1.   frame.setIconImage(g.image);

1. // M_4_1_01.pde
2. // Node.pde
3. //
4. // Generative Gestaltung, ISBN: 978-3-87439-759-9
5. // First Edition, Hermann Schmidt, Mainz, 2009
6. // Hartmut Bohnacker, Benedikt Gross, Julia Laub, Claudius Lazzeroni
7. // Copyright 2009 Hartmut Bohnacker, Benedikt Gross, Julia Laub, Claudius Lazzeroni
8. //
9. // http://www.generative-gestaltung.de
10. //
11. // Licensed under the Apache License, Version 2.0 (the "License");
12. // you may not use this file except in compliance with the License.
13. // You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
14. // Unless required by applicable law or agreed to in writing, software
15. // distributed under the License is distributed on an "AS IS" BASIS,
16. // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17. // See the License for the specific language governing permissions and
18. // limitations under the License.
19. /**
20.  * some moving nodes
21.  *
22.  * KEYS
23.  * r             : re-initialize velocity vectors of the nodes
24.  * s             : save png
25.  */
26. 
    
27. int nodeCount = 50;
28. 
    
29. // myNodes array
30. Node[] myNodes = new Node[nodeCount];
31. 
    
32. // image output
33. boolean saveOneFrame = false;
34. 
    
35. void setup() {
36.   size(600,600);
37.   frame.setResizable(true);
38.  
39.   // this Graphic object may change size as frame size changes
40.   g = createGraphics(600,600);
41.  
42.   g.colorMode(RGB, 255, 255, 255, 100);
43.   g.smooth();
44.   g.background(255);
45.   g.noStroke();
46.   g.fill(0);
47. 
    
48.   // setup myNodes
49.   for (int i = 0; i < nodeCount; i++) {
50.     myNodes[i] = new Node(random(width), random(height));
51.     myNodes[i].velocity.x = random(-3, 3);
52.     myNodes[i].velocity.y = random(-3, 3);
53.     myNodes[i].damping = 0.01;
54.     myNodes[i].c = color(random(255),random(255),random(255));
55.   }
56. }
57. 
    
58. void draw() { 
59.   // draw to PGraphics and retrieve frame image as icon
60.   g.beginDraw();
61.   // background(255); // no tail 
62.   g.fill(0, 5); // the smaller the alpha value, the longer the tail
63.   g.rect(0, 0, width, height);
64. 
    
65.   for (int i = 0; i < myNodes.length; i++) {
66.     myNodes[i].update();
67.     // draw node
68.     g.noStroke();
69.     g.fill(myNodes[i].c, 100);
70.     //g.fill(255, 100);
71.     g.ellipse(myNodes[i].x, myNodes[i].y, 10, 10);
72.   }
73.   g.endDraw();
74. 
    
75.   frame.setIconImage(g.image);
76.  
77.   // image output _______________________________________________________
78.   if(saveOneFrame == true) {
79.     saveFrame("_M_4_1_01_"+timestamp()+".png");
80.     saveOneFrame = false;
81.   }
82. }
83. 
    
84. void keyPressed(){
85.   if(key=='r' || key=='R') {
86.     for (int i = 0; i < nodeCount; i++) {
87.       myNodes[i].velocity.x = random(-5, 5);
88.       myNodes[i].velocity.y = random(-5, 5);
89.     }
90.   }
91.   if(key=='s' || key=='S') {
92.     saveOneFrame = true;
93.   }
94. }
95. 
    
96. String timestamp() {
97.   return String.format("%1$ty%1$tm%1$td_%1$tH%1$tM%1$tS", Calendar.getInstance());
98. }
99. 
    
100. class Node extends PVector {
101.   // velocity
102.   PVector velocity = new PVector();
103. 
     
104.   // minimum and maximum posiions
105.   float minX=5, minY=5, maxX=width-5, maxY=height-5;
106. 
     
107.   // damping of the velocity (0 = no damping, 1 = full damping)
108.   float damping = 0.1;
109. 
     
110.   // color
111.   color c;
112. 
     
113.   Node(float theX, float theY) {
114.     x = theX;
115.     y = theY;
116.   }
117. 
     
118.   // ------ calculate new position of the node ------
119.   void update() {
120.     maxX = width-5;  // update maxX using the width of the current window in case it is changed
121.     maxY = height-5; // update maxY using the height of the current window in case it is changed
122.    
123.     x += velocity.x;
124.     y += velocity.y;
125. 
     
126.     if (x < minX) {
127.       x = minX - (x - minX);
128.       velocity.x = -velocity.x;
129.     }
130. 
     
131.     if (x > maxX) {
132.       x = maxX - (x - maxX);
133.       velocity.x = -velocity.x;
134.     }
135. 
     
136.     if (y < minY) {
137.       y = minY - (y - minY);
138.       velocity.y = -velocity.y;
139.     }
140. 
     
141.     if (y > maxY) {
142.       y = maxY - (y - maxY);
143.       velocity.y = -velocity.y;
144.     }
145. 
     
146.     velocity.x *= (1-damping);
147.     velocity.y *= (1-damping);
148.   }
149. }

How can I find references on this type of default objects or variables in Processing?