// Attraction
// Daniel Shiffman <http://www.shiffman.net>

// A class to describe a thing in our world, has vectors for location, velocity, and acceleration
// Also includes scalar values for mass, maximum velocity, and elasticity

class Thing {
  Vector3D loc;
  Vector3D vel;
  Vector3D acc;
  float mass;
  float max_vel;
  float bounce = 5.0f; // How "elastic" is the object
  float G;             // Universal gravitational constant
  float timer;
  boolean eating = false;
  boolean ate = false;
  boolean dead = false;
  float nw;
  float nh;

  Thing(Vector3D a, Vector3D v, Vector3D l, float m_) {
    acc = a.copy();
    vel = v.copy();
    loc = l.copy();
    mass = m_;
    max_vel = 5.0f;
    G = 0.9f;
    timer = 0;
    nw = mass + mass;
    nh = mass + mass/6;

  }

  Vector3D getLoc() {
    return loc;
  }

  Vector3D getVel() {
    return vel;
  }
  float getMass() {
    return mass;
  }

  float getX(){
    return loc.x;
  }

  float getY(){
    return loc.y;
  }

  void addMass(float foodMass){
    mass += foodMass;
    max_vel += foodMass/50;
    nw = mass + mass;
    nh = mass + mass/6;

  }

  Vector3D calcGravForce(Thing t) {
    Vector3D dir = Vector3D.sub(t.getLoc(), loc);     // Calculate direction of force
    float d = dir.magnitude();                        // Distance between objects
    d = constrain(d,200.0f,100.0f);                      // Limiting the distance to eliminate "extreme" results for very close or very far objects
    dir.normalize();                                  // Normalize vector (distance doesn't matter here, we just want this vector for direction)
    float force = (G * mass * t.getMass()) / (d * d); // Calculate gravitional force magnitude
    dir.mult(force);                                  // Get force vector --> magnitude * direction
    return dir;
  }

  Vector3D calcRepForce(Thing t) {
    Vector3D dir = Vector3D.sub(loc, t.getLoc());     // Calculate direction of force
    float d = dir.magnitude();                        // Distance between objects
    d = constrain(d,300.0f,100.0f);                      // Limiting the distance to eliminate "extreme" results for very close or very far objects
    dir.normalize();                                  // Normalize vector (distance doesn't matter here, we just want this vector for direction)
    float force = (G * mass * t.getMass()) / (d * d); // Calculate gravitional force magnitude
    dir.mult(force);                                  // Get force vector --> magnitude * direction
    return dir;
  }

  void add_force(Vector3D force) {
    force.div(mass);
    acc.add(force);
    if (showVectors) {
      drawVector(force,loc,1000);
    }    
  }

  void setAcc(Vector3D v) {
    acc = v.copy();
  }
  // Main method to operate object
  void go() {
    update();
    render();
  }

  void stop() {
    px = loc.x;
    py = loc.y;
    vel.add(new Vector3D(0,0,0));
    vel.limit(0);
    loc.add(new Vector3D(0,0,0));
    acc.setXYZ(0.0,0.0,0.0);
  }

  // Method to update location
  void update() {
    if (dead){
      stop();
    }
    else{
      px = loc.x;
      py = loc.y;
      vel.add(acc);
      vel.limit(max_vel);
      loc.add(vel);
      acc.setXYZ(0.0,0.0,0.0);
    }
  }

  // Method to display
  void render() {
    ellipseMode(CENTER);
    noStroke();

    xoff += 0.5;
    yoff += 0.5;

    nw = mass + mass;
    nh = mass + mass/6;

    noStroke();

    //fill(random(0,50),random(0,50),random(150,255));     
    if (dead){
      nw = mass;
      nh = mass;
      fill(50,50,100);
      ellipse(loc.x,loc.y,nw,nh);
      fill(255);
      ellipse(loc.x+nw/2, loc.y,noise(xoff) * nw/3 + nw/3,noise(yoff) * nh/4 + nh/4);
      eating = false;
      ate = false;
    }
    else{

      fill(noise(xoff)*20+50,noise(xoff)*20+50,noise(xoff)*100+200);
      ellipse(loc.x,loc.y,nw,nh);

      //fill(random(0,150),random(100,250),random(200,255));     
      fill(noise(xoff)*20+150,noise(xoff)*50+175,noise(xoff)*20+225);

      if(loc.x < px){
        ellipse(loc.x+nw/2, loc.y,noise(xoff) * nw/3 + nw/3,noise(yoff) * nh/4 + nh/4);
      }
      else{
        ellipse(loc.x-nw/2, loc.y,noise(xoff) * nw/3 + nw/3,noise(yoff) * nh/4 + nh/4);
      }

      if(eating){
        nw = mass + mass;
        nh = mass + mass/6;

        //println("eating");
        //fill(200,10,10);
        stroke(0,200,200);
        strokeWeight(3); 
        noFill();
        ellipse(loc.x,loc.y,nw,nh);
        if (timer%10 == 0){
          ate = true;
          eating = false;
        }
      }


      eating = false;
      ate = false;
    }
    timer++;
  }

  void eating() {
    eating = true;
  }

  boolean ate(){
    return ate;
  }

  void die(){
    dead = true;
  }

  boolean dead(){
    return dead;
  }

  float getW(){
    nw = mass + mass;
    return nw;
  }
  float getH(){
    nh = mass + mass/6;
    return nh;
  }
}