I answered a similar question in the old forum: http://processing.org/discourse/yabb2/YaBB.pl?num=1236806404
No fades, sorry.

There are libraries like napplet and mother that allow for such a thing. However for simple sketches this is probably not necessary. The fading does add a level of complexity. Otherwise you could just use a simple switch. But since you want to display two sketches fading, you will need a different solution. I've created a code example using PGraphics because it allows you to fade between the offscreen renderings of different "sketches". You can add as many sketches as you want, check out the code for more explanation. You can loop through (aka fade between) sketches by pressing any key.

To automate transitions after a given time you can use frameCount or millis(). Search the forums for many examples. To create an image sequence you can use saveFrame, which you can then composite into a video using another program (for example Quicktime Pro or After Effects). You could also record to video directly. Search the forums, there are also many examples of this. Finally there are many examples that come with Processing covering a wide range of topics.

Code Example

1. int numSketches = 3; // we have three sketches: 0,1,2
2. float fadeSpeed = 0.01; // fading speed from one sketch to the next
3. PGraphics[] pgs = new PGraphics[numSketches];
4. int currentSketch;
5. boolean fading;
6. float fade, fc;
7.  
8. void setup() {
9.   size(600,600);
10.   // create offscreen graphics for all sketches
11.   for (int i=0; i<pgs.length; i++) {
12.     pgs[i] = createGraphics(width,height,JAVA2D);
13.   }
14. }
15.  
16. void draw() {
17.   fc = frameCount * 0.01;
18.  
19.   // run the current and, while fading, the next sketch
20.   for (int i=0; i<pgs.length; i++) {
21.     if (i == currentSketch % pgs.length) {
22.       sketches(i,pgs[i]);
23.     } else if (fading && i == (currentSketch + 1) % pgs.length) {
24.       sketches(i,pgs[i]);
25.     }
26.   }
27.  
28.   // fade from the current sketch to the next
29.   if (fading) {
30.     tint(255,(1-fade)*255);
31.     image(pgs[currentSketch % pgs.length],0,0);
32.     tint(255,fade*255);
33.     image(pgs[(currentSketch+1) % pgs.length],0,0);
34.     fade += fadeSpeed;
35.     // once the fading is complete...
36.     if (fade > 1) {
37.       fading = false;
38.       fade = 0;
39.       currentSketch++;
40.     }
41.   // if we are not fading, just display the current sketch
42.   } else {
43.     image(pgs[currentSketch % pgs.length],0,0);
44.   }
45. }
46.  
47. void keyPressed() {
48.   // start fading on a keyPress
49.   fading = true;
50. }
51.  
52. void sketches(int num, PGraphics pg) {
53.   if (num == 0) {
54.     // sketch ONE
55.     pg.beginDraw();
56.     pg.background(255);
57.     pg.smooth();
58.     pg.fill(0);
59.     pg.ellipse(noise(frameCount*0.01)*pg.width,noise(3+frameCount*0.005)*pg.height,100,100);
60.     pg.endDraw();
61.   } else if (num == 1) {
62.     // sketch TWO
63.     pg.beginDraw();
64.     pg.background(255,0,0);
65.     pg.noStroke();
66.     pg.rectMode(CENTER);
67.     pg.rect(pg.width/2,pg.height/2,noise(5+frameCount*0.01)*pg.width,noise(7+frameCount*0.01)*pg.height);
68.     pg.endDraw();
69.   } else if (num == 2) {
70.     // sketch THREE
71.     pg.beginDraw();
72.     pg.background(100,0,255);
73.     pg.smooth();
74.     pg.noStroke();
75.     pg.fill(255,0,0);
76.      pg.triangle(noise(4+fc)*pg.width,noise(6+fc)*pg.height,
77.      noise(5+fc)*pg.width,noise(7+fc)*pg.height,
78.      noise(9+fc)*pg.width,noise(1+fc)*pg.height);
79.     pg.endDraw();
80.   } else if (num == 3) {
81.     // sketch ETC.
82.     pg.beginDraw();
83.     // place your sketch between beginDraw and endDraw
84.     // put a pg in front of all relevant functions
85.     pg.endDraw();
86.   }
87. }

hello, thanks a lot, gonna study your code amnon.owed, looks nice
btw does napplet works on linux?

Thanks.