// A simple Particle class

class Particle {
  Vector3D loc;
  Vector3D vel;
  Vector3D acc;

  float  startRadius=10;
  float r;
  float timer;
  color _c;
  color startColor;
  public int lifeTime=220;
  float clearValue=12;
  int redDec;
  int blueDec;
  int greenDec;

  
  // Another constructor (the one we are using here)
  Particle(Vector3D l, color c, int d, float a) {
    lifeTime=d;
    acc = new Vector3D(random(-.1*a,.1*a),random(-.05*a,.05*a),0 );  //This determines how fast it falls or shoots out  
    float seed=random(-4,1);
    vel = new Vector3D(cos(seed),sin(seed),0);  //This determines what direction it initially spreads in
    loc = l.copy();
    startRadius = random (2,maxRadius);
    timer = lifeTime;
    _c=c;
    startColor=_c;
  }


  void run() {
  
  
    
    //Color
    redDec=int((255-red(startColor)) * random(1,timer)/lifeTime)+redOffset;
    blueDec=int((255-blue(startColor)) * random(1,timer)/lifeTime)+blueOffset;
    greenDec=int((255-green(startColor)) * random(1,timer)/lifeTime)+greenOffset;
    
    //Greyscale
 //   redDec=int((255-red(startColor)) * random(1,timer));
 //   blueDec=int((255-blue(startColor)) * random(1,timer));
  //  greenDec=int((255-green(startColor)) * random(1,timer));

    
    r=startRadius*(timer/lifeTime);
    
    clearValue=10; 

    clear(); 
    update();
    render();

  }

  // Method to update location
  void update() {
    vel.add(acc);
    loc.add(vel);
    timer--;
  }

  //Clears previous render
  void clear() {
   if (clearTrail==false) return;
    noStroke();
    fill(0,clearValue);
    ellipse(loc.x,loc.y,r,r);
  }

  // Method to display
  void render() { 

    _c=color(red(startColor)+redDec,green(startColor)+greenDec,blue(startColor)+blueDec);
    stroke(0,10);
    ellipseMode(CENTER);
    fill(_c,timer/3);
    ellipse(loc.x,loc.y,r,r);
  }
  
  // Is the particle still useful?
  boolean dead() {
    if (timer <= 0.0) {
      return true;
    } else {
      return false;
    }
  }
}