//import processing.opengl.*;

int NUMACTORS = 15;
int i = 0;

int rNum1, rNum2;

Actor actors[] = new Actor[NUMACTORS];

void setup(){
  size(500,500,P3D);
  reset();
  ellipseMode(CENTER_RADIUS);
  background(0);
  //smooth();
}

void draw(){
  if(keyPressed){
    if(key == ' '){
      reset();
    }
    background(0);
  }
  for(i = 0; i < NUMACTORS; i++){
    actors[i].step();
  }
}

void reset(){
  for(i = 0; i < NUMACTORS; i++){
    actors[i] = new Actor(random(0,width), random(0,height), random(1,10), actors, NUMACTORS);
    //actors[i].attach((int)random(0,NUMACTORS-1) , (int)random(0,NUMACTORS-1));
    actors[i].attach((i+1)%NUMACTORS, (NUMACTORS-(i-1))%NUMACTORS);
  }
}
class Actor{
  float x,y,m;

  float rx,ry;
  float ax,ay;
  float fx,fy;

  Actor actors[];

  int follow;
  int avoid;
  int NUMACTORS;
  float FK = -2;
  float AK = .010;
  float DAMP = .3;
  int STEPS = 50;
  float POINTALPHA = 50;
  int POINTCOLOR = 255;
  float POINTRADIUS = 1.;

  Actor(float x, float y, float m, Actor[] actors, int NUMACTORS){
    this.x=x;
    this.y=y;
    this.m=m;
    this.actors = actors;
  }

  void attach(int follow, int avoid){
    this.follow = follow;
    this.avoid = avoid;
  }

  void step(){
    /*force = -k * (tempypos - rest_posy);  // f=-ky 
     accel = force / mass;             // Set the acceleration, f=ma == a=f/m 
     vely = damp * (vely + accel);     // Set the velocity 
     tempypos = tempypos + vely;               // Updated position 
     
     force = -k * (tempxpos - rest_posx);  // f=-ky 
     accel = force / mass;             // Set the acceleration, f=ma == a=f/m 
     velx = damp * (velx + accel);     // Set the velocity 
     tempxpos = tempxpos + velx;               // Updated position */

    //f = k*(distance to followed) - k*(distance to avoided)
    for(int i = 0; i<STEPS; i++){

      fx = (FK*(x-actors[follow].x));
      fy = (FK*(y-actors[follow].y));
      
      fx -= cos(atan2(actors[avoid].y-y,actors[avoid].x-x));
      fy -= sin(atan2(actors[avoid].y-y,actors[avoid].x-x));
      

      //f = m*a
      //a = f*(1/m)
      ax = fx/m ;
      ay = fy/m ;

      //r = a*t
      //r' = a
      rx = DAMP*(rx+ax);
      ry = DAMP*(ry+ay);

      //d = r*t
      //d' = r
      x += rx;
      y += ry;

      noStroke();//stroke(POINTCOLOR, POINTALPHA);
      fill(POINTCOLOR,POINTALPHA);
      ellipse(x,y,POINTRADIUS,POINTRADIUS);
    }
  }
}