I'm not sure what you asking, but why not...

1. int nBlobs;
2. 
   
3. /* ... */
4. public void setup() {
5.    /* ... */
6.    nBlobs = 0; // or whatever initial value you have
7. }
8. public void draw() {
9.     int newBlobCount = some_way_of_determining_blob_count(); // whatever you have
10.     if (newBlobCount != nBlobs) {
11.          do_something_about_changed_blob_count();
12.          nBlobs = newBlobCount;
13.     }
14.     /* ...whatever else... */
15. }

?

kb, http://www.riftgame.com/

Hi Kevin,

Thanks for the reply. Sorry if my question was unclear. After researching more I think my answer lies in using an ArrayList. I need to read data regarding how many blobs are on the screen at a time. If the value changes then "do something". I think that I can create an ArrayList that records the number of blobs and cycle through it. Then I can compare two spots on the list to see if they are different and only "do something" if they are different. It is my understanding that you can cycle through an ArrayList by using remove. I'm a novice so this is taking a lot of time to figure out.

Anyway, maybe this makes more sense. If anyone has a better suggestion then please let me know.

The problem with your example is that it only compares to an initial value. I need the value to constantly update and to be compared to each subsequent value.

Thanks for the help. I appreciate it. : )

" It is my understanding that you can cycle through an ArrayList by using remove."
It depends on what you mean by "cycle". I first thought "iterate", but maybe you want to have a kind of circular list with fixed number of elements, hence the remove, removing at one end when you add to the other.
The various queue structures are also interesting.

To compare each value with the previous one, you can loop on the list. Using the modern notation, it can look like:

1. ArrayList<Blob> blobs;
2. 
   
3. // Init it somewhere
4. 
   
5. Blob prevBlob = null;
6. for (Blob blob : blobs)
7. {
8.   if (blob.equals(prevBlob))
9.   {
10.     // Do something
11.   }
12.   prevBlob = blob;
13. }

Thanks for your feedback philho and Kevin, I really appreciate it.

Kevin, yes you are right. I didn't look hard enough and I was trying to over-complicate things.Your solution is very simple and elegant and I'm sure it should work great if I can get my code to function properly. I think my code is just organized badly but I can't figure out why it won't run.

Here it is:

1. /*
2.  bounding boxes is a simple object tracking example.
3.  point the camera at some big bright objects and the boxes will follow.
4.  
5.  last tested to work in Processing 0090
6.  
7.  JTNIMOY
8.  
9. */
10. import JMyron.*;
11. Robot KeyBot; //Robot class for keypress
12. JMyron m;//a camera object
13. void setup(){
14.   size(320,240);
15.   m = new JMyron();//make a new instance of the object
16.   m.start(width,height);//start a capture at 320x240
17.   m.findGlobs(1);
18.   m.trackColor(0,0,0,200);//R, G, B, and range of similarity
19.   m.minDensity(1000); //minimum pixels in the glob required to result in a box
20.   println("Myron " + m.version());
21.   noFill();
22.   nBlobs = 0;
23.  
24.  
25.   
26.   try
27.   {
28.     KeyBot = new Robot();
29.   }
30.   catch (AWTException e)
31.   {
32.     println("Robot class not supported");
33.     exit();
34.   }
35.  
36. }
37. void draw(){
38.   m.update();//update the camera view
39.   drawCamera();//draw the camera to the screen
40.  
41.   int[][] b = m.globBoxes();//get list of bounding boxes
42.  
43.    //draw the boxes
44.   stroke(255,0,0);
45.   for(int i=0;i<b.length;i++){
46.     rect( b[i][0] , b[i][1] , b[i][2] , b[i][3] );
47.   }
48.  
49.   countTheBlobs();
50.    
51.   void drawCamera(){
52.   int[] img = m.image(); //get the normal image of the camera
53.   loadPixels();
54.   for(int i=0;i<width*height;i++){ //loop through all the pixels
55.     pixels[i] = img[i]; //draw each pixel to the screen
56.   }
57.   updatePixels();
58. }
59. void countTheBlobs() {
60.   int blobcount = b.length; //Number of blobs onscreen
61.   if (blobcount < 3){    //constrain values from 2 to 6
62.     blobcount = 2;
63.   }
64.   if (blobcount > 5){
65.     blobcount = 6;
66.   }
67.  
68.  if (blobcount != nBlob) {  //compares initial value to earlier value
69.    keyPressAction();        // if false, causes keypress
70.    nBlobs = blobcount;      // refreshes current value
71.  }
72. void mousePressed(){
73.   m.settings();//click the window to get the settings
74. }
75. public void stop(){
76.   m.stop();//stop the object
77.   super.stop();
78. }
79. void keyPressAction() {
80.   if (blobcount == 2) {
81.     KeyBot.keyPress(74);//press J key
82.     KeyBot.keyRelease(74);
83.     KeyBot.keyPress(74);//press J key
84.     KeyBot.keyRelease(74);
85.   }
86.   if (blobcount == 3) {
87.     KeyBot.keyPress(75);//press K key
88.     KeyBot.keyRelease(75);
89.     KeyBot.keyPress(75);//press K key
90.     KeyBot.keyRelease(75);
91.   }
92.   if (blobcount == 4) {
93.     KeyBot.keyPress(76);//press L key
94.     KeyBot.keyRelease(76);
95.     KeyBot.keyPress(76);//press L key
96.     KeyBot.keyRelease(76);
97.   }
98.   if (blobcount == 5) {
99.     KeyBot.keyPress(78);//press N key
100.     KeyBot.keyRelease(78);
101.     KeyBot.keyPress(78);//press N key
102.     KeyBot.keyRelease(78);
103.   }
104.   if (blobcount == 6) {
105.     KeyBot.keyPress(77);//press M key
106.     KeyBot.keyRelease(77);
107.     KeyBot.keyPress(77);//press M key
108.     KeyBot.keyRelease(77);
109.   }

I'm getting an unexpected token error (void) on the draw camera. The basic blob detection was working fine before and runs well for me. Sorry for my ignorance. I'm stuck right now. If anyone can see a problem or give me some organizational tips for my code I would be a happy camper.

Thanks again for all the help!
 

 I'm getting an unexpected token error (void) on the draw camera.

You need to keep better track of closing braces on methods: I count 3 missing braces in the code you posted...  on draw(), countTheBlobs() and keyPressAction().  It might be worth increasing the default tab depth in the IDE (IIRC you can do that in preferences.txt) as that might help you spot this type of problem more easily ;)

Ok. Thanks Kevin, philho, and blindfish for all of your help! I reorganized things and fixed some silly errors and it works really well. I'm not sure if the code is as optimized as it could be but it works great for me. Here is the finished code in case anyone ever needs it:

1. /*
2.  bounding boxes is a simple object tracking example.
3.  point the camera at some big bright objects and the boxes will follow.
4.  
5.  last tested to work in Processing 0090
6.  
7.  JTNIMOY
8.  
9. */
10. import JMyron.*;
11. Robot KeyBot; //Robot class for keypress
12. JMyron m;//a camera object
13. int nBlobs = 0; //initial value for comparison
14. void setup(){
15.   size(320,240);
16.   m = new JMyron();//make a new instance of the object
17.   m.start(width,height);//start a capture at 320x240
18.   m.findGlobs(1);
19.   m.trackColor(0,0,0,200);//R, G, B, and range of similarity
20.   m.minDensity(1000); //minimum pixels in the glob required to result in a box
21.   println("Myron " + m.version());
22.   noFill();
23.  
24.   try
25.   {
26.     KeyBot = new Robot();
27.   }
28.   catch (AWTException e)
29.   {
30.     println("Robot class not supported");
31.     exit();
32.   }
33.  
34. }
35. void draw(){
36.   m.update();//update the camera view
37.   drawCamera();//draw the camera to the screen
38.  
39.   int[][] b = m.globBoxes();//get list of bounding boxes
40.  
41.    //draw the boxes
42.   stroke(255,0,0);
43.   for(int i=0;i<b.length;i++){
44.   rect( b[i][0] , b[i][1] , b[i][2] , b[i][3] );
45.   }
46.  
47.   int blobcount = b.length; //Number of blobs onscreen
48.  
49.   if (blobcount < 3){    //constrain values returned from 2 to 6
50.     blobcount = 2;
51.   }
52.   if (blobcount > 5){
53.     blobcount = 6;
54.   }
55.  
56.   if (blobcount != nBlobs && blobcount == 2) {  //compares initial value to earlier value
57.     KeyBot.keyPress(74);//press J key
58.     KeyBot.keyRelease(74);
59.     KeyBot.keyPress(74);//press J key
60.     KeyBot.keyRelease(74);
61.   }
62.  
63.   else if (blobcount != nBlobs && blobcount == 3) {  //compares initial value to earlier value
64.     KeyBot.keyPress(75);//press K key
65.     KeyBot.keyRelease(75);
66.     KeyBot.keyPress(75);//press K key
67.     KeyBot.keyRelease(75);
68.   }
69.  
70.   else if (blobcount != nBlobs && blobcount == 4) {  //compares initial value to earlier value
71.     KeyBot.keyPress(76);//press L key
72.     KeyBot.keyRelease(76);
73.     KeyBot.keyPress(76);//press L key
74.     KeyBot.keyRelease(76);
75.   }
76.  
77.    else if (blobcount != nBlobs && blobcount == 5) {  //compares initial value to earlier value
78.     KeyBot.keyPress(78);//press N key
79.     KeyBot.keyRelease(78);
80.     KeyBot.keyPress(78);//press N key
81.     KeyBot.keyRelease(78);
82.   } 
83.    else if (blobcount != nBlobs && blobcount == 6) {  //compares initial value to earlier value
84.     KeyBot.keyPress(77);//press M key
85.     KeyBot.keyRelease(77);
86.     KeyBot.keyPress(77);//press M key
87.     KeyBot.keyRelease(77);
88.   }
89.  
90.    nBlobs = blobcount;      // refreshes current value
91.  }
92.    
93.   void drawCamera(){
94.   int[] img = m.image(); //get the normal image of the camera
95.   loadPixels();
96.   for(int i=0;i<width*height;i++){ //loop through all the pixels
97.     pixels[i] = img[i]; //draw each pixel to the screen
98.   }
99.   updatePixels();
100. }
101.  
102.  
103. void mousePressed(){
104.   m.settings();//click the window to get the settings
105. }
106. public void stop(){
107.   m.stop();//stop the object
108.   super.stop();
109. }
110.  
111.  
112.  
113.  

Thanks again!