added demo

demo/CirclePacking.pde

@@ -0,0 +1,104 @@
+float CORRECTION = 0.05, SPRING = 0.01;
+
+float angleSum(Vertex v)
+{
+  float res = 0;
+  ArrayList<Vertex> adjacent = v.degree();
+  float x = v.weight;
+  for(int i = 1; i < adjacent.size()+1; i++)
+  {
+    Vertex v1 = adjacent.get(i-1);
+    Vertex v2 = adjacent.get(i%adjacent.size());
+//    if(!v1.internal)  v1 = tri.imaginary;
+//    if(!v2.internal)  v2 = tri.imaginary;
+    float y = v1.weight;
+    float z = v2.weight;
+    res += Math.acos(((x+y)*(x+y) + (x+z)*(x+z) - (y+z)*(y+z))/(2*(x+y)*(x+z)));
+  }
+  return res;
+}
+
+void placeVertex(Vertex targ, float theta,  Vertex ref)
+{
+  targ.x = (ref.weight + targ.weight)*cos(theta) + ref.x;
+  targ.y = (ref.weight + targ.weight)*sin(theta) + ref.y;
+  targ.placed = true;
+}
+
+//thurston algorithm
+void computePacking(Triangulation t)
+{
+  for(Vertex v : t.outerVerts)
+    v.placed = false;
+  for(int i = 0; i < t.verticies.size(); i++)
+  {
+    if(t.verticies.get(i).h==null)
+    {
+      t.verticies.remove( t.verticies.get(i));
+      i--;
+      continue;
+    }
+    t.verticies.get(i).placed = false;
+    t.verticies.get(i).processed = false;
+  }
+  //compute radii to some threshhold
+  for(int i= 0; i < 100; i++)
+  {
+    for(int j = 0; j <  t.verticies.size(); j++)
+    {
+      float csum = angleSum( t.verticies.get(j));
+      if(csum < 2*PI)
+         t.verticies.get(j).weight -= 0.01;
+      else if(csum > 2*PI)
+         t.verticies.get(j).weight += 0.01;  
+    }
+  }
+  //fix an arbitrary internal vertex
+  t.verticies.get(0).placed = true;
+
+  JQueue<Vertex> q = new JQueue<Vertex>();
+
+  q.add(t.verticies.get(0));
+  int cnt = 0;
+  while(!q.isEmpty())
+  {
+    cnt++;
+    Vertex iv = q.remove();
+
+    ArrayList<Vertex> adjacent = iv.degree();//ordered neighbors
+    int i,j;
+    for(i = 0; i < adjacent.size() && !adjacent.get(i).placed; i++);
+    //find a placed petal, if there is one
+    float lastAngle = 0;
+
+    if(i==adjacent.size() && !adjacent.get(i-1).placed)  
+    {//initialization
+      i--; 
+      lastAngle = atan2(adjacent.get(i).y-iv.y,adjacent.get(i).x-iv.x);
+      placeVertex(adjacent.get(i), lastAngle, iv);
+      if(adjacent.get(i).internal)  
+        q.add(adjacent.get(i));
+    }
+
+    j = i;
+    while(++j % adjacent.size() != i)
+    {
+      Vertex v = adjacent.get(j % adjacent.size());
+      if(!v.placed)
+      {
+        Vertex lastKnown = adjacent.get((j-1)%adjacent.size());
+        lastAngle = atan2(lastKnown.y-iv.y,lastKnown.x-iv.x);
+
+        float x = iv.weight;
+        float y = lastKnown.weight;
+        float z = v.weight;
+        float theta = (float)Math.acos(((x+y)*(x+y) + (x+z)*(x+z) - (y+z)*(y+z))/(2*(x+y)*(x+z)));
+        placeVertex(v, lastAngle-theta, iv);
+      }
+      if(!v.processed && v.internal)
+        q.add(v);
+    }
+    iv.processed = true;
+  }
+}
+