Add SwiftUI visionOS example. (#115)

ExampleVisionOS/Assets.xcassets/AppIcon.solidimagestack/Back.solidimagestacklayer/Content.imageset/Contents.json

@@ -0,0 +1,12 @@
+{
+  "images" : [
+    {
+      "idiom" : "vision",
+      "scale" : "2x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

ExampleVisionOS/Assets.xcassets/AppIcon.solidimagestack/Back.solidimagestacklayer/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

ExampleVisionOS/Assets.xcassets/AppIcon.solidimagestack/Contents.json

@@ -0,0 +1,17 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  },
+  "layers" : [
+    {
+      "filename" : "Front.solidimagestacklayer"
+    },
+    {
+      "filename" : "Middle.solidimagestacklayer"
+    },
+    {
+      "filename" : "Back.solidimagestacklayer"
+    }
+  ]
+}

ExampleVisionOS/Assets.xcassets/AppIcon.solidimagestack/Front.solidimagestacklayer/Content.imageset/Contents.json

@@ -0,0 +1,12 @@
+{
+  "images" : [
+    {
+      "idiom" : "vision",
+      "scale" : "2x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

ExampleVisionOS/Assets.xcassets/AppIcon.solidimagestack/Front.solidimagestacklayer/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

ExampleVisionOS/Assets.xcassets/AppIcon.solidimagestack/Middle.solidimagestacklayer/Content.imageset/Contents.json

@@ -0,0 +1,12 @@
+{
+  "images" : [
+    {
+      "idiom" : "vision",
+      "scale" : "2x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

ExampleVisionOS/Assets.xcassets/AppIcon.solidimagestack/Middle.solidimagestacklayer/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

ExampleVisionOS/Assets.xcassets/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

ExampleVisionOS/ContentView.swift

@@ -0,0 +1,22 @@
+//
+//  ContentView.swift
+//  ExampleVisionOS
+//
+//  Created by Hal Mueller on 3/5/24.
+//  Copyright © 2024 Nick Lockwood. All rights reserved.
+//
+
+import RealityKit
+import SwiftUI
+
+struct ContentView: View {
+    @State private var enlarge = false
+
+    var body: some View {
+        VolumetricView()
+    }
+}
+
+#Preview(windowStyle: .volumetric) {
+    ContentView()
+}

ExampleVisionOS/EuclidMesh.swift

@@ -0,0 +1,26 @@
+//
+//  EuclidMesh.swift
+//  ExampleVisionOS
+//
+//  Created by Hal Mueller on 3/5/24.
+//  Copyright © 2024 Nick Lockwood. All rights reserved.
+//
+
+import CoreGraphics
+import Euclid
+
+let euclidMesh: Mesh = {
+    let start = CFAbsoluteTimeGetCurrent()
+
+    // create some geometry using Euclid
+    let cube = Mesh.cube(size: 0.8, material: Color.red)
+    let sphere = Mesh.sphere(slices: 120, material: CGImage.checkerboard())
+    let mesh = cube.subtracting(sphere).makeWatertight()
+
+    print("Time:", CFAbsoluteTimeGetCurrent() - start)
+    print("Polygons:", mesh.polygons.count)
+    print("Triangles:", mesh.triangulate().polygons.count)
+    print("Watertight:", mesh.isWatertight)
+
+    return mesh
+}()

ExampleVisionOS/ExampleVisionOSApp.swift

@@ -0,0 +1,20 @@
+//
+//  ExampleVisionOSApp.swift
+//  ExampleVisionOS
+//
+//  Created by Hal Mueller on 3/5/24.
+//  Copyright © 2024 Nick Lockwood. All rights reserved.
+//
+
+import SwiftUI
+
+@main
+struct ExampleVisionOSApp: App {
+    var body: some Scene {
+        WindowGroup {
+            ContentView()
+        }
+        .windowStyle(.volumetric)
+        .defaultSize(width: 1.5, height: 1.5, depth: 1.5, in: .meters)
+    }
+}

ExampleVisionOS/Info.plist

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>UIApplicationSceneManifest</key>
+	<dict>
+		<key>UIApplicationPreferredDefaultSceneSessionRole</key>
+		<string>UIWindowSceneSessionRoleVolumetricApplication</string>
+		<key>UIApplicationSupportsMultipleScenes</key>
+		<true/>
+		<key>UISceneConfigurations</key>
+		<dict/>
+	</dict>
+</dict>
+</plist>

ExampleVisionOS/Preview Content/Preview Assets.xcassets/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

ExampleVisionOS/VolumetricView.swift

@@ -0,0 +1,53 @@
+//
+//  VolumetricView.swift
+//  ExampleVisionOS
+//
+//  Created by Hal Mueller on 3/6/24.
+//  Copyright © 2024 Nick Lockwood. All rights reserved.
+//
+
+import RealityKit
+import SwiftUI
+
+struct VolumetricView: View {
+    @State private var spinX = 0.0
+    @State private var spinY = 0.0
+
+    var body: some View {
+        RealityView { content in
+            if let demoBoxEntity = try? ModelEntity(euclidMesh.scaled(by: 0.5)) {
+                // for more realism, add a shadow
+                demoBoxEntity.components.set(GroundingShadowComponent(castsShadow: true))
+
+                // needed for tap detection/response
+                demoBoxEntity.generateCollisionShapes(recursive: true)
+
+                // for gesture targeting
+                demoBoxEntity.components.set(InputTargetComponent())
+
+                content.add(demoBoxEntity)
+            }
+        } update: { content in
+            guard let entity = content.entities.first else { return }
+
+            let pitch = Transform(pitch: Float(spinX * -1)).matrix
+            let yaw = Transform(yaw: Float(spinY)).matrix
+            entity.transform.matrix = pitch * yaw
+        }
+        .gesture(
+            DragGesture(minimumDistance: 0)
+                .targetedToAnyEntity()
+                .onChanged { value in
+                    let startLocation = value.convert(value.startLocation3D, from: .local, to: .scene)
+                    let currentLocation = value.convert(value.location3D, from: .local, to: .scene)
+                    let delta = currentLocation - startLocation
+                    spinX = Double(delta.y) * 5
+                    spinY = Double(delta.x) * 5
+                }
+        )
+    }
+}
+
+#Preview {
+    VolumetricView()
+}

README.md

@@ -58,9 +58,10 @@ Feel free to open an issue in Github if you have questions about how to use the
 If you wish to contribute improvements to the documentation or the code itself, that's great! But please read the [CONTRIBUTING.md](CONTRIBUTING.md) file before submitting a pull request.
 
 
-# Example
+# Example and ExampleVisionOS
 
-See the included project for an example of how Euclid can be used in conjunction with SceneKit or RealityKit to generate and render a nontrivial 3D shape on iOS.
+See the included projects for examples of how Euclid can be used in conjunction with SceneKit or RealityKit to generate and render a nontrivial 3D shape. `Example` uses storyboards, is built for iOS, and runs in "Designed for iPad" mode on macOS and visionOS.
+`ExampleVisionPro` uses SwiftUI and a RealityView in a volumetric window, and runs only on visionOS.
 
 
 # Documentation