class Parti {
  
//VARIABLES
  float x;
  float y;
  float xspeed = random(1,3);
  float yspeed = random(1,3);
  color particlec;
  float r = 8;
  
//CONSTRUCTOR

Parti(float _x, float _y, color _particlec){
  x = _x;
  y = _y;
  particlec = _particlec;
}

//Random Walk
void move() {
  int xstep = int(random(0,3))-1; //random walk for x
  int ystep = int (random(0,3))-1; //random walk for y
  x += xstep*xspeed; // acceleration
  y += ystep*yspeed;
  
//bounce back
  if ((x > width) || (x < 0)) {
    xspeed = xspeed * -1;
  } 
  if ((y > height) || (y < 0)) {
    yspeed = yspeed * -1;
  }
}

//draw particles
void display(){
  noStroke();
  fill(particlec);
  ellipse (x,y, r, r);
}

//run all function
void run(){
  display();
  move();
}
}

//---------------------LIBRARIES

//---------------------GLOBAL VARIABLES
int particlesSize = 1000;
int particlesSize2 = 100;
color c = color(3,180,255,200); //initil particles (blue)
color c2 = color(255,150,20,200); // seondary particles (orange)

//---------------------DECLARE OBJECT
ArrayList particles; 

//---------------------SETUP LOOP
void setup(){
size (1000,400);
smooth();
frameRate(30);
background (0);

//-------------------INITIALIZE OBJECT
particles = new ArrayList (); //start with empty list
for (int i = 0; i< particlesSize; i ++) {
  Parti myParti = new Parti(random(0,width),random(0,height),c);
  particles.add(myParti);
  }
}

//---------------------DRAW LOOP
void draw(){
  fill (0,10); // particles fade out
  rect (0,0,width,height);
  for (int i = 0; i < particles.size(); i ++) {
    Parti p = (Parti) particles.get(i);
    p.run();
  }
  if(mousePressed){// add secondary particles
    for (int i = 0; i< particlesSize2; i ++) {
    particles.add(new Parti(random(0,width),random(0,height),c2));
  
  }
}
}

//---------------------ADDITIONAL FUNCTION
void keyPressed(){
  saveFrame();
}