The Custom Scene Manager sample is a single Unity scene that contains a Scene Manager Unity game object with multiple scripts. Each script is an example of a custom Scene Manager, and only one should be enabled when running the sample.

Try out each of the Scene Managers by toggling its script and hitting Play in-Editor. The snapshot and dynamic scene managers require you to launch Space Setup within the application, and should therefore be run on-device.

As the scenes require a Scene Model, you should have run Space Setup before trying the sample. All scripts have a fallback for requesting Space Setup/Scene Capture if no anchors were returned when looking for room anchors.

Basic Scene Manager

Basic Scene Manager is the minimal example to spawn Unity content for Scene data. When the script starts, it loads the Scene data and spawns Unity primitives with a random color in the correct location.

This is done as follows:

Fetch all anchors that have the component OVRRoomLayout.

Create a Unity game object for each room.

Iterate over all room anchors, and get the contents through the OVRAnchorContainer component.

Iterate over all child anchors and perform the following steps.

Localize each anchor by setting the enabled state of the OVRLocatable component to true.

Create a new Unity game object, parented to the room. Name it with the labels retrieved through the OVRSemanticLabels component.

Set the transform using the OVRLocatable.TrackingSpacePose and the TrackingSpace transform on the OVRCameraRig .

If an OVRBounded2D component exists, create a new child Unity game object (using the cube primitive), set the transform to the dimensions of the bounds and set the MeshRenderer material to a random color.

If an OVRBounded3D component exists, create a new child Unity game object (using the cube primitive), set the transform to the dimensions of the bounds and set the MeshRenderer material to a random color.

If an OVRTriangleMesh component exists, create a new child Unity game object (using the quad primitive), create a new Unity Mesh with the component data, update the mesh of the MeshCollider and MeshRenderer components and set the MeshRenderer material to a random color.

After the data has been spawned, you are finished and will not perform any further updates. However, it is common to update the transform from the OVRLocatable as tracking moves the object to apply corrections, but the Basic Scene Manager doesn’t do this.

Basic Scene Manager - Unity primitives spawned for Scene data

Prefab Scene Manager

The Prefab Scene Manager extends the Basic Scene Manager to filter depending on the semantic classification and spawning a user-supplied prefab for walls, ceiling, floor, and spawning a fallback prefab for all other objects.

The differences to the Basic Scene Manager are as follows:

Instead of spawning Unity primitives, spawn a user-supplied prefab instead. This prefab is still spawned as a parent of the Unity game object that is responsible for being positioned by OVRLocatable.TrackingSpacePose.

The logic to size the Unity game engine is split between the 2D objects (walls, ceiling and floor) and the 3D objects (all under the fallback prefab).

The spawned prefabs contain the label of the Scene Anchor so that they can be viewed through the headset.

All the OVRLocatable objects are cached when loading. This allows us to refresh the poses (such as when recentering or when the camera’s tracking space has changed), which this app demonstrates by simply performing a refresh every 5 seconds.

While the Prefab scene manager is still fairly primitive, it closely matches the core functionality of the OVRSceneManager.

Basic Scene Manager - user prefabs spawned for Scene data

Snapshot Scene Manager

Snapshot Scene Manager differs from the static model of loading data a single time, and instead periodically loads all the Scene data, performing a comparison between different snapshots and logging the differences to the debug console.

It works as follows:

Every 5 seconds, the system creates a snapshot of the Scene data. The snapshot consists only of a list of OVRAnchors.

The system compares snapshots in 3 steps, comparing anchors between the snapshots and performing a special comparison for new rooms.

Iterate over all the anchors in snapshot 1 and check if the anchor is in snapshot 2. If not, then it is assumed to be deleted or missing.

Iterate over all the anchors in snapshot 2 and check if the anchor is in snapshot 1. If not, then it is assumed to be new.

Iterate over all new anchors that are rooms. If any of the room’s children are in the other snapshot, then this room has been changed, otherwise it is a new room.

Each change is logged to Unity’s Debug Log.

The Snapshot Scene Manager assumes a dynamic Scene Model where not all anchors are available when querying the Scene data the first time.

Dynamic Scene Manager

The Dynamic Scene Manager builds on Snapshot Scene Manager and links all changes to spawned Unity game objects that can be updated as the Scene data is changed.

It works as follows:

Collect a snapshot of the Scene data periodically, similar to Snapshot Scene Manager. The snapshot has been extended from a list of OVRAnchors to also containing bounds and child anchors information.

The system performs the same snapshot comparison as Snapshot Scene Manager for anchors and rooms, though the system can now use the cached child anchors in the snapshots.

Beyond the basic comparison, the system performs a bounds comparison for all anchors in a room identified as changed by the previous step.

The system gets a list of all the changes between 2 snapshots and apply updates to the Unity objects.

For new objects, the system spawns Unity game objects like Basic Scene Manager.

For deleted/missing objects, the system simply deletes the Unity game object.

For changed objects, the system resets the location transform, and update the bounds or mesh if such a component exists on the object.

The Unity objects contain a reference to a OVRAnchor from a previous snapshot. This is updated by finding OVRAnchor pairs between the snapshots.

Similar to Snapshot Scene Manager, Dynamic Scene Manager assumes a dynamic Scene Model. It also provides an important optimization over the OVRSceneManager by updating content, instead of respawning all content.

Key assets

Basic Scene Manager script | .\Assets\Samples\...\Mixed Reality Sample\Scripts\CustomSceneManager | This script creates Unity primitives for all elements of the Scene.

Prefab Scene Manager script | .\Assets\Samples\...\Mixed Reality Sample\Scripts\CustomSceneManager | This script instantiates user-provided prefabs for certain elements of the Scene.

Snapshot Scene Manager script | .\Assets\Samples\...\Mixed Reality Sample\Scripts\CustomSceneManager | This script will poll the Scene data, save snapshots at each poll, and log any changes to the console.

Scene Manager helper script | .\Assets\Samples\...\Mixed Reality Sample\Scripts\CustomSceneManager | This helper script is used by the other scene manager scripts to share common code.

Dynamic Scene Manager script | .\Assets\Samples\...\Mixed Reality Sample\Scripts\CustomSceneManager | This script extends the Snapshot scene manager by maintaining a link of Unity game objects for Scene data snapshots to allow updates.

Dynamic Scene Manager helper script | .\Assets\Samples\...\Mixed Reality Sample\Scripts\CustomSceneManager | This helper script is used by the Dynamic scene manager to help the legibility of the core functionality.

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