Created
April 23, 2015 14:56
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Spirograph playground based on Erica Sadun's
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| import UIKit | |
| import Foundation | |
| import XCPlayground | |
| struct SpirographGenerator : GeneratorType { | |
| var pointOffset, dTheta, dR, minorRadius, majorRadius : Double | |
| var theta = 0.0 | |
| typealias Element = CGPoint | |
| init(majorRadius : Double, minorRadius : Double, pointOffset : Double, samples : Double) | |
| { | |
| self.pointOffset = pointOffset | |
| self.dTheta = Double(M_PI) * (2.0) / samples | |
| self.majorRadius = majorRadius | |
| self.minorRadius = minorRadius | |
| self.dR = majorRadius - minorRadius | |
| } | |
| mutating func next() -> CGPoint? { | |
| var xT : Double = dR * cos(theta) + pointOffset * cos(dR * theta / minorRadius) | |
| var yT : Double = dR * sin(theta) + pointOffset * sin (dR * theta / minorRadius) | |
| theta = theta + dTheta | |
| return CGPoint(x: xT, y: yT) | |
| } | |
| } | |
| class SpiroView : UIView { | |
| var gen:SpirographGenerator = SpirographGenerator(majorRadius: 100, minorRadius: 12, pointOffset: 22, samples: 500) | |
| var points:Int = 50 { | |
| didSet { | |
| setNeedsDisplay() | |
| } | |
| } | |
| var strokeColor:UIColor = UIColor.whiteColor() | |
| override func drawRect(rect: CGRect) { | |
| let midX = rect.width / 2 | |
| let midY = rect.height / 2 | |
| let ctx = UIGraphicsGetCurrentContext() | |
| strokeColor.set() | |
| for x in 1..<points { | |
| if let p = gen.next() { | |
| CGContextAddEllipseInRect(ctx, CGRect(x: p.x + midX, y: p.y + midY, width: 1, height: 1)) | |
| } | |
| } | |
| CGContextDrawPath(ctx, kCGPathFillStroke) | |
| } | |
| } | |
| let v = SpiroView(frame: CGRect(x:0, y:0, width:250, height:250)) | |
| v.strokeColor = UIColor.redColor() | |
| v.points = 8000 |
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