From 7c0b972a953dc505fedea5b2d8e175148e94e392 Mon Sep 17 00:00:00 2001
From: Peng Xiao <peng.xiao@uconn.edu>
Date: Tue, 2 Dec 2014 21:57:18 -0500
Subject: [PATCH] Check if the graph the user draws is planar or not

---
 drawing/Graph.pde   | 4 +++-
 drawing/drawing.pde | 3 +++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drawing/Graph.pde b/drawing/Graph.pde
index cb8a441..322cb98 100644
--- a/drawing/Graph.pde
+++ b/drawing/Graph.pde
@@ -15,7 +15,9 @@ class Graph{
     for(Vertex i:V){
       if(i.E.size()<=min)min=i.E.size();
     }
-    return min==3;
+    boolean x= (min==3);
+    boolean y= E.size() <= (3*V.size() -6);
+    return x&&y;
   }
   boolean check3edges_per_vertex(Vertex v){ 
       if(v.E.size()<3) return true;
diff --git a/drawing/drawing.pde b/drawing/drawing.pde
index 6f862ef..acc1233 100644
--- a/drawing/drawing.pde
+++ b/drawing/drawing.pde
@@ -1,6 +1,7 @@
 import papaya.*;
 
 
+
 final int DRAW_NORMAL=1;
 final int DRAW_DRAG=2;
 final int DRAW_ANIMATION=3;
@@ -129,6 +130,8 @@ class ResetEvent implements ButtonEvent {
 
 class TutteDrawEvent implements ButtonEvent {
   void onclick() {
+    if (G.ValidGraph()==false)
+    throw new RuntimeException("Not a valid Graph!"); 
     int l=G.V.size();
     
     ArrayList<Vertex> face=FindFace();