// it falls!

class Flake {
  float x, y;
  float vx;
  int t;
  float depth;
  
  Flake(float xpos, float ypos, int type)
  {
    x = xpos;
    y = ypos;
    t = type;
    vx = 0;
    depth = random(5);
  }
}

class Snow {
  //PGraphics bg;
  PImage[] types;
  int w, h;
  Flake[] flakes;
  int newest;
  
  Snow(int wi, int hi)
  {
    w = wi;
    h = hi;
    types  = new PImage[2];
    types[0] = managedRequestImage("snow_1.gif");
    types[1] = managedRequestImage("snow_2.gif");
    //bg = createGraphics(w, h, P2D);
    flakes = new Flake[30];
    newest = 0;
  }
  
  void Draw(float xpos, float ypos, int s)
  {
    int rand = int(random(w*s));
    if (flakes[newest] == null)
    {
      if (rand % 50 == 0) {
        int type = 0;
        if (random(1) > .8)
          type = 1;
        flakes[newest] = new Flake(rand, 0, type);
        newest = (newest + 1) % flakes.length;
      }
    }
    
    //image(bg, xpos, ypos, bg.width*s, bg.height*s);
    
    for (int i = 0; i < flakes.length; i++)
    {
      rand = int(random(w));
      if (flakes[i] != null)
      {
        if (random(1) > .5)
        {
          flakes[i].y += rand % 2;
          flakes[i].vx += (rand % 3) - 1;
          if (flakes[i].vx > 5)
            flakes[i].vx = 5;
          if (flakes[i].vx < -5)
            flakes[i].vx = -5;
          flakes[i].x += flakes[i].vx * .2;
          if (flakes[i].x < 3*s)
            flakes[i].x = 3*s;
          if (flakes[i].x > (w-3)*s)
            flakes[i].x = (w-3)*s;
        }
        
        PImage type = types[flakes[i].t];
        image(type, xpos + flakes[i].x, ypos + flakes[i].y, type.width*s, type.height*s);
        
        if (flakes[i].y > (h - 10 + flakes[i].depth)*s)
        {
          //bg.beginDraw();
          //bg.image(type, flakes[i].x/s, flakes[i].y/s);
          //bg.endDraw();
          flakes[i] = null;
        }
      }
    }
  }
  
}