👔Polygon

💈範例

👔 Polygon

⬆️ 需要： Vector2D, floating +−⨉÷ int

// 2022.03.01

import SwiftUI
import Extensions    // FloatingPoint+
import Protocols     // Vector2D

/// an animatable polygon shape
/// ```
/// Polygon(sides: 6, scale: 1.2)
/// Polygon(5)
/// ```
public struct Polygon: Shape {
    
    var sides: CGFloat
    var scale: CGFloat = 1.0
    
    public init(sides: CGFloat, scale: CGFloat = 1.0) {
        self.sides = sides
        self.scale = scale
    }
    
    // ⭐️ `animatableData` (AnimatablePair)
    public var animatableData: AnimatablePair<CGFloat, CGFloat> {
        get { AnimatablePair(sides, scale) }
        // ⭐️ set new animation value
        set {
            sides = newValue.first
            scale = newValue.second
        }
    }
    
    public func path(in rect: CGRect) -> Path {
        
        let r = scale * rect.minSide / 2   // radius
        let c = rect.center                // polygon center
        let a0 = -0.5 * CGFloat.pi         // start angle
        let a = CGFloat.pi / sides * 2     // difference to next angle
        let n = Int(sides.rounded(.up))    // integral sides
        
        return Path { path in 
            path.move(to: c + .polar(r, a0))
            for i in 1..<n {
                path.addLine(to: c + .polar(r, a0 + a * i))
            }
            path.closeSubpath()
        }
    }
}

// convenience init
extension Polygon {
    /// `Polygon(3)`
    public init(_ n: CGFloat) {
        self.init(sides: n)
    }
}

⭐️ 重點

💈範例

📘 手冊

📗 參考

👥 相關