Tips And Configurations

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Advanced Configuration

Advanced configurations allow you to customize LIV SDK behavior to fit your project’s unique requirements. These configurations optimize capture methods, enable advanced rendering features, and address specific use cases like transparency and global clipping planes.

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Capture Methods

The LIV SDK offers multiple capture methods to balance performance, transparency support, and post-processing effects. Selecting the correct method depends on the requirements of your project. How to Configure:

1. Go to Edit > Project Settings > Plugins > LIV.
2. Select the method appropriate to your project requirements:
   • Use LivCaptureSingle for maximum performance.
   • Use LivCaptureGlobalClipPlaneNoPostProcess or LivCaptureGlobalClipPlanePostProcessfor transparency.

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Enable Transparency

Context: Transparency is crucial for rendering translucent objects like glass, holograms, and effects. To display transparency correctly, specific capture methods and material settings must be configured. Steps to Enable Transparency:

1. Use one of these supported capture methods:
   • LivCaptureGlobalClipPlaneNoPostProcess
   • LivCaptureGlobalClipPlanePostProcess

Common Issues - Transparency Not Rendering:

• Ensure the material Blend Mode is set to Translucent (see Material Configuration).
• Confirm that Global Clip Plane is enabled.

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Global Clip Plane

Context The Global Clip Plane is essential for splitting the MR capture into separate layers (foreground, background, player). Without it, occlusion will fail, and players or objects may render incorrectly above everything else. Steps to Enable Global Clip Plane:

1. Navigate to Edit > Project Settings > Engine > Rendering > Reflections.
2. Enable Support Global Clip Plane.
3. Restart the editor to apply the settings.

Use Case - Required for:

• LivCaptureGlobalClipPlaneNoPostProcess
• LivCaptureGlobalClipPlanePostProcess
• Scenes with foreground transparency requiring correct occlusion.

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Material Configuration for Additive Transparency

Context: Materials using Additive Blend Mode skip depth testing, causing them to always render in front of other objects. This disrupts occlusion and breaks MR layering in LIV. Steps to Fix Additive Materials:

1. Open the Material Editor for the problematic object.
2. In the Details Panel:
   • Change Blend Mode to Translucent.
   • Uncheck Disable Depth Test.
3. Adjust material properties:
   • Use Opacity to control translucency.
   • Add Emissive Color for glowing effects without additive blending.

What This Fix Does: Ensures the material interacts with the depth buffer, allowing LIV to render it properly with correct occlusion.

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Fixing the Permutation Error Bug on Packaged build

Context The Permutation Error occurs when Unreal Engine fails to load the LIV plugin due to an issue with the EngineVersion field in the LIV.uplugin file. This happens when switching between the stock Unreal Engine and the Meta Fork.

• Scenario 1: Stock Unreal Engine If the error occurs in the stock engine, the issue is caused by the presence of the EngineVersion field. Fix:
  1. Navigate to the LIV plugin file: [YourProjectRoot]/Plugins/LIV/LIV.uplugin
  2. Open LIV.uplugin in a text editor.
  3. Remove the EngineVersion line: "EngineVersion": "X.X.X"
  4. Save the file and restart Unreal Engine.
• Scenario 2: Meta Fork If the error occurs in the Meta Fork, the issue is caused by the absence of the EngineVersion field, or a non-exact matching EngineVersion. Fix:
  1. Navigate to the LIV plugin file: [YourProjectRoot]/Plugins/LIV/LIV.uplugin
  2. Open LIV.uplugin in a text editor.
  3. Add the correct EngineVersion line. Replace "X.X.X" with the exact Meta Fork version you are using. "EngineVersion": "5.4.3"
  4. Save the file and restart Unreal Engine. Summary

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Meta Features (Optional)

For projects using the Meta Fork and Presence Platform:

1. Enable Passthrough, Scene API, and Spatial Anchors in Plugins > Meta XR.
2. Configure the Scene API to interact with the real-world environment.
3. Test Spatial Anchors for persistent object placement across sessions.

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Meta XR Integration

The Meta XR Plugin enables advanced features such as Passthrough, Scene API, and Spatial Anchors using the Stock Unreal Engine. Requirements

• Meta XR Plugin Version: Minimum 65.0.
• Unreal Engine Version: 5.3.2 or higher.
• Location: The Meta XR Plugin must be placed in the Marketplace (or Fab) directory of the Unreal Engine installation.

Steps to Integrate the Meta XR Plugin 1. Locate or Create the Marketplace Directory The Meta XR Plugin must reside in the engine’s Marketplace folder.

• Navigate to your Unreal Engine installation directory: [UnrealEnginePath]/Engine/Plugins/Marketplace/
• If the Marketplace folder does not exist, create it manually.

2. Install the Meta XR Plugin

• Download the Meta XR Plugin (Version 65.0 or higher) from the Meta Developer Portal.
• Extract the plugin files.
• Place the extracted plugin folder (MetaXR) into the Marketplace directory: [UnrealEnginePath]/Engine/Plugins/Marketplace/MetaXR/

3. Enable the Meta XR Plugin in Unreal Engine

• Open Unreal Engine.
• Go to Edit > Plugins.
• Search for Meta XR and enable the following plugins:
  • MetaXR: For advanced Presence Platform features.
  • OculusXR: Core integration for Meta VR devices.
• Restart the Unreal Editor to apply the changes.

4. Configure Meta XR Features

• Open Edit > Project Settings > Meta XR.
• Enable the features you need:
  • Passthrough: Allows real-world visuals to blend with MR content.
  
  • Scene API: Detects and interacts with real-world geometry.
  
  • Spatial Anchors: Supports persistent placement of virtual objects.

Common Issues with Meta XR Integration

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FAQ and Tips

This section addresses common issues and provides practical tips to optimize your LIV SDK experience.

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Common Issues and Solutions

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Tips for a Smooth Workflow

Switch to DirectX 11

• The LIV SDK does not support DirectX 12.
• Go to Edit > Project Settings > Platforms > Windows and set Default RHI to DirectX 11.

Optimize Scene Performance

1. Minimize the use of translucent materials.
2. Avoid overloading the scene with dynamic lighting and complex shaders.
3. Use Stat Unit and Stat FPS commands to monitor performance.

Enable Logs for Debugging

• Run your packaged build with the log flag to view detailed logs: "[GamePath]\MyGame.exe" -log

Package Builds Correctly

1. Use Development or Shipping configuration when packaging.
2. Ensure the build is targeted for Windows 64-bit.

Test on Target Hardware

• Always test your project on the VR hardware it is intended for to identify any compatibility or performance issues early.

Monitor Logs for Issues:

• Run builds with the log flag to identify and resolve rendering errors.

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Advanced Troubleshooting

Performance Bug (UE-86191) Unreal Engine may exhibit a performance bug when using MR capture with certain configurations. To fix this:

1. Open the DefaultEngine.ini file in your project directory.
2. Add the following lines: [/Script/Engine.RendererSettings] r.SceneRenderTargetResizeMethod=2 r.SceneRenderTargetResizeMethodForceOverride=True

Command-Line Packaging

• If packaging fails in the editor, use the command line: & "[UnrealEnginePath]\Engine\Build\BatchFiles\RunUAT.bat" BuildCookRun -project="[PathToUProject]" -platform=Win64 -clientconfig=Development -serverconfig=Development -cook -build -stage -pak -archive -archivedirectory="[OutputFolder]"