Draw a cube in Swift

gistfile1.txt

import UIKit
import QuartzCore

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        // select cube rotation
        let adjustment:CGFloat = 90
        // draw cube
        let cube = drawCube(100, 250, 50, adjustment, UIColor(hue: 60/360, saturation: 80/100, brightness: 100/100, alpha: 1.0))
        for c in cube {
            self.view.layer.addSublayer(c)
        }
        
        
          }
    
    
    
}


func degree2radian(a:CGFloat)->CGFloat {
    let b = CGFloat(M_PI) * a/180
    return b
}

func polygonPointArray(sides:Int,x:CGFloat,y:CGFloat,radius:CGFloat,adjustment:CGFloat=0)->[CGPoint] {
    let angle = degree2radian(360/CGFloat(sides))
    let cx = x // x origin
    let cy = y // y origin
    let r  = radius // radius of circle
    var i = sides
    var points = [CGPoint]()
    while points.count <= sides {
        let xpo = cx - r * cos(angle * CGFloat(i)+degree2radian(adjustment))
        let ypo = cy - r * sin(angle * CGFloat(i)+degree2radian(adjustment))
        points.append(CGPoint(x: xpo, y: ypo))
        i--;
    }
    return points
}

func drawCube (x:CGFloat,y:CGFloat,radius:CGFloat, adjustment:CGFloat, color:UIColor)->[CAShapeLayer] {
    
    // --- Color is shaded with light coming from above and to the right --- //
    var h:CGFloat = 0
    var s:CGFloat = 0
    var b:CGFloat = 0
    
    color.getHue(&h, saturation: &s, brightness: &b, alpha: nil)
    
    // --- Left side of cube (visible) --- //
    let leftSide = CAShapeLayer()
    let leftSidePath = cubeLeft(x: x, y: y, radius: radius, sides: 6, adjustment:adjustment)
    leftSide.path = leftSidePath
    
    leftSide.fillColor = UIColor(hue: h, saturation: s, brightness: b*0.7, alpha: 1.0).CGColor
    
    // --- Front side of cube (visible) --- //
    let frontSide = CAShapeLayer()
    let frontSidePath = cubeFront(x: x, y: y, radius: radius, sides: 6, adjustment:adjustment)
    
    frontSide.path = frontSidePath
    frontSide.fillColor = UIColor(hue: h, saturation: s, brightness: b*0.85, alpha: 1.0).CGColor
    
    
    let topSide = CAShapeLayer()
    let topSidePath = cubeTop(x: x, y: y, radius: radius, sides: 6, adjustment:adjustment)
    topSide.path = topSidePath
    topSide.fillColor = UIColor(hue: h, saturation: s, brightness: b*0.95, alpha: 1.0).CGColor
    
    return [leftSide,frontSide,topSide]
    
}



func cubeTop(#x:CGFloat, #y:CGFloat, #radius:CGFloat, #sides:Int, #adjustment:CGFloat) -> CGPathRef {
    let path = CGPathCreateMutable()
    let points = polygonPointArray(sides,x,y,radius,adjustment: adjustment)
    var cpg = points[0]
    CGPathMoveToPoint(path, nil, cpg.x, cpg.y)
    CGPathAddLineToPoint(path, nil, points[1].x, points[1].y)
    CGPathAddLineToPoint(path, nil, x, y)
    CGPathAddLineToPoint(path, nil, points[5].x, points[5].y)
    CGPathCloseSubpath(path)
    return path
}

func cubeFront(#x:CGFloat, #y:CGFloat, #radius:CGFloat, #sides:Int, #adjustment:CGFloat) -> CGPathRef {
    let path = CGPathCreateMutable()
    let points = polygonPointArray(sides,x,y,radius,adjustment: adjustment)
    var cpg = points[5]
    CGPathMoveToPoint(path, nil, cpg.x, cpg.y)
    CGPathAddLineToPoint(path, nil, points[4].x, points[4].y)
    CGPathAddLineToPoint(path, nil, points[3].x, points[3].y)
    CGPathAddLineToPoint(path, nil, x, y)
    CGPathCloseSubpath(path)
    return path
}

func cubeLeft(#x:CGFloat, #y:CGFloat, #radius:CGFloat, #sides:Int, #adjustment:CGFloat) -> CGPathRef {
    let path = CGPathCreateMutable()
    let points = polygonPointArray(sides,x,y,radius,adjustment: adjustment)
    var cpg = points[5]
    CGPathMoveToPoint(path, nil, x, y)
    CGPathAddLineToPoint(path, nil, points[1].x, points[1].y)
    CGPathAddLineToPoint(path, nil, points[2].x, points[2].y)
    CGPathAddLineToPoint(path, nil, points[3].x, points[3].y)
    CGPathCloseSubpath(path)
    return path
}