AR Experiences in SwiftUI with RealityKit & Vision Pro

Creating Immersive AR Experiences with SwiftUI and RealityKit: A Step-by-Step Guide

What We Will Build

In this tutorial, we'll focus on creating a scene where the materials of objects in the AR environment change dynamically based on the user's position relative to them. Specifically, we will manipulate a Sphere and a Cube. As the user moves around the scene, we will change the textures applied to these models based on their orientation to the user.

Key Concepts

• RealityKit: Apple's framework for creating 3D AR experiences.
• Vision Pro: Apple's spatial computing platform for detecting the user's position and movement.
• SwiftUI: The declarative UI framework used for building user interfaces across all Apple platforms.

Step 1: Setting Up the Basic AR Scene with RealityKit

In this project, we create a view called ImmersiveView, which is powered by RealityKit's RealityView. This view contains our AR content, which is added dynamically when the app runs.

RealityView { content in

    Task { await visionProPose.runArSession() }

    if let immersiveContentEntity = try? await Entity(named: "Immersive", in: realityKitContentBundle) {

        // Add entities like Sphere and Cube to the content

        ...

    }

}

Step 2: Managing User Position with Vision Pro

We use a VisionProPosition object to track the user's position in the AR world. The user's position is updated every 0.3 seconds using a Timer.

@State private var userPosition: SIMD3<Float>? = nil

Timer.scheduledTimer(withTimeInterval: 0.3, repeats: true) { _ in

    Task { @MainActor in

        userPosition = await visionProPose.getTransform()?.translation

    }

}

This allows us to dynamically calculate the user's movement and update the AR scene accordingly.

Step 3: Dynamic Material Updates Based on User's Position

The core of this project is dynamically changing the materials applied to the Sphere and Cube. By calculating the angle between the user's position and the Sphere, we determine which side of the Sphere the user is located on. Based on the angle, we will update the textures applied to both the Sphere and the Cube.

let directionToUser = userPosition - spherePosition

let angle = atan2(directionToUser.x, directionToUser.z)

let degreeAngle = radiansToDegrees(angle)

switch degreeAngle {

case 45..<135:

    imageName = "Image1"

case -135..<(-45):

    imageName = "Image2"

case -45..<45:

    imageName = "Image3"

default:

    imageName = "Image4"

}

The imageName determines which texture to apply to both objects, based on the direction the user is facing.

Step 4: Applying Textures to Models

Now that we have the imageName based on the user's position, we use this information to load and apply different textures to the Sphere and Cube. The textures are loaded using TextureResource.load(named:), and the materials are updated accordingly.

sphere.model?.materials = [materialForSphere(named: imageName)]

cube.model?.materials = [materialForPlane(named: imageName)]

Here's how we define the material creation methods for both objects:

func materialForSphere(named imageName: String) -> SimpleMaterial {

    if let texture = try? TextureResource.load(named: imageName) {

        var glassMaterial = SimpleMaterial()

        glassMaterial.color = .init(tint: .white.withAlphaComponent(0.6), texture: .init(texture))

        glassMaterial.metallic = 0.9

        glassMaterial.roughness = 0.1

        return glassMaterial

    }

    return SimpleMaterial()

}

This materialForSphere function loads the texture and creates a translucent material with a glossy finish for the Sphere, while the materialForPlane function does the same for the Cube.

Step 5: Putting It All Together

Now that we've established our basic setup, the AR scene will continuously update based on the user's position relative to the Sphere. As the user moves, the material on both objects will change, creating an interactive experience.

content.subscribe(to: SceneEvents.Update.self) { _ in

    updateMaterialsIfNeeded(for: flattenedCube, sphere: sphere)

}

The update function checks if the user's position has changed and updates the materials of the Sphere and Cube accordingly.

By combining RealityKit, Vision Pro, and SwiftUI, we can create immersive AR experiences that are dynamic and interactive. The ability to update materials based on real-time user interactions allows for highly engaging environments.

In this example, we've used basic geometry and dynamic material updates, but there are endless possibilities for creating more complex interactions in AR. Whether you're building educational tools, gaming experiences, or interactive showcases, the concepts discussed here provide a foundation for more sophisticated AR development on Apple platforms.