public class particle {
  PVector position;
  PVector velocity;
  PVector angle;
  PVector angularVelocity;
  float radius;
  float life;
  boolean alive;

  public particle() {
    position=new PVector();
    velocity=new PVector();
    life=0;
    angle=new PVector();
    angularVelocity=new PVector();
    alive=false;
  }

  public particle(PVector position) {
    this.position=position;
    velocity=new PVector();
    radius=(float) random(3,10);
    life=(int) random(10,1000);
    angle=new PVector();
    angularVelocity=new PVector((float) random(0,0.05),(float) random(0,0.05),(float) random(0,0.05));
    alive=true;
  }

  public particle(PVector position, PVector velocity) {
    this.position=position;
    this.velocity=velocity;
    radius=(float) random(3,10);
    life=(int) random(10,1000);
    angle=new PVector();
    angularVelocity=new PVector((float) random(0,0.05),(float) random(0,0.05),(float) random(0,0.05));
    alive=true;
  }

  public void move() {
    position=PVector.add(position,velocity);
    angle=PVector.add(angularVelocity,angle);
    life--;
    if(life<0)
      life=0;
  }
  public void plot() {
    pushMatrix();
    translate(position.x,position.y,position.z);
      pushMatrix();
      rotateX(angle.x);
        pushMatrix();
          rotateY(angle.y);
          pushMatrix();
            rotateZ(angle.z);
            box(radius);
          popMatrix();
        popMatrix();
      popMatrix();
    popMatrix();
  }
}

float rotX=0,rotY=0;
float a=0;
float b=0;
ArrayList<particle> particles;
void setup() {
  size(800,600,P3D);
  particles=new ArrayList<particle>();
  for(int i=0;i<(int) random(100,1000);i++) {
    float r=width/12;
    float theta=(float) random(0,TWO_PI);
    float phi=(float) random(0,PI);
    PVector p=new PVector(r*sin(theta)*sin(phi),r*cos(theta)*sin(phi),r*cos(phi));
    PVector v=PVector.mult(p,1/p.mag());
    v.mult((float) random(1,2));
    particles.add(new particle(p,v));
  }
}
void mouseDragged() {
  rotX+=(mouseX-pmouseX)*0.01;
  rotY-=(mouseY-pmouseY)*0.01;
}
void draw() {
  background(0);
  directionalLight(255,0,0,0,1,0);
  directionalLight(255,255,0,-1,0,0);
  directionalLight(255,0,0,0,-1,0);
  directionalLight(0,255,0,1,0,0);
  translate(width/2,height/2,0);
  rotateX(rotY);
  rotateY(rotX);
  pushMatrix();
  rotateZ(b);
  pushMatrix();
  rotateY(a);
  noFill();
  stroke(255);
  box(width/4);
  fill(255,150);
  noStroke();
  for(int i=0;i<particles.size();i++) {
    if(particles.get(i).alive)
      particles.get(i).plot();
  }
  for(int i=0;i<particles.size();i++) {
    particles.get(i).move();
    if(particles.get(i).position.mag()>width/3) {
      float r=(float) random(10,width/12);
      float theta=(float) random(0,TWO_PI);
      float phi=(float) random(0,PI);
      PVector p=new PVector(r*sin(theta)*sin(phi),r*cos(theta)*sin(phi),r*cos(phi));
      PVector v=PVector.mult(p,1/p.mag());
      v.mult((float) random(1,2));
      particles.get(i).position=p;
      particles.get(i).velocity=v;
      particles.get(i).life=(float) random(10,1000);
      particles.get(i).alive=true;
    }
  }
  popMatrix();
  popMatrix();
  a+=0.01;
  b+=0.01;
}