// flocks of birds

float x, y, w, h;
int n;

void setup () {
  // setup //
  size( 650,450);
  reset();
}
void reset () {
  // reset
  n= int ( random(5,10) );
  x= random(width/2);
  y= random(height/2);
  w= random(10,70);
  h= w/3;
}
void draw() {
  // next frame//
  background( 200,250,200);
  fill( 255,255, 0);
   flock( n, x,y, w,h );
  x += random(30);
  y= y +10 - random(20);
}

void flock( int n, float x, float y, float w, float h ) {
  // draw a flock of n birds//
  // draw first bird//
  float xx= x;
  float hh= h * 4;
  float ww= w;
  bird( xx,y,w,h);
  // now draw pairs, behind this pair.
  xx= xx-2*w;
  for (int j=1; j<n; j++ ) {
    // draw next pair of birds. //
    bird( xx,y-hh, w,h );            // up
    bird( xx,y+hh, w,h );               // down
    xx= xx- xx - 2*w;            // next pair behind this paiir
    ww *= 0.9;                      // smaller
    hh = hh + h*3;
  }
 
}
void bird( float x, float y, float w, float h ) {
  //// draw a bird
  triangle( x, y, x-w, y-h, x-w, y+h );
}
void keyPressed() {
  // keys
  if (key == 'r') reset();
}