Pixel_Projection.swift

    
    /**
    Calculate the x-pixel offset for an angle
    
    - parameter angle: The viewing angle for the object
    
    - returns: xOffset CGFloat for the x location of the object on the screen
    */
    private func getXPixelOffset(angle: Double) -> CGFloat {
        var xOffset = CGFloat(0.0)
        var fieldOfView = CGFloat(0.0)
        
        if orientation != nil && fov != nil {
            switch orientation! {
            case .Portrait, .PortraitUpsideDown:
                fieldOfView = CGFloat(fov!)
            case .LandscapeLeft, .LandscapeRight:
                fieldOfView = CGFloat(fov!) * view.frame.height / view.frame.width
            default:
                fieldOfView = CGFloat(fov!)
            }
        }
        
        if currentHeading != nil {
            let pixPerDeg = view.frame.width / CGFloat(fieldOfView)
            let viewAngle = angle - currentHeading!
            xOffset = CGFloat(viewAngle) * pixPerDeg
        }
        //Larger value = more to the right
        return xOffset + view.frame.width/2.0
    }
    
    /**
    Calculate the y-pixel offset for an angle
    
    - parameter angle: The viewing angle for the object
    
    - returns: yOffset CGFloat for the y location of the object on the screen
    */
    private func getYPixelOffset(angle: Double) -> CGFloat {
        var yOffset = CGFloat(0.0)
        var fieldOfView = CGFloat(0.0)
        
        if orientation != nil && fov != nil {
            switch orientation! {
            case .Portrait, .PortraitUpsideDown:
                fieldOfView = CGFloat(fov!) * view.frame.height / view.frame.width
            case .LandscapeLeft, .LandscapeRight:
                fieldOfView = CGFloat(fov!)
            default:
                fieldOfView = CGFloat(fov!) * view.frame.height / view.frame.width
            }
        }
        
        if currentPitch != nil {
            let pixPerDeg = view.frame.height / CGFloat(fieldOfView)
            let viewAngle = angle - currentPitch!
            yOffset = CGFloat(viewAngle) * pixPerDeg
        }
        //Larger value = lower
        return view.frame.height/2.0 - yOffset
    }