I'm trying to move two images between two textures, the problem is that the framerate is dropping to around 10 when doing this, and I eventually will need to move more than one image, so I'm guessing i'm doing something wrong here. :-)

Here's my snip of code so far:

2. import processing.opengl.*;
3. 
   
4. PImage a;
5. PImage b;
6. void setup(){
7.   size(800, 800, OPENGL);
8.   noStroke();
9.   a = loadImage("tex1.png");
10.   b = loadImage("tex2.png");
11. }
12. 
    
13. void draw(){
14.   background(0);
15. 
    
16.   updateTextures(a, b, 1);
17. 
    
18.   beginShape();
19.   texture(a);
20.   vertex(40, 80, 0, 0);
21.   vertex(320, 20, b.width, 0);
22.   vertex(380, 360, b.width, b.height);
23.   vertex(80, 380, 0, b.height);
24.   endShape();
25. 
    
26.   beginShape();
27.   texture(b);
28.   vertex(40, 430, 0, 0);
29.   vertex(350, 420, b.width, 0);
30.   vertex(330, 760, b.width, b.height);
31.   vertex(50, 780, 0, b.height);
32.   endShape();
33. 
    
34. }
35. 
    
36. void updateTextures(PImage img1, PImage img2, int speed){
37.   img1.loadPixels();
38.   img2.loadPixels(); 
39. 
    
40.   for(int i = 0; i < (img1.width * img1.height) - img1.width; i++) {
41.     img1.pixels[i] = img1.pixels[i + img1.width];
42.     if(i < img1.width){
43.       img1.pixels[((img1.width * img1.height) - img1.width) + i] = img2.pixels[i];
44.     }
45.     img2.pixels[i] = img2.pixels[i + img2.width];
46.   } 
47. 
    
48.   img1.updatePixels();
49.   img2.updatePixels();
50. }
    

     

    Any help would be very much appreciated!
51. 
    
52. Thanks!