Calculate PI

ContentView.swift

//
//  ContentView.swift
//  CalculatePi
//
//  Created by John Haney on 3/14/24.
//

import SwiftUI
import Combine

struct ContentView: View {
    @State var sticks: [(CGPoint, CGPoint)] = []
    @State var timer = Timer.publish(every: 0.1, on: .main, in: .common).autoconnect()
    var sticksCrossing: Int {
        sticks.filter({
            let bottom: CGFloat = 40.0 * ceil($0.0.y / 40.0)
            let top: CGFloat = $0.1.y
            return bottom < top
        }).count
    }
    var estimation: CGFloat {
        let crossing = sticksCrossing
        guard crossing > 0 else { return 0 }
        return 2 * CGFloat(sticks.count) / CGFloat(crossing)
    }
    var body: some View {
        VStack {
            Text("Sticks: \(sticks.count)")
            Text("Sticks Crossing: \(sticksCrossing)")
            Text("Pi: \(estimation)")
            Canvas { context, size in
                do {
                    var path = Path()
                    path.addRects([
                        CGRect(x: 0, y: 0, width: size.width, height: size.height*0.1),
                        CGRect(x: 0, y: size.height*0.2, width: size.width, height: size.height*0.1),
                        CGRect(x: 0, y: size.height*0.4, width: size.width, height: size.height*0.1),
                        CGRect(x: 0, y: size.height*0.6, width: size.width, height: size.height*0.1),
                        CGRect(x: 0, y: size.height*0.8, width: size.width, height: size.height*0.1),
                    ])
                    context.fill(path, with: .color(.gray))
                }
                var path = Path()
                for (point, point2) in sticks {
                    path.move(to: point)
                    path.addLine(to: point2)
                }
                context.stroke(path, with: .color(.orange))
            }
            .frame(width: 300, height: 400)
            Button("Drop") {
                dropStick()
            }
        }
        .monospacedDigit()
        .onReceive(timer, perform: { _ in
            dropStick()
        })
    }
    
    func dropStick() {
        let x = CGFloat.random(in: 40...260)
        let y = CGFloat.random(in: 40...360)
        let angle = Angle(degrees: .random(in: 0...360))
        let x2 = x + 40 * cos(angle.radians)
        let y2 = y + 40 * sin(angle.radians)
        let points = [
            CGPoint(x: x, y: y),
            CGPoint(x: x2, y: y2)
        ].sorted(by: { $0.y < $1.y })
        sticks.append((points[0], points[1]))
    }
}