ios – Swift：有没有一种简单的方法来绘制形状并检测它们是否相交？

func intersectionbetweenSegments(p0: CGPoint,_ p1: CGPoint,_ p2: CGPoint,_ p3: CGPoint) -> CGPoint? {
    var denominator = (p3.y - p2.y) * (p1.x - p0.X) - (p3.x - p2.X) * (p1.y - p0.y)
    var ua = (p3.x - p2.X) * (p0.y - p2.y) - (p3.y - p2.y) * (p0.x - p2.X)
    var ub = (p1.x - p0.X) * (p0.y - p2.y) - (p1.y - p0.y) * (p0.x - p2.X)
    if (denominator < 0) {
        ua = -ua; ub = -ub; denominator = -denominator
    }

    if ua >= 0.0 && ua <= denominator && ub >= 0.0 && ub <= denominator && denominator != 0 {
        return CGPoint(x: p0.x + ua / denominator * (p1.x - p0.X),y: p0.y + ua / denominator * (p1.y - p0.y))
    }

    return nil
}

因此,如果您有一个CGPoint值数组并且想要识别所有交叉点,则可以执行以下操作：

let n = points!.count - 1

for i in 1 ..< n {
    for j in 0 ..< i-1 {
        if let intersection = intersectionbetweenSegments(points![i],points![i+1],points![j],points![j+1]) {
            // do whatever you want with `intersection`
        }
    }
}

例如,您可以在屏幕相交的屏幕上添加一个点：

但是,如果曲线由三次贝塞尔曲线组成,则更复杂.不过,您可以考虑一下Checking if two cubic Bézier curves intersect.