対称な星＠コードを学ぼう3

難しいです。初めて見る手法とかがヒントになっていてとまどうばかりでした。考え方はすんなりいくんですけれど、それをコードに表現するのが難しいですね。

// 対称な星＠コードを学ぼう3
let animals = [A, B, C, D, E, F]
var lastPlacePosition = Point(x: 0, y: 0)

func addImage(touch: Touch) {
    let placeDistance = touch.position.distance(from: lastPlacePosition)
    if placeDistance < 80
    { return }
    lastPlacePosition = touch.position
    
    // Graphics for each quadrant.
    var graphics: [Graphic] = []
    // Pick a random image.
    let chosenImage = animals.randomItem
    // Create graphics and add to array.
    for i in 0 ..< 4 {
        let graphic = Graphic(image: chosenImage)
        graphics.append(graphic)
    }
    // Get absolute x, y values.
    let x = abs(touch.position.x)
    let y = abs(touch.position.y)
    // Position a graphic in each quadrant.
    let position1 = Point(x: x, y: y)
    let position2 = Point(x: x, y: -y)
    let position3 = Point(x: -x, y: y)
    let position4 = Point(x: -x, y: -y)
    
    for i in 0 ..< 4 {
        if i == 0 {
            scene.place(graphics[i], at: position1)
        } else if i == 1 {
            scene.place(graphics[i], at: position2)
        } else if i == 2 {
            scene.place(graphics[i], at: position3)
        } else {
            scene.place(graphics[i], at: position4)
        }
    }
}