class Bar{
  ArrayList rectVertex;
  float w = 10;
  color c = color(0,200,0,200);
  
  Bar(){
    rectVertex = new ArrayList();
  }
  
  void addRect(float x,float y,float z,float px,float py,float pz){
    this.rectVertex.add(new Rectangle(x,y,z,px,py,pz));
    if(rectVertex.size() > 500){
      rectVertex.remove(0);
    }
  }
  
  void draw(){
    int len = rectVertex.size();
    for(int i = 0;i < len;i++ ){
      Rectangle rec = (Rectangle)rectVertex.get(i);
      rec.draw();
    }
  }
}

class Rectangle{
  PVector pos;
  PVector ppos;
  float w = 10;
  color c = color(random(255),random(255),random(255),random(255));
  
  Rectangle(float x,float y,float z,float px,float py,float pz){
    this.pos = new PVector(x,y,z);
    this.ppos = new PVector(px,py,pz);
  }
  
  void draw(){
    stroke(0);
    fill(this.c);
    beginShape();       
    vertex(this.pos.x,this.pos.y-this.w,this.pos.z);
    vertex(this.pos.x,this.pos.y+this.w,this.pos.z);
    vertex(this.ppos.x,this.ppos.y+this.w,this.ppos.z);
    vertex(this.ppos.x,this.ppos.y-this.w,this.ppos.z);
    endShape(CLOSE);
  }
}

float u;
float v;

float vu = 0.;
float vv = 0.;

float au = 0.;
float av = 0.;

float px;
float py;
float pz;

boolean firstDraw = true;

Bar l;

void setup(){
  size(450,450,P3D);
  background(255);
  
  l = new Bar();

}

void draw(){
  background(255,30);
  
  vu += au;
  vv += av;
  
  u += vu;
  v += vv;
  
  au *= 0.96;
  av *= 0.96;
  
  vu *= 0.92;
  vv *= 0.92;
  
  translate(width/2,height/2);
  
  rotateY(v);
  rotateX(u);
  
  l.draw();
}

void mouseDragged(){
  float x = (mouseX-width/2)*cos(v);
  float y = (mouseX-width/2)*sin(u)*sin(v)+(mouseY-height/2)*cos(u);
  float z = (mouseX-width/2)*cos(u)*sin(v)-(mouseY-height/2)*sin(u);
  if(firstDraw){
    firstDraw = false;
  }
  else{
    l.addRect(px,py,pz,x,y,z);
  }
  px = x;
  py = y;
  pz = z;
}

void keyPressed(){
  if(keyCode == UP){
    au += PI/200.;
  }
  if(keyCode == RIGHT){
    av += PI/200.;
  }
  if(keyCode == DOWN){
    au -= PI/200.;
  }
  if(keyCode == LEFT){
    av -= PI/200.;
  }
}