diff --git a/drawing/Button.pde b/drawing/Button.pde
new file mode 100644
index 0000000..0d4acdf
--- /dev/null
+++ b/drawing/Button.pde
@@ -0,0 +1,37 @@
+class Button extends Gui_element{
+  ButtonEvent e;
+  int x,y,w,h;
+  color button_color;
+  boolean disable=false;
+  String str;
+  Button(int _x, int _y, int _w, int _h, color _c, String _s, ButtonEvent _e){
+    x=_x;y=_y;w=_w;h=_h;button_color=_c;str=_s;e=_e;
+  }
+  void draw(){
+    if(disable){
+      fill(200);
+    }else if(mouse_over){
+      fill(255,0,0);
+    }else {
+      fill(button_color);
+    }
+    noStroke();
+    rect(x,y,w,h);
+    textSize(10);
+    fill(0, 0, 0);
+    textAlign(CENTER,CENTER);
+    text(str,x+w/2,y+h/2);
+  }
+  void mouseMoved(){
+    mouse_over=(mouseX>=x&&mouseX<=x+w&&mouseY>=y&&mouseY<=(y+h));
+    if(mouse_over)gui_current=this;
+  }
+  void mousePressed(){
+    if(e!=null&&!disable)
+      e.onclick();
+  }
+}
+interface ButtonEvent{
+  void onclick();
+}
+
diff --git a/drawing/Edge.pde b/drawing/Edge.pde
index 7aabc0e..61d8851 100644
--- a/drawing/Edge.pde
+++ b/drawing/Edge.pde
@@ -1,4 +1,4 @@
-class Edge {
+class Edge extends Gui_element{
   Vertex v1,v2;
   Edge(Vertex _v1, Vertex _v2){
     v1=_v1;v2=_v2;
diff --git a/drawing/Graph.pde b/drawing/Graph.pde
index 0193b37..cb8a441 100644
--- a/drawing/Graph.pde
+++ b/drawing/Graph.pde
@@ -10,6 +10,13 @@ class Graph{
     return true;
   }
   
+  boolean ValidGraph(){
+    int min=Integer.MAX_VALUE;
+    for(Vertex i:V){
+      if(i.E.size()<=min)min=i.E.size();
+    }
+    return min==3;
+  }
   boolean check3edges_per_vertex(Vertex v){ 
       if(v.E.size()<3) return true;
       if(v.E.size()>=3) return false; 
diff --git a/drawing/Gui_element.pde b/drawing/Gui_element.pde
new file mode 100644
index 0000000..484c0eb
--- /dev/null
+++ b/drawing/Gui_element.pde
@@ -0,0 +1,7 @@
+abstract class Gui_element{
+  boolean mouse_over=false;
+  void draw(){};
+  void mouseMoved(){};
+  void mousePressed(){};
+  void mouseDragged(){};
+}
diff --git a/drawing/Vertex.pde b/drawing/Vertex.pde
index 6be53a8..c9b290c 100644
--- a/drawing/Vertex.pde
+++ b/drawing/Vertex.pde
@@ -1,29 +1,20 @@
-class Vertex{
+class Vertex extends Gui_element{
   int x,y;
-  boolean mouseover=false;
   ArrayList<Edge> E=new ArrayList();
   Vertex(int _x,int _y){
     x=_x;y=_y;
   }
-  Vertex(int _x,int _y,boolean _mo){
-    x=_x;y=_y;mouseover=_mo;
-    if(_mo)vertex_under_mouse=this;
-  }
   void draw(){
     noStroke();
-    if(mouseover){
+    if(mouse_over){
       fill(0,255,0);
     }else{
       fill(255,0,0);
     }
     ellipse(x,y,Vertex_Rad*2,Vertex_Rad*2);
   }
-  void checkmouseover(){
-    if(sqrt((mouseX-x)*(mouseX-x)+(mouseY-y)*(mouseY-y))<=Vertex_Rad*2){
-      mouseover=true;
-      vertex_under_mouse=this;
-    }else{
-      mouseover=false;
-    }
+  void mouseMoved(){
+    mouse_over=(sqrt((mouseX-x)*(mouseX-x)+(mouseY-y)*(mouseY-y))<=Vertex_Rad*2);
+    if(mouse_over)gui_current=this;
   }
 }
diff --git a/drawing/drawing.pde b/drawing/drawing.pde
index 1336647..b82b80a 100644
--- a/drawing/drawing.pde
+++ b/drawing/drawing.pde
@@ -1,144 +1,191 @@
+import papaya.*;
+
 
 final int DRAW_NORMAL=1;
 final int DRAW_DRAG=2;
+final int DRAW_ANIMATION=3;
 final int Vertex_Rad=8;
-// define parameters for rectangular button
-  int rectX1=500, rectY1=500;
-  int rectX2=500, rectY2=550;
-  int rectwidth=80;
-  int rectheight=40;
-  color rectColor;
-  color rectHighlight;
-  boolean rectover=false;
-  
+ArrayList<Gui_element> gui=new ArrayList();
+Gui_element gui_current=null;
 Vertex drag_start;
-Vertex vertex_under_mouse;
+Graph G=new Graph();
+Button draw_button=new Button(500, 450, 80, 40, color(150), "Tutte Draw", new TutteDrawEvent());
+float[][] orig,targ;
+int animation_start_time=0;
+final int animation_duration=1000;
 void setup() {
   size(600, 600);
   background(255);
-  rectColor=(150);
-  rectHighlight=color(255,0,0);
-  rectX1=500;
-  rectY1=500;
-  noStroke();
+  draw_button.disable=true;
+  gui.add(draw_button);
+  gui.add(new Button(500, 500, 80, 40, color(150), "Initial Graph", new InitialGraphEvent()));
+  gui.add(new Button(500, 550, 80, 40, color(150), "Reset", new ResetEvent()));
 }
-Graph G=new Graph();
 int draw_state=DRAW_NORMAL;
 
 void draw() {
   background(255);
-  //Draw everything else
-  //Draw Vertices
-  for(Vertex i:G.V){
-    i.draw();
+  if(draw_state==DRAW_ANIMATION){
+    if(millis()-animation_start_time>animation_duration){
+      for(int i=0;i<G.V.size();++i){
+        G.V.get(i).x=(int)targ[i][0];
+        G.V.get(i).y=(int)targ[i][1];
+      }
+      draw_state=DRAW_NORMAL;
+    }else{
+      for(int i=0;i<G.V.size();++i){
+        G.V.get(i).x=(int)((targ[i][0]-orig[i][0])*(millis()-animation_start_time)/animation_duration+orig[i][0]);
+        G.V.get(i).y=(int)((targ[i][1]-orig[i][1])*(millis()-animation_start_time)/animation_duration+orig[i][1]);
+      }
+    }
   }
-  
-  mouse_over_BUTTON();
-  
-  //Draw Edges
-  strokeWeight(2);
-  for(Edge i:G.E){
+  for (Gui_element i : gui) {
     i.draw();
   }
-  if(draw_state==DRAW_DRAG){
+  if (draw_state==DRAW_DRAG) {
     strokeWeight(2);
-    stroke(0,0,255);
-    line(drag_start.x,drag_start.y,mouseX,mouseY);
+    stroke(0, 0, 255);
+    line(drag_start.x, drag_start.y, mouseX, mouseY);
+
     //println("DRAW_DRAG:",drag_start.x,",",drag_start.y,",",mouseX,",",mouseY);
     //Draw the dragged line;
   }
 }
 
-boolean check_mouse_over_button(int x, int y,int _height,int _width){
-  if(mouseY>=y && (mouseY-y<_height) &&(mouseX-x<_width)&& mouseX>=x)
-      rectover=true;
-  else rectover=false;
-   
-  return rectover;
-
-}
-void mouseMoved(){
-  vertex_under_mouse=null;
-  for(Vertex i:G.V){
-    i.checkmouseover();
+void mouseMoved() {
+  gui_current=null;
+  for (Gui_element i : gui) {
+    i.mouseMoved();
   }
 }
-void mouseDragged(){
+void mouseDragged() {
   mouseMoved();
-  if(draw_state!=DRAW_DRAG){//start dragging
-    drag_start=vertex_under_mouse;
-    draw_state=DRAW_DRAG;
+  if (draw_state!=DRAW_DRAG) {//start dragging
+    if (gui_current!=null&&gui_current instanceof Vertex) {
+      drag_start=(Vertex)gui_current;
+      draw_state=DRAW_DRAG;
+    }
   }
-  
 }
-void mousePressed(){
-  if(vertex_under_mouse==null && !check_mouse_over_button(rectX1,rectY1,rectheight,rectwidth) &&!check_mouse_over_button(rectX2,rectY2,rectheight,rectwidth)){
-    G.V.add(new Vertex(mouseX, mouseY,true));
+void mousePressed() {
+  if (gui_current==null) {
+    Vertex v=new Vertex(mouseX, mouseY);
+    G.V.add(v);
+    gui.add(v);
+    draw_button.disable=!G.ValidGraph();
+  } else {
+    gui_current.mousePressed();
   }
-
 }
 
-void mouseReleased(){
-  if(draw_state==DRAW_DRAG){
+void mouseReleased() {
+  if (draw_state==DRAW_DRAG) {
     draw_state=DRAW_NORMAL;
-    if(vertex_under_mouse!=null){
-      if(G.ValidNewEdge(drag_start,vertex_under_mouse)){
-        G.E.add(new Edge(drag_start,vertex_under_mouse));
+    if (gui_current!=null&&(gui_current instanceof Vertex)) {
+      if (G.ValidNewEdge(drag_start, (Vertex)gui_current)) {
+        Edge e=new Edge(drag_start, (Vertex)gui_current);
+        G.E.add(e);
+        gui.add(e);
+        draw_button.disable=!G.ValidGraph();
         println("Valid");
-      }else{
+      } else {
         println("Invalid");
       }
     }
   }
 }
 
-
-void mouse_over_BUTTON(){
-
-  if(check_mouse_over_button(rectX1,rectY1,rectheight,rectwidth)){
-    fill(255,0,0);
-  }else {
-  fill(rectColor);
+class InitialGraphEvent implements ButtonEvent {
+  void onclick() {
+    if (G.V.size()<=3) throw new RuntimeException("Requires at least 4 points"); 
+    for (int i=0; i<G.V.size (); i++) {
+      do {
+        stroke(0, 0, 255);
+        strokeWeight(2);
+        int l= int(random(G.V.size()));
+        println(l);
+        //add the drawn edge to the graph 
+        if (G.ValidNewEdge(G.V.get(i), G.V.get(l))) {   //have to check the whether the randomly selected vertex has three edges????
+          Edge e=new Edge(G.V.get(i), G.V.get(l));
+          G.E.add(e);
+          gui.add(e);
+        }
+      }while (G.check3edges_per_vertex (G.V.get (i)));
+      draw_button.disable=!G.ValidGraph();
+    }
+  }
+}
+class ResetEvent implements ButtonEvent {
+  void onclick() {
+    G.E.clear();
+    G.V.clear();
+    gui.clear();
+    setup();
   }
-   noStroke();
-   rect(rectX1,rectY1,rectwidth,rectheight);
-   textSize(10);
-   fill(0, 0, 0);
-   text("Initial Graph",rectX1+rectwidth/8,rectY1+rectheight/2);
-   
-  if(check_mouse_over_button(rectX2,rectY2,rectheight,rectwidth))
-    fill(255,0,0);
-  else 
-   fill(rectColor);
-   
-   rect(rectX2,rectY2,rectwidth,rectheight);
-   textSize(10);
-   fill(0, 0, 0);
-   text("Reset",rectX2+rectwidth/8,rectY2+rectheight/2);
 }
 
-void mouseClicked(){
- if(check_mouse_over_button(rectX1,rectY1,rectheight,rectwidth)){
-  //draw edges should be implemented by pressing button.
-    if (G.V.size()<=3) throw new RuntimeException("Requires at least 4 points"); 
-    for(int i=0;i<G.V.size();i++){
-     do{
-         stroke(0,0,255);
-         strokeWeight(2);
-         int l= int(random(G.V.size()));
-         println(l);
-        //add the drawn edge to the graph 
-         if(G.ValidNewEdge(G.V.get(i),G.V.get(l))){   //have to check the whether the randomly selected vertex has three edges????
-           G.E.add(new Edge(G.V.get(i),G.V.get(l)));     
-           line(G.V.get(i).x,G.V.get(i).y,G.V.get(l).x,G.V.get(l).y);
-         }
-        }while(G.check3edges_per_vertex(G.V.get(i)));
-      }
-     }
-       if(check_mouse_over_button(rectX2,rectY2,rectheight,rectwidth)){
-          G.E.clear();
-          G.V.clear();
+class TutteDrawEvent implements ButtonEvent {
+  void onclick() {
+    int l=G.V.size();
+    
+    //Matrix L
+    float[][] L=new float[l][l];
+    for(int i=0;i<l;++i){
+      for(int j=0;j<l;++j){//L[i][j]=...
+        if(i==j){
+          L[i][j]=G.V.get(i).E.size();
+        }else{
+          L[i][j]=0;
+          for(Edge k:G.V.get(i).E){
+            if(k.v1==G.V.get(j)||k.v2==G.V.get(j)){
+              L[i][j]=-1;break;
+            }
+          }
         }
+        //print(" ",L[i][j]);
+      }
+      //println();
+    }
+    
+    float[][] L1=new float[3][3];
+    float[][] L2=new float[l-3][l-3];
+    float[][] B=new float[l-3][3];
+    for(int i=0;i<3;++i){
+      for(int j=0;j<3;++j){
+        L1[i][j]=L[i][j];
+      }
+    }
+    for(int i=0;i<l-3;++i){
+      for(int j=0;j<l-3;++j){
+        L2[i][j]=L[i+3][j+3];
+      }
+    }
+    for(int i=0;i<l-3;++i){
+      for(int j=0;j<3;++j){
+        B[i][j]=L[i+3][j];
+      }
+    }
+    
+    float[][] P1=new float[][]{{10,10},{590,10},{300,590}};
+    float[][] invL2= Mat.inverse(L2);
+    float[][] nagP2=Mat.multiply(Mat.multiply(invL2,B),P1);
+    orig=new float[l][2];
+    targ=new float[l][2];
+    for(int i=0;i<3;++i){
+      orig[i][0]=G.V.get(i).x;
+      orig[i][1]=G.V.get(i).y;
+      targ[i][0]=(int)P1[i][0];
+      targ[i][1]=(int)P1[i][1];
+    }
+    for(int i=3;i<l;++i){
+      orig[i][0]=G.V.get(i).x;
+      orig[i][1]=G.V.get(i).y;
+      targ[i][0]=(int)-nagP2[i-3][0];
+      targ[i][1]=(int)-nagP2[i-3][1];
+    }
+    animation_start_time=millis();
+    draw_state=DRAW_ANIMATION;
+  }
 }