boolean hover = false;
boolean locked = false;
float difx = 0.0;
float dify = 0.0;

void setup() {
  size(300, 300);
  ellipseMode(CENTER);
  particles = new ArrayList();
  smooth();
  Dist = (50);
}

void draw() {
  background(255);
  for (int i=0; i<particles.size(); i++) {
    Particle p = (Particle) particles.get(i);
    //p.run();
    //p.gravity();
    //p.move();
    p.display();
  }
  for (int i=particles.size()-1; i>=0; i--) {   
    Particle p1 = (Particle) particles.get(i);
    for (int j=0; j < particles.size(); j++) {     
      Particle p2 = (Particle) particles.get(j);     
      if (dist(p1.x, p1.y, p2.x, p2.y) < Dist) {       
        line(p1.x, p1.y, p2.x, p2.y);
      }
    }
  }
  for (int i=particles.size()-1; i>=0; i--) {   
    Particle p1 = (Particle) particles.get(i);
    if (mouseX > p1.x-10 && mouseX < p1.x+10 && mouseY > p1.y-10 && mouseY < p1.y+10) {   // MOUSE OVER
      hover = true;                                          
      if(!locked);
    }                                                 
    else {                                                                  
      hover = false;
    }
  }
}

/*
  if (particles.size() > 100) {
 particles.remove(0);
 } */

void mousePressed() {
  if (mouseButton == RIGHT)
    particles.add(new Particle());
  for (int i=particles.size()-1; i>=0; i--) {   
    Particle p1 = (Particle) particles.get(i);
    if(hover) {
      locked = true;
      fill(255);
    }
    else {
      locked = false;
    }
    difx = mouseX-p1.x;
    dify = mouseY-p1.y;
  }
}

void mouseDragged() {
  if (mouseButton == LEFT)
  for (int i=particles.size()-1; i>=0; i--) {   
    Particle p1 = (Particle) particles.get(i);
    if(locked) {
      p1.x = mouseX-difx;
      p1.y = mouseY-dify;
    }
  }
}

  void mouseReleased() {
    locked = false;
  }

  void keyPressed() {
    switch(key) {
    case '=':
      Dist+=20;
      break;
    case '-':
      Dist-=20;
      break;
    }
  }

 

  //////////////////////////////////// || CLASS

  // A simple Particle Class
  class Particle {
    float x;
    float y;
    float xspeed;
    float yspeed;

    Particle() {
      x = mouseX;
      y = mouseY;
      xspeed = random(-1,1);
      yspeed = random(-2,0);
    }
   
  void run() {
     x = x + xspeed;
     y = y + yspeed;
     }

    void gravity() {
      yspeed += 0.1;
    }

    void move() {
      y = y + yspeed;
      if (y > height) {
        yspeed = yspeed * -0.55;
        y = height;
      }
    }

    void display() {
      stroke(0);
      fill (0, 75);
      ellipseMode(CENTER);
      ellipse(x, y, 10, 10);
    }
  }