// zigzag static
int a,f;

void setup(){
  size(320,240);
  noFill();
}

void draw(){
  for(int x=0; x<width; x+=3){
    a = 3;
    f = 20;
    beginShape();
    for(int y=0; y<=height; y+=f){
      vertex(x+a,y);
      a = 0-a;
    }
    endShape();
  }
}