// AnimSine.java
// Slightly reformatted by Andrew Davison, Nov. 2022

// https://stackoverflow.com/questions/37648830/making-a-sine-graph-move

/* Animate a sine wave.

   Usage:
     >  compile AnimSine.java
     > run AnimSine
*/

import java.awt.Color;


public class AnimSine 
{
  private static int RADIUS = 100;

  public static void main(String[] args)  
  {
    StdDraw.setXscale(0, 900);
    StdDraw.setYscale(0, 700);
    StdDraw.enableDoubleBuffering();

    double offset = 0;

    while (true) {
      StdDraw.show();
      StdDraw.pause(20);
      StdDraw.clear();

      offset -= 5;  // was 1

      StdDraw.setPenColor(StdDraw.BLACK);
      StdDraw.line(0, 350, 900, 350); // x-axis
      StdDraw.line(450, 0, 450, 900); // y-axis
      StdDraw.setPenColor(StdDraw.RED);

      double prevX = 0;
      double prevY = 50 * Math.sin((prevX + offset) * (Math.PI / 180)); // seed the previous Y to start

      StdDraw.filledCircle(450 + prevX, 350 - prevY, 5);

      for (double x = 0; x <= 450; x += 3) {
        double y = 50 * Math.sin((x + offset) * (Math.PI / 180));
        StdDraw.line(450 + (int) prevX, 350 - (int) prevY, 
                     450 + (int) x, 350 - (int) y);
        prevX = x;
        prevY = y;
      }

    }
  }

}  // end of AnimSine