Base

Package.swift

@@ -5,11 +5,15 @@ import PackageDescription
 
 let package = Package(
     name: "Prism",
+    platforms: [
+        .iOS(.v15),
+    ],
     products: [
         // Products define the executables and libraries a package produces, and make them visible to other packages.
         .library(
             name: "Prism",
-            targets: ["Prism"]),
+            targets: ["Prism"]
+        ),
     ],
     dependencies: [
         // Dependencies declare other packages that this package depends on.
@@ -20,9 +24,8 @@ let package = Package(
         // Targets can depend on other targets in this package, and on products in packages this package depends on.
         .target(
             name: "Prism",
-            dependencies: []),
-        .testTarget(
-            name: "PrismTests",
-            dependencies: ["Prism"]),
+            dependencies: [],
+            path: "Sources"
+        ),
     ]
 )

Sources/PrismCanvas.swift

@@ -0,0 +1,17 @@
+//
+//  PrismCanvas.swift
+//  Prism
+//
+//  Created by A. Zheng (github.com/aheze) on 9/26/22.
+//  Copyright © 2022 A. Zheng. All rights reserved.
+//
+
+
+import SwiftUI
+
+struct PrismCanvas<Content: View>: View {
+    @ViewBuilder let content: Content
+    var body: some View {
+        content
+    }
+}

Sources/PrismEffect.swift

@@ -0,0 +1,86 @@
+//
+//  PrismEffect.swift
+//  Prism
+//
+//  Created by A. Zheng (github.com/aheze) on 9/26/22.
+//  Copyright © 2022 A. Zheng. All rights reserved.
+//
+
+
+import SwiftUI
+
+extension View {
+    func tiltLeft(tilt: CGFloat) -> some View {
+        modifier(
+            PrismLeftEffect(tilt: tilt)
+        )
+    }
+
+    func tiltRight(tilt: CGFloat) -> some View {
+        modifier(
+            PrismLeftEffect(tilt: tilt)
+        )
+    }
+
+    func tiltContent(tilt: CGFloat) -> some View {
+        modifier(
+            PrismContentEffect(tilt: tilt)
+        )
+    }
+}
+
+struct PrismLeftEffect: GeometryEffect {
+    var tilt: CGFloat
+
+    var animatableData: CGFloat {
+        get { tilt }
+        set { tilt = newValue }
+    }
+
+    func effectValue(size: CGSize) -> ProjectionTransform {
+        return ProjectionTransform(
+            CGAffineTransform(a: 1, b: 0, c: tilt, d: 1, tx: 0, ty: 0)
+        )
+    }
+}
+
+struct PrismRightEffect: GeometryEffect {
+    var tilt: CGFloat
+
+    var animatableData: CGFloat {
+        get { tilt }
+        set { tilt = newValue }
+    }
+
+    func effectValue(size: CGSize) -> ProjectionTransform {
+        return ProjectionTransform(
+            CGAffineTransform(a: tilt, b: tilt + (1 - tilt), c: 0, d: 1, tx: 0, ty: 0)
+        )
+    }
+}
+
+struct PrismContentEffect: GeometryEffect {
+    var tilt: CGFloat
+
+    var animatableData: CGFloat {
+        get { tilt }
+        set { tilt = newValue }
+    }
+
+    func effectValue(size: CGSize) -> ProjectionTransform {
+        let tx: CGFloat = size.height * tilt / 2
+        let ty: CGFloat = size.width * tilt / 2
+
+        return ProjectionTransform(
+            CGAffineTransform(
+                a: 1,
+                b: tilt,
+                c: -tilt,
+                d: 1,
+                tx: tx,
+                ty: -ty
+            )
+        )
+    }
+}
+

Sources/PrismView.swift

@@ -0,0 +1,75 @@
+//
+//  PrismView.swift
+//  Prism
+//
+//  Created by A. Zheng (github.com/aheze) on 9/26/22.
+//  Copyright © 2022 A. Zheng. All rights reserved.
+//
+
+import SwiftUI
+
+struct PrismView<Content: View, Left: View, Right: View>: View {
+    var size: CGSize
+    var tilt: CGFloat
+    var extrusion: CGFloat
+    var levitation = CGFloat(0)
+    var shadowColor = Color.black
+    var shadowOpacity = CGFloat(0.25)
+
+    @ViewBuilder let content: Content
+    @ViewBuilder let left: Left
+    @ViewBuilder let right: Right
+
+    var body: some View {
+        let topRightOffset = tilt * size.width
+        let topAngle = atan2(topRightOffset, size.width)
+
+        let extrusionOffset: CGFloat = {
+            let extrusionOffset = extrusion
+            return extrusionOffset
+        }()
+
+        let levitationXOffset = sin(topAngle) * levitation
+        let levitationYOffset = cos(topAngle) * levitation
+        let extrusionXOffset = sin(topAngle) * extrusionOffset
+        let extrusionYOffset = cos(topAngle) * extrusionOffset
+
+        content
+            .frame(width: size.width, height: size.height)
+            .background(alignment: .bottom) {
+                left
+                    .frame(width: size.width, height: extrusionYOffset)
+                    .tiltLeft(tilt: tilt)
+                    .offset(y: extrusionYOffset)
+            }
+            .background(alignment: .trailing) {
+                Color.clear
+                    .frame(width: extrusionYOffset, height: size.height)
+                    .overlay(
+                        right
+                            .frame(width: size.height, height: extrusionYOffset)
+                            .rotationEffect(.degrees(-90))
+                    )
+                    .tiltRight(tilt: tilt)
+                    .offset(x: extrusionYOffset)
+            }
+            .background(
+                shadowColor
+                    .shadow(
+                        color: shadowColor,
+                        radius: 16,
+                        x: 0,
+                        y: 0
+                    )
+                    .offset(
+                        x: levitationXOffset + extrusionXOffset + 10,
+                        y: levitationYOffset + extrusionYOffset + 10
+                    )
+                    .opacity(shadowOpacity)
+                    .opacity(CGFloat(1) - (CGFloat(levitation) / 400))
+                    .blur(radius: 10 + CGFloat(levitation) / 12)
+            )
+            .offset(x: -levitationXOffset, y: -levitationYOffset) /// z height effect
+            .offset(x: -extrusionXOffset, y: -extrusionYOffset) /// extrusion effect
+    }
+}