3次元におけるSwiftUI

3:35 - MoonView

struct MoonView {
  var body: some View {
    Model3D(named: "Moon") { phase in
      switch phase {
      case .empty:
        ProgressView()
      case let .failure(error):
        Text(error.localizedDescription)
      case let .success(model):
        model
          .resizable()
          .scaledToFit()
      }
    }
  }
}

17:26 - Manipulation Gesture

// Gesture combining dragging, magnification, and 3D rotation all at once.
var manipulationGesture: some Gesture<AffineTransform3D> {
    DragGesture()
        .simultaneously(with: MagnifyGesture())
        .simultaneously(with: RotateGesture3D())
        .map { gesture in
            let (translation, scale, rotation) = gesture.components()

            return AffineTransform3D(
                scale: scale,
                rotation: rotation,
                translation: translation
            )
        }
}

// Helper for extracting translation, magnification, and rotation.
extension SimultaneousGesture<
    SimultaneousGesture<DragGesture, MagnifyGesture>,
    RotateGesture3D>.Value {
    func components() -> (Vector3D, Size3D, Rotation3D) {
        let translation = self.first?.first?.translation3D ?? .zero
        let magnification = self.first?.second?.magnification ?? 1
        let size = Size3D(width: magnification, height: magnification, depth: magnification)
        let rotation = self.second?.rotation ?? .identity
        return (translation, size, rotation)
    }
}