// 5 juillet 2010 / emoc / http://codelab.fr/1774

ArrayList tendrils;
float ang = 0;

void setup() {
  size(400,400);
  frameRate(30);
  smooth();
  tendrils = new ArrayList();
}

void draw() {
  background(255);
  ang += random(-60, 60);
  tendrils.add( new Tendril(width / 2, height / 2));
  
  if (tendrils.size() > 50) tendrils.remove(0);
  
  for (int i = 0; i < tendrils.size(); i++) {
     Tendril t = (Tendril) tendrils.get(i);
     t.update(ang);
     t.ink();
  }
}

/* ****************************** */

class Tendril {
  
  PVector pos;
  float col = 0;
  
  Tendril(float _x, float _y) {
    pos = new PVector(_x, _y);
  }

  void update(float ang) {
    col = (col + 3)%255;
    pos.set(pos.x + 3 * cos(radians(ang)), pos.y + 3 * sin(radians(ang)), 0);
  }
  
  void ink() {
    colorMode(HSB);
    fill(col,255,240); noStroke();
    ellipse(pos.x, pos.y, 3, 3);
  }
}

float pi = 3.1415;
int w = 800; 

float x = 0;
float y = 0;
float vx = 0;
float vy = 0;
float ax = 0;
float ay = 0;

float dt=1;

void setup(){ 

  size(w,w); 
  smooth(); 
  
} 

void draw(){ 
  

  fill(250, 2);
  rectMode(CORNER);
  rect(0,0,width,height);
  
  ax = ax + dt*( 1*random(-1,1) - 0.05*ax);
  ay = ay + dt*( 1*random(-1,1) - 0.05*ay);
  
  vx =  vx + dt*(2*ax - 0.05*vx);
  vy =  vy + dt*(2*ay - 0.05*vy);

  x =  x + 0.05*dt*vx;
  y =  y + 0.05*dt*vy;
  
  fill(0);
  ellipse(x + width/2.0, y+height/2.0, 5, 5);

} 

void mouseReleased() {
  
  x =  0;
  y =  0;
  vx =  0;
  vy =  0;
  ax =  0;
  ay =  0;
  
}