/* Coordinate transformation
   This example implements a method Transform, which processes an
   array of points in such a way that it applies an operation--
   specified by a lambda expression--to every point.
------------------------------------------------------------*/
using System;

struct Point {
  public double x, y;
  public Point(double x, double y) { this.x = x; this.y = y; }
}

public class A4 {
  
  // Transformation applicable to an array of points
  static Point[] Transform(Point[] points, Func< Point, Point > transform) {
    Point[] res = new Point[points.Length];
    for (int i = 0; i < points.Length; i++) {
      res[i] = transform(points[i]);
    }
    return res;
  }
  
  static void Print(string caption, Point[] points) {
    Console.WriteLine(caption);
    foreach (Point p in points) Console.Write("({0:f1}, {1:f1}) ", p.x, p.y);
    Console.WriteLine();
  }
  
  public static void Main() {
    //-- Generate a Point array
    Point[] points = new Point[] {
      new Point(0, 0),
      new Point(3, 0),
      new Point(3, 3),
      new Point(0, 3)
    };
    Print("Points: ", points);
    
    //-- Move it by (5, 5)
    Point[] result = Transform(points, p => new Point(p.x + 5, p.y + 5));
    Print("Move by (5,5): ", result);
    
    //-- Scale it by a factor 2 relative to the origin
    result = Transform(points, p => new Point(p.x * 2, p.y * 2));
    Print("Scale by 2: ", result);
    
    //-- Rotate it by 45 degrees relative to the origin
    double angle = 45 * Math.PI / 180; // angle in radiants
    double sin = Math.Sin(angle);
    double cos = Math.Cos(angle);
    result = Transform(points, p => new Point(p.x * cos + p.y * sin, p.y * cos - p.x * sin));
    Print("Rotate by 45 degrees: ", result);
  }
}