incremental

main/HalfEdge.pde

@@ -23,6 +23,24 @@ public class HalfEdge {
     vertex = v1;
     twin.setOrigin(v2);
 
+
+    HalfEdge[] try1 = v1.getEdgesToUpdate(v2);
+    if (try1 == null) {
+       twin.setnext(this);
+       previous = twin;
+    } else {
+       twin.setnext(try1[1]);
+       previous = try1[0];
+    }
+
+    HalfEdge[] try2 = v2.getEdgesToUpdate(v1);
+    if (try2 == null) {
+       twin.setprevious(this);
+       next = twin;
+    } else {
+       twin.setprevious(try2[0]);
+       next = try2[1];
+    }
     // Set Nexts
 
     // Set Prevs

main/Vertex.pde

@@ -39,18 +39,34 @@ public class Vertex {
     ArrayList<HalfEdge> leaving = getAllLeavingEdges();
     HalfEdge[] prevNext = new HalfEdge[2];
     if (leaving.size() == 1) {
-      prevNext[0] = leaving.get(0);
-      prevNext[1] = prevNext[0].gettwin();
+      prevNext[1] = leaving.get(0);
+      prevNext[0] = prevNext[0].gettwin();
       return prevNext;
     }
-
-
-
-
+    Vertex v1 = this;
+    Vertex v4 = v;
+    Vertex v2;
+    Vertex v3;
+    int[] temp = new int[leaving.size()];
     for (int i = 0; i < leaving.size(); i++) {
-
+       temp[i] = 0; 
     }
-
+    for (int i = 0; i < leaving.size(); i++) {
+      v2 = leaving.get(i).getOrigin();
+      v3 = leaving.get((i+1)%leaving.size()).getOrigin(); 
+      if (is2closerCCWof4(v1, v2, v3, v4)) {
+        temp[i]++;
+      } else {
+        temp[(i+1)%leaving.size()]++;
+      }
+    }
+    for (int i = 0; i < leaving.size(); i++) {
+      if (temp[i] == 0) { 
+        prevNext[1] = leaving.get(i);
+        prevNext[0] = prevNext[1].getprevious();
+      } 
+    }
+    return prevNext;
   }
 
   private float[] safeSlope(float dy, float dx) {