//import processing.opengl.*; //use opengl for faster rendering
int unit = 40;
int num;
Foo[] mods;
int size = 400;
boolean bg;

void setup() 
{
    //size(size, size, OPENGL); //use opengl for faster rendering
    size(400, 400); // to make an applet happy
  //noStroke();
  frameRate(50);
  smooth();
  num = 50;
  mods = new Foo[num];
  reset();

}

void reset() {
  for(int i=0; i<mods.length; i++) {
    mods[i] = new Foo();
  }
  background(#FFFFFF);
}

void draw() 
{
  if (bg) background(#FFFFFF);
  for(int i=0; i<mods.length; i++) {
    mods[i].update();
    mods[i].draw();
  }
}

void mousePressed() {
  if (mouseButton== RIGHT)
    bg=!bg;
  else
    reset();
}


class Foo {
  float[] pos= new float[2];
  float[] vel = new float[2];;
  float[] acc = new float[2];;
  float[] col =  new float[3] ;
  float[] dCol = new float[3];
  float dMin = .1f;
  float dMax = 5f;
  float mass;
  int age = 0;
  int maxAge = 100;
  Foo() {
    init();
  }

  void init() {
    pos[0] = mouseX;
    pos[1] = mouseY;
    age=(int)random(maxAge/2);
//     pos[0] = random(0,size);
//     pos[1] = random(0,size);


    mass = random(5,15);
    for( int i = 0; i < col.length; i++) {
      col[i] = colRand();
      dCol[i] = dRand();
    }

    do {
      for( int i = 0; i < vel.length; i++) {
	vel[i] = random(-dMax, dMax);
	acc[i] = .0001 * random(-dMax, dMax);
      }
    } while(!alive());
  }

  float dRand() {
    return random(dMin,dMax);
  }

  float colRand() {
    return random (0,255);
  }

  void update() {
    age++;
    //gravity
    acc[1] += gravity;
    addAcceleratedSpeed();
    addSpeed(col, dCol, 255);
    if (!alive())
      init();
  }
  float tolerance = .01;
  boolean alive () {
    boolean alive = age<maxAge;
    int idx = 0;
  //   while(alive && idx<2) {
//             alive = abs(acc[idx])>tolerance || abs(vel[idx])>tolerance;
//       //      alive = (size-pos[1])>30;// && abs(acc[idx])>gravity;

//       idx++;
//     }
    return alive;
  }

  float friction = .9998;
  float gravity = .001;
  float elastic = .7;
  int max = size;
  void addAcceleratedSpeed() {
    for( int i = 0; i < pos.length; i++) {
      vel[i] *=friction;
      float tmpVel = vel[i] +  acc[i];
      float tmp = pos[i] + tmpVel;
      boolean collision = false;
      if (tmp>= max || tmp<0) 
	collision = true;

      if (collision) {
	vel[i] *= -elastic ;
	acc[i] *=elastic;
	tmpVel = vel[i] +  acc[i];
	tmp = pos[i] + tmpVel;
      }
      vel[i] = tmpVel;
      pos[i] = tmp;
    }
  }

  void addSpeed(float[] pos, float[] vel, int max) {
    for( int i = 0; i < pos.length; i++) {
      float tmp = pos[i] + vel[i];
      if (tmp> max) {
	vel[i] = -dRand();
	pos[i] += vel[i];
      } else if (tmp<0) {
	vel[i] = dRand();
	pos[i] += vel[i];
      } else {
	pos[i] = tmp;
      }
    }
  }


  void move() {

  }
  
  void draw() {
    ellipseMode(CENTER);
    float x = mass, y=mass;
    if (pos[0] + mass>size) {
      x = pos[0]-size;
    } else if (pos[0] - mass<0) {
      x = 0-pos[0];
    }

    if (pos[1] + mass>size) {
      y = pos[1]-size;
    } else if (pos[1] - mass<0) {
      y = 0-pos[1];
    }

    ellipse(pos[0], pos[1], x , y); 
    fill(col[0], col[1], col[2]);
  }

}