Mixed Reality Utility Kit – Place content with scene data

• Automatically place prefabs on semantic anchors with AnchorPrefabSpawner, configuring scaling, alignment, and selection modes.
• Scatter content dynamically on surfaces using FindSpawnPositions with random sampling and physics overlap checks.
• Precisely raycast against scene mesh colliders via Unity Physics.Raycast for manual placement.
• Hook into the MRUK.Instance.SceneLoadedEvent to safely run placement logic after scene data is ready.
• Configure and filter scene mesh colliders or EffectMesh for reliable raycast hits and placement accuracy.

AnchorPrefabSpawner: Spawn and size prefabs automatically on MRUK anchors.

FindSpawnPositions: Generate random positions on specified surfaces and spawn items.

Unity Physics.Raycast: Cast rays against the scene mesh for manual placement.

• SpawnOnStart: Controls whether the AnchorPrefabSpawner is automatically applied to all rooms, a specific room, or no rooms, allowing for manual application if desired.
• PrefabsToSpawn: One or more AnchorPrefabGroup entries—each groups a semantic label with a prefab list.
• SelectionMode:
  • Random for nondeterministic choice (use SeedValue for repeatability).
  • ClosestSize picks the prefab whose size best matches the anchor.
  • Custom to override via CustomPrefabSelection().
• ScalingMode:
  • Stretch to exactly match anchor extents.
  • UniformScaling preserves aspect ratio on all axes.
  • UniformXZScale scales horizontally but not vertically.
  • NoScaling leaves prefab at original size.
  • Custom for CustomPrefabScaling().
• AlignMode:
  • Automatic: base-align volumes, center-align planes.
  • Bottom or Center for explicit offsets.
  • NoAlignment or Custom via CustomPrefabAlignment().
• SeedValue: Random seed for deterministic selection.

using UnityEngine;
using Meta.XR.MRUtilityKit;

public class KeyWallFrameSpawner : MonoBehaviour
{
    [Tooltip("Reference your pre-configured AnchorPrefabSpawner")]
    public AnchorPrefabSpawner spawner;

    // Call this method from the MRUK SceneLoadedEvent
    public void OnSceneLoaded()
    {
        // 1. Find the 'key wall' anchor (the largest unobstructed wall)
        Vector2 wallScale;
        var keyWall = MRUK.Instance.GetCurrentRoom().GetKeyWall(out wallScale);

        // 2. Spawn a single prefab on that anchor
        spawner.SpawnPrefab(keyWall);
    }
}

Virtual Home

This sample uses Spawner_VirtualHomeFurniture and AnchorPrefabSpawner to place VH_‑prefixed furniture on semantic anchors. Beds and couches auto‑face away from walls, and four plant variants are randomly chosen. Meshes resize with GridsliceResizer to keep features (e.g., table legs) square.

View sample

• SpawnOnStart: Begin spawning in Start().
• SpawnObject: The prefab to instantiate.
• SpawnAmount: Total instances to place.
• Labels: Array of MRUKAnchor.SceneLabels (e.g., Floor, Wall).
• SpawnLocation: Choose AnySurface, VerticalSurfaces, OnTopOfSurfaces, etc.
• CheckOverlaps: Enable Physics.OverlapBox using OverlapLayerMask.
• MaxIterations: Limit retries to avoid infinite loops.
• SurfaceClearanceDistance: Minimum clearance from existing colliders.

using UnityEngine;
using Meta.XR.MRUtilityKit;

public class ScatterOnFloor : MonoBehaviour
{
    [Tooltip("Drag your FindSpawnPositions component here")]
    public FindSpawnPositions spawner;

    [Tooltip("Which semantic surfaces to spawn on (e.g. Floor)")]
    public MRUKAnchor.SceneLabels[] labels = new[] { MRUKAnchor.SceneLabels.Floor };

    [Tooltip("How many objects to spawn")]
    public int spawnAmount = 10;

    [Tooltip("Retry up to this many times to avoid overlaps")]
    public int maxIterations = 50;

    [Tooltip("Check physics overlaps before placing")]
    public bool checkOverlaps = true;

    // Call this method from the MRUK SceneLoadedEvent
    public void OnSceneLoaded()
    {
        // Configure spawner with clear, descriptive fields
        spawner.Labels = labels;
        spawner.SpawnAmount = spawnAmount;
        spawner.MaxIterations = maxIterations;
        spawner.CheckOverlaps = checkOverlaps;

        // Begin spawning once the scene model is ready
        spawner.StartSpawn();
    }
}

FloorZone

This sample uses three FindSpawnPositions instances to locate small, medium, and large floor areas, spawning circles that never intersect walls or furniture. Colliders are provided by two EffectMesh instances (with Colliders enabled), and the scene script calls CreateMesh() before StartSpawn() on SceneLoadedEvent to ensure correct ordering.

View sample

MultiSpawn

This sample demonstrates five FindSpawnPositions configurations, floating cubes, red wall tiles, green floor tiles, light‑green surface tiles, and blue ceiling tiles, using EffectMesh colliders first, then calling StartSpawn() on SceneLoadedEvent for each spawner.

View sample

• Add a MeshCollider to your global SceneMesh GameObject
• Or enable Add Colliders on the EffectMesh prefab
• Assign those GameObjects to a sceneMeshLayer for filtering

using UnityEngine;
using Meta.XR.MRUtilityKit;

public class SceneMeshPlacer : MonoBehaviour
{
    public Transform controller;
    public GameObject prefabToPlace;
    public LayerMask sceneMeshLayer;

    void Update()
    {
        if (OVRInput.GetDown(OVRInput.RawButton.RIndexTrigger))
        {
            var ray = new Ray(controller.position, controller.forward);
            if (Physics.Raycast(ray, out var hit, 100f, sceneMeshLayer))
            {
                Instantiate(prefabToPlace, hit.point, Quaternion.LookRotation(hit.normal));
            }
        }
    }
}

• Overview Get an overview of MRUK’s key areas and features.
• Getting Started Set up your project, install MRUK, and understand space setup with available Building Blocks.
• Place Content without Scene Use Environment Raycasting to place 3D objects into physical space with minimal setup.
• Manage Scene Data Work with MRUKRoom, EffectMesh, anchors, and semantic labels to reflect room structure.

• Manipulate Scene Visuals Replace or remove geometry, apply effects, and adapt scenes using semantics and EffectMesh.
• Track Objects in MRUK Track keyboards using MRUK-trackables.

• Share Your Space with Others Use MRUK’s Space Sharing API to sync scene geometry across multiple users.
• Debug Your MRUK App Use tools like the Scene Debugger and EffectMesh to validate anchor data and scene structure.

• MRUK Samples Explore sample scenes like NavMesh, Virtual Home, Scene Decorator, and more.
• Mixed Reality Motifs Instant Content Placement.

• Mixed Reality Best Practices Design MR apps that are comfortable, intuitive, and immersive.