//
ArrayList<Thing> things;
float particlesPerFirework = 300;

//Add a bunch of things and "place them" somewhere
void populateThings()
{
  things = new ArrayList<Thing>();


  //start in the midle position
  float x = width/2;
  float y = height/2;

  //Use mouse position for x and y.
  x = mouseX;
  y = mouseY;

  float numberOfParticles = particlesPerFirework;
  float theHue = random(100);
  for (int i=0; i<numberOfParticles; i+=1)
  {
    //x = i*(width/numberOfParticles);
    //float dy = noise(i)*100;
    Thing aThing = new Thing(x, y);
    aThing.hue = theHue;
    things.add(aThing);
  }
}



class Thing
{
  float x;
  float y;

  float vx;
  float vy;

  float size;
  float hue;
  float opacity;

  Thing(float x, float y)
  {
    this.x = x;
    this.y = y;
    opacity = 1;
    size = 4;
    hue = random(100);//random hue


    float angle = random(360);
    float speed = random(8);
    vx = (float) speed*cos(angle);
    vy = (float) speed*sin(angle);
    //vx = randomGaussian() * 5;
    //vy = randomGaussian() * 5;
  }

  //Draws the "thing"
  void drawMe()
  {
    fill(hue, 100, 100, 255*opacity);
    ellipse(x, y, size, size);
    //System.out.println("Drawing at "+x+" "+" "+y);
  }

  void fall()
  {
    vy += .1;
  }

  void slower(float resist)
  {
    vx = vx*(1 - resist);
    vy = vy*(1 - resist);
    opacity = opacity*(1 - resist);
  }
  void moveByVel()
  {
    x += vx;
    y += vy;
  }

  //brings to the top, but only sometimes.
  void maybeJump()
  {
    if (random(1000) < 1)
      y = 0;
  }
}

void draw() {
  if (things == null) //Stop if there are no things
    return;
  for (Thing thing: things)
  {
    thing.drawMe();
    thing.moveByVel();
    thing.slower(.03);
    //thing.fall();
    if (thing.y > height)
    {
      thing.vy = thing.vy*(-1);
    }
    //if(thing.y > -10+height)
    //  thing.maybeJump();
    //    p.run();
    //    if (p.isDead()) {
    //      it.remove();
  }
}

void mouseClicked()
{
  background(0); // clear screen
  populateThings(); //start over
}

void setup() {
  size(640, 360);
  colorMode(HSB, 100);
  //populateThings();
}