diff --git a/main/PointList.pde b/main/PointList.pde
index 3001f6f..c8e765f 100644
--- a/main/PointList.pde
+++ b/main/PointList.pde
@@ -51,6 +51,25 @@ public class PointList {
     return struct;
   }
   
+  public HalfEdge getHalfEdge(Point p, Point q) {
+    int num = points.size();
+    int id = -1;
+    for (int i = 0; i < num; i++) {
+      if (p.equals(points.get(i))) {
+        id = i;
+      }
+    }
+    HalfEdge first = p.getRef();
+    if (first == null) { return null; }
+    HalfEdge temp = first.gettwin().getnext();
+    while (temp != first) {
+      if (temp.gettwin().getOrigin().equals(q)) {
+        return temp; 
+      }
+    }
+    return null;
+  }
+  
   public boolean intersectsSomething(Point p, Point q) {
     ArrayList<HalfEdge> structures = getAllStructures();
     int num = structures.size();