Swift UIBezierPath不同坐标起点

Question

我找到了一个 UIBezierPath 箭头。我的目标是向函数 "addArrows" 传递玩家数组列表并在它们之间绘制箭头。这段代码很好用……除非我调用 addArrows(gameScene: scene, from: [1, 3], to: [1, 3]) 或 addArrows(gameScene: scene, from: [2, 3], to: [2, 3])。这应该在玩家 1 和 3（第一次调用）以及玩家 2 和 3（第二次调用）之间创建箭头。但是，它在玩家 2 和 3（第一次通话）和玩家 1 和 3（第二次通话）之间创建箭头。我已将 print 语句添加到 "addArrows" 函数，它会正确返回玩家的位置（位于我的常量结构中）。如果输入 [1, 2, 3] 和 [1, 2, 3] 或 [1, 2] 和 [1, 2] 的数组，它就会工作。这里究竟发生了什么？

struct K {
static let stackPositions = [
    // Player 1
    1: CGPoint(x: (_screenW / 2), y: cardHeightConstant + cardHeight + 60),
    // Player 2
    2: CGPoint(x: (_screenW / 2), y: _screenH - cardHeightConstant - cardHeight - 60),
    // Player 3
    3: CGPoint(x: 30, y: _screenH / 2),
    // Player 4
    4: CGPoint(x: _screenW - 30, y: _screenH / 2)
]
}

// 
extension UIBezierPath {
func addArrow(start: CGPoint, end: CGPoint, pointerLineLength: CGFloat, arrowAngle: CGFloat) {
    self.move(to: start)
    self.addLine(to: end)

    let startEndAngle = atan((end.y - start.y) / (end.x - start.x)) + ((end.x - start.x) < 0 ? CGFloat(Double.pi) : 0)
    let arrowLine1 = CGPoint(x: end.x + pointerLineLength * cos(CGFloat(Double.pi) - startEndAngle + arrowAngle), y: end.y - pointerLineLength * sin(CGFloat(Double.pi) - startEndAngle + arrowAngle))
    let arrowLine2 = CGPoint(x: end.x + pointerLineLength * cos(CGFloat(Double.pi) - startEndAngle - arrowAngle), y: end.y - pointerLineLength * sin(CGFloat(Double.pi) - startEndAngle - arrowAngle))

    self.addLine(to: arrowLine1)
    self.move(to: end)
    self.addLine(to: arrowLine2)
}
}

func addArrows(gameScene: GameScene, from: [Int], to: [Int]) {

for fromPlayerNumber in from {
    for toPlayerNumber in to {
        guard let fromPos = K.stackPositions[fromPlayerNumber] else { return }
        guard let toPos = K.stackPositions[toPlayerNumber] else { return }
        if fromPos == toPos { continue }

        print(fromPos.y)
        print(toPos.y)
        let arrow = UIBezierPath()
        arrow.addArrow(start: CGPoint(x: fromPos.x, y: fromPos.y),
                       end: CGPoint(x: toPos.x, y: toPos.y),
                       pointerLineLength: 7,
                       arrowAngle: CGFloat(Double.pi / 4))

        let arrowLayer = CAShapeLayer()
        arrowLayer.strokeColor = UIColor.black.cgColor
        arrowLayer.lineWidth = 1.0
        arrowLayer.path = arrow.cgPath
        arrowLayer.fillColor = UIColor.clear.cgColor
        arrowLayer.lineJoin = CAShapeLayerLineJoin.round
        arrowLayer.lineCap = CAShapeLayerLineCap.round
        gameScene.view?.layer.addSublayer(arrowLayer)
    }
}

}

编辑

我已将 "From" 位置强制设为 CGPoint(x: 0, y: 0)。这是从屏幕左上角开始的箭头，而不是从屏幕左下角开始的所有其他参考。因此，看起来箭头使用的锚点与我场景中的其他对象不同。我尝试设置 arrowLayer.anchorPoint = CGPoint(x: 0, y: 0)，但没有用...

Answer 1

在这里，坐标系参考屏幕的左上角而不是左下角。为了解决这个问题，我需要做的就是 "invert" 开始和结束 y 点的 y 坐标。修正如下：

    func addArrow(start: CGPoint, end: CGPoint, pointerLineLength: CGFloat, arrowAngle: CGFloat) {

        // Adjust Y Directions Here! // 
        let adjStart = CGPoint(x: start.x, y: K._screenH - start.y)
        let adjEnd = CGPoint(x: end.x, y: K._screenH - end.y)

        self.move(to: adjStart)
        self.addLine(to: adjEnd)

        let startEndAngle = atan((adjEnd.y - adjStart.y) / (adjEnd.x - adjStart.x)) + ((adjEnd.x - adjStart.x) < 0 ? CGFloat(Double.pi) : 0)
        let arrowLine1 = CGPoint(x: adjEnd.x + pointerLineLength * cos(CGFloat(Double.pi) - startEndAngle + arrowAngle),
                                 y: adjEnd.y - pointerLineLength * sin(CGFloat(Double.pi) - startEndAngle + arrowAngle))
        let arrowLine2 = CGPoint(x: adjEnd.x + pointerLineLength * cos(CGFloat(Double.pi) - startEndAngle - arrowAngle),
                                 y: adjEnd.y - pointerLineLength * sin(CGFloat(Double.pi) - startEndAngle - arrowAngle))

        self.addLine(to: arrowLine1)
        self.move(to: adjEnd)
        self.addLine(to: arrowLine2)
    }

Swift UIBezierPath不同坐标起点

Swift UIBezierPath Different Coordinate Starting Point

swift

uikit

uibezierpath