スピンする立方体

/**
* spinning cubes
*
* @author aa_debdeb
* @date 2016/09/12
*/

ArrayList<Box> boxes = new ArrayList<Box>();

void setup(){
  size(640, 640, P3D);
  noStroke();
  boxes = new ArrayList<Box>();
  
  while(boxes.size() < 50){
    PVector loc = new PVector(random(width), random(height), random(0, -500)); 
    float size = random(20, 50);
    boolean isOverlapped = false;
    for(Box box: boxes){
      if(PVector.dist(loc, box.loc) < sqrt(sq(size) + sq(size * sqrt(2))) / 2 + sqrt(sq(box.size) + sq(box.size * sqrt(2))) / 2){
        isOverlapped = true;
        break;
      }
    }
    if(!isOverlapped){
      boxes.add(new Box(loc, size));
    }
  }
}

void draw(){
  background(0);
  lights();
  for(Box box: boxes){
    box.display();
    box.update();
  }
}

class Box{

  PVector loc, ang, vel;
  float size;
  color c;
  
  Box(PVector _loc, float _size){
    loc = _loc;
    size = _size;
    ang = new PVector(random(TWO_PI), random(TWO_PI), random(TWO_PI));
    setRandomVel();
    if(random(1) < 0.5){
      c = color(50, 205, 50);
    } else {
      c = color(204, 49, 126);
    }
  }
  
  void setRandomVel(){
    float x = (random(1) < 0.5 ? 1: - 1) * random(PI / 32, PI / 16);
    float y = (random(1) < 0.5 ? 1: - 1) * random(PI / 32, PI / 16);
    float z = (random(1) < 0.5 ? 1: - 1) * random(PI / 32, PI / 16);
    vel = new PVector(x, y, z);
  }
  
  void update(){
    vel.mult(0.99);
    if(random(1) < 0.001){
      setRandomVel();
    }
    ang.add(vel);
  }
  
  void display(){
    fill(c);
    pushMatrix();
    translate(loc.x, loc.y, loc.z);
    rotateX(ang.x);
    rotateY(ang.y);
    rotateZ(ang.z);
    box(size);
    popMatrix();
  }
  
}