// author: didier hilhorst
// p5_version: 0068

BImage b;
Particle[] party;

void setup() {
    rectMode(CENTER_DIAMETER);
    size(400,400);
    b = loadImage("part_bg.gif");
    party = new Particle[500];

    for (int i=0; i<party.length; i++) {
      party[i] = new Particle();
      party[i].vx = random(5);
      party[i].vy = random(5);
      party[i].sy = random(0, 340);
    }
}

void loop() {
  background(b);
  for (int i=0; i<party.length; i++) {
    party[i].update();
    party[i].render();
  }
}
  
class Particle {
  float sx, sy, vx, vy, r, g, b, a, size = 2;
  Particle (float x, float y) {
    sx = x;
    sy = y;
    r = 255;
    b = 255;
    g = 255;
  }
  
  Particle() {
    sx = int(random(width));
    sy = int(random(height));
  }
    
  
  void render() {
  
  if ((this.sy < 344)) {
  
    r = 255;
    g = 255;
    b = 255;
    a = int(random(20, 100));
    
    if ((abs(this.sx - mouseX) < 40) && (abs(this.sy - mouseY) < 40) && (mouseY < 344)) {
      this.sx = mouseX;
      this.sy = mouseY;
      noStroke();
      fill(255, 0, 0, a);
      size = 10;
    } else {
      stroke(r, g, b, a);
      noFill();
      size = 2;
      }      
    rect(this.sx, this.sy, size, size);    
  }
}
  
  
  void update() {
    this.sx += vx;
    this.sy += vy;
    if ((this.sx > width) || (this.sx < 0)) {
      vx = -vx;
    } else {
    if ((this.sy > 344) || (this.sy < 0)) {
      vy = -vy;
    }
    } 
  } // close void update()
  
} // close class Particle