// Dynamic Acceleration: PVector
// Daniel Shiffman <http://www.shiffman.net>
// The Nature of Code, Spring 2009

// Demonstrates a dynamically changing acceleration (towards the mouse)

// Declare a "Thing" object
Thing[] t;
int z = 0;
int timer = 0;
int rand = 1;
int k = 0;
  PVector a ;
  PVector v ;
  PVector l ;
  PVector prev = new PVector(0,0);
    int mouseTrack = 0;
  int[] prevMo = new int[4];
  
void setup() {
  size(700,400);
  smooth();
    t = new Thing[200];
  // Create the thing object




}

void draw() {
      prevMo[mouseTrack] = mouseX;
    mouseTrack++;
    prevMo[mouseTrack] = mouseY;
    mouseTrack++;
    if (mouseTrack == 4){
      mouseTrack = 0; 
    }
  background(0);
   a = new PVector(0.0,random(0,0.1));
 v = new PVector(0.0,0.0);
 l = new PVector(random(0,width),0-10);
    t[z] = new Thing(a,v,l);
for(int i = 0; i<z; i++){ 
  // Run the Thing object

  t[i].go();


    // Compute difference vector between mouse and object location
    // 3 steps -- (1) Get Mouse Location, (2) Get Difference Vector, (3) Normalize difference vector


  
    PVector m = new PVector(prevMo[2],prevMo[3]);
    prev = new PVector(prevMo[0], prevMo[1]);
PVector diffMo = PVector.sub(prev,m);
PVector zero = new PVector(0,0);

if(diffMo.x != zero.x && diffMo.y != zero.y){
  
    PVector diff = PVector.sub(m,t[i].getLoc());

    float factor = -1.5;  // Magnitude of Acceleration (not increasing it right now)
    
          diff.normalize();
    diff.mult(factor);
    //object accelerates towards mouse
    t[i].setAcc(diff);
    println(diffMo);
}

}



   if ( rand == 1){
    rand = 0;
    timer = int(random(10,15));
    if(z<199){
     // println(z+"z");
      z++;
    }
  }
  k++;
    if(k==timer){
    rand=1;
    k=0;
  }

}

// Renders a vector object 'v' as an arrow and a location 'loc'
void drawVector(PVector v, PVector loc, float scayl) {
  pushMatrix();
  float arrowsize = 4;
  // Translate to location to render vector
  translate(loc.x,loc.y);
  stroke(0);
  // Call vector heading function to get direction (note that pointing up is a heading of 0) and rotate
  rotate(v.heading2D());
  // Calculate length of vector & scale it to be bigger or smaller if necessary
  float len = v.mag()*scayl;
  // Draw three lines to make an arrow (draw pointing up since we've rotate to the proper direction)
  line(0,0,len,0);
  line(len,0,len-arrowsize,+arrowsize/2);
  line(len,0,len-arrowsize,-arrowsize/2);
  popMatrix();
}