int i=0;//variable to increment
void setup(){
  size(500,300);
}
void draw(){
  background(0);
  float xPos=sin(i*.4)*50;
  xPos +=i;
  if (i>=width+10){
    i=(-10);
  }
  //println(i);
  float yPos=(cos(i*.4))*50+(height/2);//y position is sine function(which gives a value from -1 to 1)*20 for more effect + (half of height to center)
  ellipse(xPos, yPos,10,10);// set position of point
  i++;//increment variable i
}