i've seen this collision tecniques in actionscript3:

http://www.mikechambers.com/blog/2009/06/24/using-bitmapdata-hittest-for-collision-detection/

the key function is BitmapData.hitTest and i want to implement it in processing.. i've looked for some image subtraction in processing but without result and my implementation (nested for loop in x,y with PGraphics.get) is really too slow and my processing.org ide contue to crash..

some advice?

EDIT: i found the first error: i could check only perimeter not the whole rect!

EDIT 2: the right code, it works mayebe it could be more optimezed!

ps. this is my code:

2. 
   
3. int stage = 600;
4. int grow_limit = 50;
5. 
   
6. PGraphics buffer = createGraphics(stage, stage, P2D); //createImage(stage, stage, ALPHA);
7. 
   
8. ArrayList rects = new ArrayList();
9. 
   
10. color bg = color(55,30,115);
11. 
    
12. //------------------------------------------------------------------------------------- MAIN
13. //------------------------------------------------------------------------------------- MAIN
14. //------------------------------------------------------------------------------------- MAIN
15. 
    
16. void setup() {
17. 
    
18.   //size(*2stage, stage);
19.   size(stage, stage);
20.   background(bg);
21.   smooth();
22. 
    
23.   buffer.beginDraw();
24.   buffer.background(0);
25.   buffer.endDraw();
26. 
    
27.   addRect();addRect();addRect();addRect();addRect();addRect();addRect();
28. }
29. 
    
30. 
    
31. void draw() {
32.   
33.   Rectangle r;
34. 
    
35.   //println("rests: "+rects.size());
36. 
    
37.   for (int i=0; i<rects.size(); i++) {
38.     r = (Rectangle) rects.get(i);
39.     boolean dead = r.grow();
40.     if (dead) {
41.       rects.remove(i);
42.       addRect();
43.     }
44.   }
45.   //image(buffer, stage, 0);
46. }
47. 
    
48. void addRect() {
49.   int x = (int)random(stage);
50.   int y = (int)random(stage);
51.   addRect(x, y);
52. }
53. void addRect(int x, int y) {
54.   //println("addRect "+rects.size());
55.   rects.add(new Rectangle(x, y));
56. }
57. 
    
58. boolean hittest(Rectangle r) {
59.   /** Return True if there is no collision. False otherways. **/
60. 
    
61.   //println("hittest");
62. 
    
63.   if (r.x+r.w > stage) return false;
64.   if (r.y+r.h > stage) return false;
65. 
    
66.   // check only the perimeter!!
67.   int i=0, j=0;
68.   j = r.y;
69. 
    
70.   int flag = 0;
71. 
    
72.   j = r.y -1;
73.   for (i=r.x; i<(r.x+r.w); i++) flag += checkPixel(i, j);
74. 
    
75.   j = r.y+r.h +1;
76.   for (i=r.x; i<(r.x+r.w); i++) flag += checkPixel(i, j);
77. 
    
78.   i = r.x -1;
79.   for (j=r.y; j<(r.y+r.h); j++) flag += checkPixel(i, j);
80. 
    
81.   i = r.x+r.w +1;
82.   for (j=r.y; j<(r.y+r.h); j++) flag += checkPixel(i, j);
83. 
    
84.   return flag==0;
85. }
86. 
    
87. int checkPixel(int i, int j) {
88.   color black = color(0);
89.   if ( buffer.get(i, j) == black) return 0;
90.   else return 1;
91. }
92. 
    
93. //------------------------------------------------------------------------------------- RECTANGLE
94. //------------------------------------------------------------------------------------- RECTANGLE
95. //------------------------------------------------------------------------------------- RECTANGLE
96. 
    
97. class Rectangle {
98.   
99.   int x, y, w, h;
100.   boolean dead = false;
101.   
102.   float rotation = random(TWO_PI);
103.   float delta = random(3,6);
104.   
105.   public Rectangle(int x, int y) {
106.     println("Rectangle > .");
107.     this.x = x;
108.     this.y = y;
109.     this.w = this.h = 2;
110.   }
111. 
     
112.   boolean grow() {
113.     this.h+=1;
114.     this.w+=1;
115. 
     
116.     if ( hittest(this) ) {
117. 
     
118.       if (h>grow_limit || w>grow_limit) dead = true;
119. 
     
120.       this.draw();
121.       buffer.beginDraw();
122.       buffer.noStroke();
123.       buffer.fill(100);
124.       buffer.rect(x, y, w, h);
125.       buffer.endDraw();
126.     } 
127.     else dead = true;
128.     
129.     return dead;
130.   }
131.   
132.   void draw() {
133.     
134.     fill(bla);
135.     stroke(blabla);
136.     rect(x, y, w, h);
137.   }
138. }

PS: ANY ADVICE OR ANY KIND OF CONSIDERATIONS ON THE CODE AND HOW TO DEBUG IT IS REALLY APPRECIATED