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Hi XR Developers! In today’s post we’re tearing open Cryptic Cabinet, one of Meta’s most ambitious open-source demos. The project is packed with goodies, but we’ll focus on three main systems you can lift straight into your own apps:

1. Room-aware object placement powered by MRUK
2. Custom interactions overriding Metas’s Interaction SDK
3. Dynamic Passthrough effects for environment dimming and mood-switching

Stick around to see how each piece fits together, grab the sample, and ship your game in no time. If this helps, drop a 👍 and subscribe. Hop into our Discord to bounce questions with fellow tinkerers!

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🚀 Prerequisites & Setup

What you need	Version / Notes
Meta Quest 3 / 3 S	Horizon OS v77+
Unity	≥ 2022.3.16 LTS, Android build target
Meta XR Core SDK	v77 (includes MRUK, Passthrough, Anchors, Scene, Platform)
Photon Fusion	2.x (free 20 CCU tier is fine)
Git LFS	Handles large binary assets
Optional	Meta XR Simulator for device-free iteration

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1. Grab the Code ⬇️

# 1-time install for large file support 
git lfs install 

# Clone wherever you keep your projects 

git clone https://github.com/oculus-samples/Unity-CrypticCabinet.git

Open the newly–cloned folder in Unity Hub, select a 2022.3.16 LTS (or newer) editor, set Platform → Android, and hit Open.

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2. Wire Up Meta Platform 🔑

1. Meta Developer Center → Create App, and give it a name
2. Complete Requirements → Data Use Checkup (User ID + Profile, age group)
3. Copy the App ID from Deployment → API
4. In Unity: Meta → Platform → Edit Settings → paste ID for both Quest + Rift
5. Tick Use Standalone Platform and supply Test User creds for in-Editor login

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3. Hook Photon Fusion 🌐

1. Sign in at dashboard.photonengine.com → Create App → Fusion
2. Copy the generated App ID
3. Unity: Fusion → Realtime Settings → paste ID under Fusion section

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4. Sign & Upload the APK 📲

Step	Why
Generate Android Keystore	Every Quest APK must be signed
Unique Package Name & Bundle Version Code	Bump versionCode on every upload
Meta → Tools → Create store-compatible AndroidManifest.xml	Automates required permissions
Build Main.unity → .apk	✔️
Quest Developer Hub → App Distribution → choose Organization & Channel	Push the build
Add testers / org members	Grant entitlement before launch

That’s it—time to dive into the magic. 🪄

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🔍 Feature 1 – MRUK Auto-Placement & Room Setup

Cryptic Cabinet can drop its cupboards, desks, and gizmos exactly where they make sense in your room—no manual fiddling. The workflow:

1. Scene scan via MRUK returns walls, floors, desks, etc.
2. ObjectPlacementManager orchestrates five passes, largest-to-smallest:
   • Floor-against-wall → Walls → Desks → Floors → Any horizontal
3. SceneUnderstandingLocationPlacer harvests MRUK anchors and funnels them into dedicated finders:
   • WallSpaceFinder, DeskSpaceFinder, FloorSpaceFinder
4. Each finder tiles its surface into a 3-D grid of cells (green = free, red = blocked) with edge-distance metadata.
5. Remaining rejects? RandomlyPlaceFailedObjects sprinkles them onto valid cells.
6. The user previews blue (reachable) / green (visible) / red (invalid) boxes and nudges any red stragglers before saving the layout.

Takeaway: MRUK turns raw scene meshes into a semantic playground—just ask for RequestRandomDeskLocation() and you’re golden.

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🔧 Feature 2 – “Grab → Insert → Twist” Interactions (Keys & Light-Bulbs)

Cryptic Cabinet’s keyholes and bulb sockets feel exactly like the real thing thanks to a custom transformer trio that blends free-form grabbing with single-axis screwing:

Script	Role
OneGrabToggleRotateTransformer	Swaps between free movement and pivot-locked rotation at runtime
ScrewSnapZone	Collider that captures an inserted prop, stores it as CurrentObject, and raises events (OnSnap, OnTightened, OnUnscrew, OnRemoved)
ScrewableObject	Lives on each key/bulb, orchestrates the lock-in, lerps the “screw” motion, and fires completion callbacks

How It Works 🔩

1. OneGrabToggleRotateTransformer starts in “free” mode, mimicking OneGrabFreeTransformer, so the prop behaves like any normal grabbable.
2. Snap-In Detection
   The prop’s OnTriggerEnter with a ScrewSnapZone:

void OnTriggerEnter(Collider other) {
    if (other.TryGetComponent(out ScrewSnapZone zone)) {
        rb.isKinematic = true;                    // freeze physics
        transformer.LockPosition(zone.transform); // pivot-lock
        transformer.ResetRotation();
        zone.CurrentObject = this;
    }
}

3. Lock & Rotate
LockPosition = true freezes translation and activates the transformer’s single-axis mode (like OneGrabRotateTransformer). The public ConstrainedRelativeAngle exposes live rotation.

4. Screw Motion & Events
Each frame, ScrewableObject maps ConstrainedRelativeAngle → 0–1 turn percentage, lerping the mesh between start and tight guide poses.
OnScrewComplete fires when the angle exceeds tightThreshold; OnObjectStartUnscrew fires on the way back.

5. Break-Snap Escape
If the user yanks the prop beyond unlockBreakDistance, the transformer auto-switches back to free movement and rb.isKinematic = false, letting the player pull it out naturally.

// Inside Update of ScrewableObject
float pct = transformer.ConstrainedRelativeAngle / maxAngle;
transform.position = Vector3.Lerp(loosePose.position, tightPose.position, pct);
if (!completed && pct >= 1f) { completed = true; OnScrewComplete?.Invoke(); 
}

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🎛️ Feature 3 – Dynamic Passthrough FX

Want an eerie blackout or UV-glow on demand? Cryptic Cabinet blends LUTs and post-processing in perfect sync with gameplay.

Component	Responsibility
PassthroughChanger (singleton)	Toggles m_uvActive / m_darkActive and calls SetPassthroughLut()
PassthroughConfigurator (NetworkBehaviour)	Holds LUT textures, lerps opacity/contrast/brightness and RPCs them to peers
BlackoutVolume	When the camera’s inside props, disables renderPostProcessing to avoid seeing through geometry

// Dark mode 🌑
public void EnableDarkRoom(bool enable) {
    SetPassthroughLut(ELutId.DARKER_ROOM, enable ? 1f : 0f);
}

The result: flick a switch and everyone’s environment dims together, sharp and artifact-free.

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🧪 Testing Checklist

Host	Guest
Builds & uploads signed APK → release channel	Installs same channel
Runs scene: verifies MRUK scan, anchor broadcast	Logs show anchor reception, room load
Flips UV light / blackout	Sees identical Passthrough blend

If anything drifts, re-scan the room or check that Fusion’s Time Sync Mode is enabled so physics stay deterministic.

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🎯 Conclusion

Cryptic Cabinet bundles room-aware placement, bulletproof networking, and theatrical Passthrough in a neat open-source bow. Steal the patterns, tweak the puzzles, and launch your own mixed-reality escape room—no magic incantations required.

Liked the breakdown? Press that Like, hit Subscribe, and swing by Patreon for full source access.

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