import processing.opengl.*;

MyImage[] images;

void setup()
{
 size(640, 480, OPENGL);       //size of window and render mode
 images = new MyImage[10];
 images[0] = new MyImage(5,8,60,40,30,"0.gif");
 images[1] = new MyImage(9,2,60,40,30,"1.gif");
 images[2] = new MyImage(2,6,60,40,30,"2.gif");
 images[3] = new MyImage(4,3,60,40,30,"3.gif");
 images[4] = new MyImage(6,9,60,40,30,"4.gif");
 images[5] = new MyImage(7,4,60,40,30,"5.gif");
 images[6] = new MyImage(5,6,60,40,30,"6.gif");
 images[7] = new MyImage(8,7,60,40,30,"7.gif");
 images[8] = new MyImage(3,1,60,40,30,"8.gif");
 images[9] = new MyImage(1,5,60,40,30,"9.gif");
}

void draw()
{
 background(33);
 frameRate(15);
 update();
 display();
}

void update(){
 for(int i = 0; i < images.length; i++){
   images[i].update();
 }
}

void display(){
 noStroke();
 for(int i = 0; i < images.length; i++){
   images[i].drawTail();
 }
 for(int i = 0; i < images.length; i++){
   images[i].drawImg();
 }
}

class MyImage{
 int[][] pos;
 int dx;
 int dy;
 int w;
 int h;
 int l;
 PImage img;

 MyImage(int dx, int dy, int w, int h, int l, String imgName){
   this.dx = dx;
   this.dy = dy;
   this.w = w;
   this.h = h;
   this.l = l-1;
   pos = new int[this.l+1][2];
   img = loadImage(imgName);
 }

 void update(){
   checkBounds();
   shiftPos();
   addPos();
 }

 void drawTail(){
   for(int i = 0; i < l; i++){
     fill(255,255*i/l);
     rect(pos[i][0],pos[i][1],w*i/l,h*i/l);
   }
 }
 
 void drawImg(){
   image(img,pos[l][0],pos[l][1]);
 }
 
 private void checkBounds(){
   if(pos[l][0] < 0 || pos[l][0] > width-w)
   dx*=-1;
   if(pos[l][1] < 0 || pos[l][1] >     height-h)
   dy*=-1;
 }

 private void shiftPos(){
   for(int i = 1; i < l+1; i++){
     pos[i-1][0] = pos[i][0];
     pos[i-1][1] = pos[i][1];
   }
 }

 private void addPos(){
   pos[l][0] = pos[l-1][0]+dx;
   pos[l][1] = pos[l-1][1]+dy;
 }
}