SineWave wave;

void setup(){
  size(500,300);
  stroke(255);//set color for point
  wave = new SineWave();
}

void draw(){
  background(0);
  wave.move();
}

class SineWave{
  int i = 0; // increment to create wave effect
  int _x = 0; // x position of drawn object
  float _y; // y position of drawn object
  int _width = 10; // width of object
  int _height = 10; // height of object
  int speed = 4; // speed of object
  boolean metLimit = false; // determines whether or not the object has reached the edge of the applet
  //constructor
  SineWave(){}
  void move(){
    _y=(sin(i*.4))*20+(height/2);//y position is sine function(which gives a value from -1 to 1)*20 for more effect + (half of height to center)
    _x+=setX();//add the x position of point
    ellipse(_x, _y, _width, _height); // set position of point
    i++; // increment variable i
  }

  int setX(){
    if(_x>=width && metLimit==false){
      metLimit = true;
      speed*=-1; // send left
    }else if(_x <= 0 && metLimit == true){
      metLimit = false;
      speed*=-1; // send left
    }
    return speed;
  }
}