difficult...





you could have a list of branches and when you click, you add a branch.

But where?

Either at the last branch (which gives not a tree but a path) or at the nearest (which is not reliable).

You can select one branch to attach the new one to (that is my solution; select with cursor left and right - the selected is white)



Greetings, Chrisir    


[Edited: new version]

• use cursor left right to select
• and backspace to delete last one

1. // from http://processing.org/learning/topics/arraylistclass.html
2. //
3. ArrayList <Branch> branches;
4. int selectNumber=0;
5. // =====================================================================
6. void setup() {
7.   size(500, 500);
8.   // size(screen.width, screen.height); 
9.   smooth();
10.   noStroke();
11.   // Create an empty ArrayList
12.   branches = new ArrayList();
13.   // Start by adding one element
14.   int BranchWidth = 48;
15.   branches.add(new Branch(width/2, height,
16.   width/2+13, height-40,
17.   BranchWidth, color (random(0, 255), random(0, 255), random(0, 255))));
18. }
19. void draw() {
20.   // delete
21.   background(111);
22.   // With an array, we say branches.length, with an ArrayList, we say branches.size()
23.   // The length of an ArrayList is dynamic
24.   // Notice how we are looping through the ArrayList backwards
25.   for (int i = branches.size()-1; i >= 0; i--) {
26.     // get from ArrayList
27.     Branch Branch = branches.get(i);
28.     Branch.display(  i==selectNumber  );
29.   }
30. }
31. // =====================================================================
32. void mousePressed() {
33.   // A new Branch object is added to the ArrayList (by default to the end)
34.   //
35.   newBranch();
36. }
37. /*
38. void mouseDragged() {
39.  // A new Branch object is added to the ArrayList (by default to the end)
40.  //
41.  newBranch();
42.  }
43.  */
44. // =====================================================================
45. //
46. void keyPressed () {
47.   //
48.   if (key==CODED) {
49.     if (keyCode == LEFT) {
50.       selectNumber--;
51.       if (selectNumber<0) {
52.         selectNumber=0;
53.       }
54.     }
55.     if (keyCode == RIGHT) {
56.       selectNumber++;
57.       if (selectNumber>branches.size()) {
58.         selectNumber=branches.size();
59.       }
60.     }
61.   }
62.   else
63.   {
64.     if (key==BACKSPACE) {
65.       branches.remove(branches.size()-1);
66.     } // if
67.   } // else
68. } // func
69. //
70. void newBranch() {
71.   // A new Branch object is added to the ArrayList (by default to the end)
72.   //
73.   // different ways to determine parent branch: -------------------------
74.   // Branch Branch = branches.get( branches.size () -1 ); 
75.   // Branch Branch = getNearestBranch();   
76.   Branch Branch = getSelectedBranch();     
77.   branches.add(new Branch(
78.   Branch.x2, Branch.y2,
79.   mouseX, mouseY,
80.   mouseY*.1,
81.   color (random(0, 255), random(0, 255), random(0, 255))));
82. }
83. //
84. Branch getNearestBranch() {
85.   float smallestDist = 1000000;
86.   Branch buffer = null;
87.   for (int i = 0; i < branches.size(); i++) {
88.     // get from ArrayList
89.     Branch Branch = branches.get(i);
90.     if (dist(mouseX, mouseY, Branch.x2, Branch.y2) < smallestDist ) {
91.       smallestDist=dist(mouseX, mouseY, Branch.x2, Branch.y2);
92.       buffer = new Branch(2, 2, 2, 3, 2, 2);
93.       buffer= Branch;
94.     }
95.   }
96.   return buffer;
97. }
98. //
99. Branch getSelectedBranch() {
100.   float smallestDist = 1000000;
101.   Branch buffer = null;
102.   for (int i = 0; i < branches.size(); i++) {
103.     // get from ArrayList
104.     Branch Branch = branches.get(i);
105.     if (i==selectNumber) {
106.       buffer = new Branch(2, 2, 2, 3, 2, 2);
107.       buffer= Branch;
108.       return buffer;
109.     }
110.   }
111.   return null;
112. }
113. //
114. // =====================================================================
115. // Simple Branch class
116. class Branch {
117.   float x;
118.   float y;
119.   float x2;
120.   float y2;
121.   color myColor;
122.   //float speed;
123.   //float gravity;
124.   //float opacity;
125.   float w;
126.   //float life = 255;
127.   Branch(float tempX, float tempY,
128.   float tempX2, float tempY2,
129.   float tempW, color tempmyColor1) {
130.     x = tempX;
131.     y = tempY;
132.     x2 = tempX2;
133.     y2 = tempY2;   
134.     w = tempW;
135.     if (w<1) {
136.       w=1;
137.     }
138.     myColor=tempmyColor1;
139.   }
140.   //
141.   void display( boolean isSelected ) {
142.     // Display
143.     stroke(myColor);
144.     if (isSelected) {
145.       stroke(255);
146.     }
147.     strokeWeight(w);
148.     line(x, y, x2, y2);
149.   }
150.   //
151. } // class
152. // =====================================================================