Silk Brush README

Silk Brush is a port of Tilt Brush to WebXR.

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Tilt Brush is licensed under Apache 2.0. It is not an officially supported Google product. See the LICENSE file for more details.

Trademarks

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.

Building the application

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

Prerequisites

• Unity 2019.4.18f1
• Python 2.7.0 (Optional — needed only if you wish to run the scripts in the Support/bin directory)

Changing the application name

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. Before building the application, go into App.cs and the Player settings to change the company and application names to your own.

Please see the Tilt Brush Brand Guidelines for more details.

Additional features

You should be able to get the basic version of Tilt 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
• *.fbx file support
• Camera path support
• Video recording for the camera
• Offline rendering support
• GIF support for the camera

Note: Uploading to Poly has been removed completely and cannot be added back in, because it uses an internal Google API. Download from Poly can still be enabled.

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 underscorediscovery.

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
   • Poly API — for accessing the Poly model library
   • 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 Other. 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. There is an asset in the Assets/ directory called Secrets that contains a Secrets field. Add a new item to this field.
2. Select Google as the service. Paste in the API key, client ID, and client secret that were generated earlier.

Tilt Brush intro sketch

The Tilt 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 Tilt Brush in the Unity Editor.
2. Select Tilt > 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 Tilt > 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 Tilt Brush.

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.
2. Add the client ID and secret to the Secrets file.
3. Set the service as Sketchfab. Leave the API key blank.

FBX file support

You will need to build C# wrappers for the Autodesk FBX (the Autodesk filebox format) SDK in order to import or export FBX and OBJ files in the app. See Support/fbx/README.md for details.

Camera path support

Follow these steps to enable camera path support:

1. Enable video support.
2. Uncomment the code in CameraPathCaptureRig.RecordPath().

Video support

To get video support you will need to put an ffmpeg.exe binary in to /Support/ThirdParty/ffmpeg/bin. We have created a script to build one for you - it temporarily requires around 2GB of space to build but will clear up after itself.

Follow these steps to get video support:

1. Find '/Support/ThirdParty/ffmpeg/BuildFfmpeg.ps1', right-click on it in explorer and select 'Run with Powershell'. It will take some time to build.
2. In Unity, modify /Assets/PlatformConfigPC and add 'Video' to 'Enabled Multicam Styles'. 'Snapshot' should always be enabled.

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 Tilt Brush, a .bat file is generated next to the .mp4 for offline rendering support. This .bat file requires the path to the executable of Tilt 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.

GIF support

GIF support was removed for licensing reasons. To get GIF support, integrate your own system by following these steps:

1. Add the encoding code in around lines 129 - 148 of Assets/Scripts/Gif Creation/GifEncodeTask.cs.
2. Modify Assets/PlatformConfigPC and Assets/PlatformConfigMobile. Add Auto GIF and/or Time GIF to Enabled Multicam Styles.

The released PC build had the following settings:

• Snapshot
• Auto GIF
• Time GIF
• Video

The released Quest build had the following settings:

• Snapshot
• Time GIF

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.

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 Poly or Sketchfab, and may break if loaded into production versions of Tilt Brush.

Turning on experimental mode

Follow these steps to turn on experimental mode:

1. Find the Config object in the main scene by going to App > Config.
2. Turn on the Is Experimental flag.

The Tilt Brush build system will then set up the experimental flag as needed when you make a build.

Making your code experimental

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

# if (UNITY_EDITOR || EXPERIMENTAL_ENABLED)

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

# endif

In the editor, all you need to enable experimental mode is to turn on the experimental flag. The EXPERIMENTAL_ENABLED scripting definition needs to be set, or the code will not be compiled into the build at all. This prevents unfinished features from being accessed by people who hack or decompile the executable.

Experimental brushes

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