class ALPHA_PLUS{
  
  PVector pos, V, A;
  PVector [] trails;
  float Theta, a;
  byte trailsPointer;
  
  ALPHA_PLUS(PVector posTEMP, PVector VTEMP){
    
    pos = posTEMP;
    
    trails = new PVector [127];
    for (int i=0; i<trails.length; i++){
      trails[i] = new PVector(pos.x,pos.y);
    }
    trailsPointer = 0;
    
    V = VTEMP;
  }
  
  void move(){
    a = 1000/sq(dist(pos.x,pos.y,width/2,height/2));
    Theta = atan2(pos.y-height/2,pos.x-width/2);
    
    A = new PVector(a*cos(Theta),a*sin(Theta));
    
    V.add(A);
    pos.add(V);
    
    trails[trailsPointer] = new PVector(pos.x,pos.y);
    trailsPointer ++;
    if (trailsPointer==trails.length){
      trailsPointer=0;
    }
  }
  
  void display(){
    noStroke();
    fill(0,255,0);
    ellipse(pos.x,pos.y,10,10);
  }
  
  void show_trails(){
    for (int i=0; i<trails.length; i++){
      stroke(255);
      point(trails[i].x,trails[i].y);
    }
  }
}