canvas, ex12.02.2018

class MyDrawings: UIView {

    /*
    // Only override draw() if you perform custom drawing.
    // An empty implementation adversely affects performance during animation.
    override func draw(_ rect: CGRect) {
        // Drawing code
    }
    */

    override func draw(_ rect: CGRect) {
         let context=UIGraphicsGetCurrentContext()
        context?.setLineWidth(2.5)
        context?.setStrokeColor(UIColor.purple.cgColor)

        //drawTriangle(context: context,p1: CGPoint(x: 0, y: 0), p2: CGPoint(x: rect.width, y: rect.height/2), p3: CGPoint(x: rect.width/2, y: rect.height))
        var p1=CGPoint(x: rect.width/2, y: 10)
        var p2=CGPoint(x: 10, y: rect.height-10)
        var p3=CGPoint(x: rect.width-10, y: rect.height-10)

        for _ in 1...5 {
            context?.move(to: p1)
            context?.addLine(to: p2)
            context?.addLine(to: p3 )
            context?.addLine(to: p1)
            context?.strokePath()

            let temp = p1
            p1=mid(p1:p1,p2:p2)
            p2=mid(p1:p2,p2:p3)
            p3=mid(p1:p3, p2:temp)
        }
    }

    func mid(p1:CGPoint, p2:CGPoint) -> CGPoint {
        return CGPoint(x: (p1.x+p2.x)/2, y: (p1.y+p2.y)/2)
    }

}