Platform: Meta Quest 3 (Unity)
Genre: Mixed Reality Survival Shooter
Theme: North Pole Containment / Thermal Defense

Overview

Today, the “iceblobs” evolved from static spawns into active threats. To make them chase the player, I needed a way for them to navigate the physical room. This is tricky in Mixed Reality because we don’t know the room layout until the game starts.

I solved this by generating a Navigation Mesh (NavMesh) at runtime, using the data scanned by the Quest 3.

1. The Challenge: Navigation in Mixed Reality

In a standard game, you “bake” the NavMesh (the walkable floor area) in the Unity Editor. In Mixed Reality, the “level” is the player’s living room, which changes for every user.

We need a system that:

-Waits for the room scan to load. -Identifies the floor and obstacles (tables, couches). -Generates a NavMesh on the fly.

2. Runtime NavMesh Generation

I created a script called RuntimeNavmeshBuilder to handle this dynamic baking.

How It Works Integration with MRUK: The script registers a callback with the Meta MR Utility Kit (MRUK). It waits for the SceneLoaded event, which fires once the Quest has finished scanning and loading the room geometry.

Building the Mesh: Once the scene is ready, it calls navMeshSurface.BuildNavMesh(). This function (from Unity’s AI Navigation package) analyzes the newly created room mesh and calculates where agents can walk. Result: The real-world floor becomes a valid pathfinding surface, and furniture becomes obstacles that enemies must walk around.

3. Enemy AI

With the NavMesh in place, I added a simple brain to the enemies using enemy.cs

NavMeshAgent: Each enemy has a NavMeshAgent component. This handles the physics of moving along the NavMesh.

Targeting: In the Update loop, the enemy constantly sets its destination to Camera.main.transform.position (the player’s head). Chase: The agent automatically calculates the shortest path around obstacles to reach the player. Now, if you hide behind your real-world couch, the iceblobs will actually have to pathfind around it to get to you!

4. Unity

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5. References

https://www.youtube.com/watch?v=pZ5vLcyjois&t=1574s