int n; //# of bird pairs
float x, y; //position
float w , h; //bird size
float horizon=500;
String myName = "Adam Kochen";
String gName = "Flock";

void setup () {
size(800,600);
reset();
}

void draw() {
  background(200,250,255); //sky
 //0-0 x = 600;
 //0-0 y = 300;
 //0-0 if(x-60*n < width){
   x += random(20);
  //0-0 }

 y = y-random(1,5)+random(1,5);
  w= 30;
  h= 20;
  flock(n,x,y,w,h);
  if(x-60*n > width){
    reset();
  }
  
  //test text
  fill(0);
  text("n "+n,10,10);
  text("x "+x,10,20);
  text("y "+y,10,30);
  text("w "+w,10,40);
  text("h "+h,10,50);
  text(myName + " - " + gName,300,10);
}


void bird(float x,float y,float w,float h )
{ 
  //draw lead bird triangle
  triangle(x,y,x-w,y-h/2,x-w,y+h/2);
}
void flock(int n,float x,float y,float w,float h){
  //followers
  float xx = x; 
  float yy = y; 
  float dy = w/200;
  float dx = h/5 ;
  float ww = w;
  float hh = h;
 
  for( int l = 1; l < n ; l++){
    bird( xx,y-dy, ww,hh );      // above
    bird( xx,y+dy, ww,hh );     // below
      // shrink bird        
      hh *= 0.9;           
      ww *= 0.95;
      //birds above and below
      xx=  xx - 2*w;
      dy = dy + h;
  }
}

void reset() {
  // reset
  n = int (random(4,7));
  x=  random(0,50);
  y=  random(0,horizon);
  w=  50;
  h=  20;
}

void keyPressed() {
  // keys
  if (key == 'r') reset();
}