:
   1. Change the name from TextMeshPro/Distance Field to TextMeshPro/Distance Field Depth.
   2. Change Zwrite Off to Zwrite On.
4. In Unity, select /Assets/Fonts/Oswald-Light SDF.asset.
5. Under Atlas & Material, double click Oswald-Light SDF Material.
6. At the top, change the name for Shader from TextMeshPro/Distance Field to TextMeshPro/Distance Field Depth.

Offline rendering support

When the user records a video from a saved sketch in Open Brush, a .bat file is generated next to the .mp4 for offline rendering support. This .bat file requires the path to the executable of Open Brush. The code for writing out this path to the file has been removed.

Follow these steps to restore the path:

1. Open the file Assets/Scripts/Rendering/VideoRecorderUtils.cs in a code or text editor.
2. Look for the function CreateOfflineRenderBatchFile near the bottom of the file.
3. In the function, find the comments on how to modify the string to point to the executable path.
4. Update the string to point to the correct path.

Experimental mode

Experimental mode is where features live before they are ready to be released in a production build. This mode enables the experimental brushes and experimental panel while disabling the intro sequence. Experimental mode can be enabled from the settings panel, and requires a restart.

New features and brushes that you find in experimental mode may not work as expected. Sketches that use experimental features and brushes won't work on Icosa or Sketchfab, and may break if loaded into production versions of Open Brush.

Making your code experimental

Code in experimental mode is usually surrounded by the following block:

    if (Config.IsExperimental) {
      // Experimental code goes here
    }

Experimental brushes

Experimental brushes and environments are located in the Assets/Resources/X folder. They are not visible in non-experimental mode.