diff --git a/build/dust3d.pro b/build/dust3d.pro
index 06f8a778..930d75a2 100644
--- a/build/dust3d.pro
+++ b/build/dust3d.pro
@@ -16,8 +16,8 @@ SOURCES += main.cpp \
   bmesh.c \
   matrix.c \
   convexhull.c \
-  tri2quad.c \
-  hashtable.c
+  hashtable.c \
+  osutil.cpp
 
 HEADERS += mainwindow.h \
 	render.h \
@@ -27,5 +27,6 @@ HEADERS += mainwindow.h \
   bmesh.h \
   matrix.h \
   convexhull.h \
-  tri2quad.h \
-  hashtable.h
\ No newline at end of file
+  hashtable.h \
+  3dstruct.h \
+  osutil.h
\ No newline at end of file
diff --git a/src/3dstruct.h b/src/3dstruct.h
new file mode 100644
index 00000000..1e0bcb79
--- /dev/null
+++ b/src/3dstruct.h
@@ -0,0 +1,21 @@
+#ifndef _3DSTRUCT_H
+#define _3DSTRUCT_H
+#include "vector3d.h"
+
+typedef struct {
+  vec3 pt[3];
+} triangle;
+
+typedef struct {
+  vec3 pt[4];
+} quad;
+
+typedef struct face3 {
+  int indices[3];
+} face3;
+
+typedef struct face4 {
+  int indices[4];
+} face4;
+
+#endif
diff --git a/src/bmesh.c b/src/bmesh.c
index fd3e2d8b..c07179ba 100644
--- a/src/bmesh.c
+++ b/src/bmesh.c
@@ -8,7 +8,6 @@
 #include "array.h"
 #include "matrix.h"
 #include "convexhull.h"
-#include "tri2quad.h"
 #include "draw.h"
 
 #define BMESH_STEP_DISTANCE 0.4
@@ -556,6 +555,10 @@ static void addBallToHull(convexHull *hull, bmeshBall *ballForConvexHull,
   }
 }
 
+#include "osutil.h"
+static int showFaceIndex = 0;
+static long long lastShowFaceIndexIncTime = 0;
+
 static int bmeshStichFrom(bmesh *bm, bmeshBall *parent, bmeshBall *ball) {
   int result = 0;
   bmeshBallIterator iterator;
@@ -566,7 +569,6 @@ static int bmeshStichFrom(bmesh *bm, bmeshBall *parent, bmeshBall *ball) {
   }
   ball->roundColor = bm->roundColor;
   if (BMESH_BALL_TYPE_ROOT == ball->type && 4 == ball->index) {
-    tri2QuadContext *t2q;
     convexHull *hull;
     bmeshBall *outmostBall = 0;
     int outmostBallFirstVertexIndex = 0;
@@ -575,12 +577,6 @@ static int bmeshStichFrom(bmesh *bm, bmeshBall *parent, bmeshBall *ball) {
       fprintf(stderr, "%s:convexHullCreate failed.\n", __FUNCTION__);
       return -1;
     }
-    t2q = tri2QuadContextCreate();
-    if (!t2q) {
-      fprintf(stderr, "%s:tri2QuadContextCreate failed.\n", __FUNCTION__);
-      convexHullDestroy(hull);
-      return -1;
-    }
     glColor3f(0.0, 0.0, 0.0);
     drawDebugPrintf("root <%f,%f,%f>", ball->position.x,
       ball->position.y, ball->position.z);
@@ -600,48 +596,54 @@ static int bmeshStichFrom(bmesh *bm, bmeshBall *parent, bmeshBall *ball) {
     }
     convexHullGenerate(hull);
     convexHullUnifyNormals(hull, &ball->position);
-    {
-      int triIndex;
-      for (triIndex = 0; triIndex < convexHullGetTriangleNum(hull);
-          ++triIndex) {
-        triangle *tri = (triangle *)convexHullGetTriangle(hull, triIndex);
-        tri2QuadAddTriangle(t2q, tri);
-      }
-    }
-    tri2QuadConvert(t2q);
-    
     glPushMatrix();
     
-    /*
+    if (lastShowFaceIndexIncTime + 300 < osGetMilliseconds()) {
+      if (showFaceIndex > convexHullGetFace3Num(hull)) {
+        showFaceIndex = 0;
+      } else {
+        showFaceIndex++;
+      }
+      lastShowFaceIndexIncTime = osGetMilliseconds();
+    }
+    
     glColor3f(1.0f, 1.0f, 1.0f);
     {
       int triIndex;
-      for (triIndex = 0; triIndex < convexHullGetTriangleNum(hull);
+      for (triIndex = 0; triIndex < convexHullGetFace3Num(hull);
           ++triIndex) {
-        triangle *tri = (triangle *)convexHullGetTriangle(hull, triIndex);
-        //if (triIndex > displayTriangleFaceIndex) {
-        //  continue;
-        //}
-        drawTriangle(tri);
+        triangle tri;
+        face3 *face = (face3 *)convexHullGetFace3(hull, triIndex);
+        tri.pt[0] = *convexHullGetVertex(hull, face->indices[0]);
+        tri.pt[1] = *convexHullGetVertex(hull, face->indices[1]);
+        tri.pt[2] = *convexHullGetVertex(hull, face->indices[2]);
+        if (triIndex > showFaceIndex) {
+          break;
+        }
+        drawTriangle(&tri);
       }
     }
     glColor3f(0.0f, 0.0f, 0.0f);
     {
       int triIndex;
       int j;
-      glColor3f(1.0f, 1.0f, 1.0f);
-      for (triIndex = 0; triIndex < convexHullGetTriangleNum(hull);
+      for (triIndex = 0; triIndex < convexHullGetFace3Num(hull);
           ++triIndex) {
-        triangle *tri = (triangle *)convexHullGetTriangle(hull, triIndex);
+        triangle tri;
+        face3 *face = (face3 *)convexHullGetFace3(hull, triIndex);
+        tri.pt[0] = *convexHullGetVertex(hull, face->indices[0]);
+        tri.pt[1] = *convexHullGetVertex(hull, face->indices[1]);
+        tri.pt[2] = *convexHullGetVertex(hull, face->indices[2]);
         glBegin(GL_LINE_STRIP);
         for (j = 0; j < 3; ++j) {
-          glVertex3f(tri->pt[j].x, tri->pt[j].y, tri->pt[j].z);
+          glVertex3f(tri.pt[j].x, tri.pt[j].y, tri.pt[j].z);
         }
-        glVertex3f(tri->pt[0].x, tri->pt[0].y, tri->pt[0].z);
+        glVertex3f(tri.pt[0].x, tri.pt[0].y, tri.pt[0].z);
         glEnd();
       }
     }
-    */
+  
+    /*
     glColor3f(1.0f, 1.0f, 1.0f);
     {
       int triIndex;
@@ -698,11 +700,10 @@ static int bmeshStichFrom(bmesh *bm, bmeshBall *parent, bmeshBall *ball) {
         glVertex3f(q->pt[0].x, q->pt[0].y, q->pt[0].z);
         glEnd();
       }
-    }
+    }*/
     
     glPopMatrix();
     convexHullDestroy(hull);
-    tri2QuadContextDestroy(t2q);
   }
   for (child = bmeshGetBallFirstChild(bm, ball, &iterator);
       child;
diff --git a/src/convexhull.c b/src/convexhull.c
index a0156143..27c0b276 100644
--- a/src/convexhull.c
+++ b/src/convexhull.c
@@ -4,7 +4,6 @@
 #include "convexhull.h"
 #include "array.h"
 #include "hashtable.h"
-#include "draw.h"
 
 //
 // Implement Gift wrapping method which describled in http://dccg.upc.edu/people/vera/wp-content/uploads/2014/11/GA2014-ConvexHulls3D-Roger-Hernando.pdf
@@ -18,19 +17,14 @@ typedef struct {
   int orderOnPlane;
 } converHullVertex;
 
-typedef struct face {
-  int indices[3];
-} face;
-
 struct convexHull {
   array *vertexArray;
   array *todoArray;
-  array *faceArray;
+  array *face3Array;
   int nextTodoIndex;
   unsigned int *openEdgeExistMap;
-  hashtable *faceHashtable;
-  face findFace;
-  triangle returnTriangle;
+  hashtable *face3Hashtable;
+  face3 findFace3;
 };
 
 typedef struct {
@@ -39,28 +33,33 @@ typedef struct {
   int thirdVertex;
 } todo;
 
-face *convexHullGetFaceByHashtableParam(convexHull *hull,
+static int cantorPair(int k1, int k2) {
+  return (k1 + k2) * (k1 + k2 + 1) / 2 + k2;
+}
+
+face3 *convexHullGetFaceByHashtableParam(convexHull *hull,
     const void *param) {
   int index = (char *)param - (char *)0;
   if (0 == index) {
-    return &hull->findFace;
+    return &hull->findFace3;
   }
-  return (face *)arrayGetItem(hull->faceArray, index - 1);
+  return (face3 *)arrayGetItem(hull->face3Array, index - 1);
 }
 
 static int faceHash(void *userData, const void *node) {
-  face *triIdx = convexHullGetFaceByHashtableParam(
+  face3 *triIdx = convexHullGetFaceByHashtableParam(
     (convexHull *)userData, node);
-  return triIdx->indices[0] * triIdx->indices[1] * triIdx->indices[2];
+  return cantorPair(cantorPair(triIdx->indices[0], triIdx->indices[1]),
+    triIdx->indices[2]);
 }
 
 static int faceCompare(void *userData, const void *node1,
     const void *node2) {
-  face *triIdx1 = convexHullGetFaceByHashtableParam(
+  face3 *triIdx1 = convexHullGetFaceByHashtableParam(
     (convexHull *)userData, node1);
-  face *triIdx2 = convexHullGetFaceByHashtableParam(
+  face3 *triIdx2 = convexHullGetFaceByHashtableParam(
     (convexHull *)userData, node2);
-  return memcmp(triIdx1, triIdx2, sizeof(face));
+  return memcmp(triIdx1, triIdx2, sizeof(face3));
 }
 
 convexHull *convexHullCreate(void) {
@@ -81,15 +80,15 @@ convexHull *convexHullCreate(void) {
     convexHullDestroy(hull);
     return 0;
   }
-  hull->faceArray = arrayCreate(sizeof(face));
-  if (!hull->faceArray) {
+  hull->face3Array = arrayCreate(sizeof(face3));
+  if (!hull->face3Array) {
     fprintf(stderr, "%s:arrayCreate failed.\n", __FUNCTION__);
     convexHullDestroy(hull);
     return 0;
   }
-  hull->faceHashtable = hashtableCreate(TRIANGLE_INDEX_HASHTABLE_SIZE,
+  hull->face3Hashtable = hashtableCreate(TRIANGLE_INDEX_HASHTABLE_SIZE,
     faceHash, faceCompare, hull);
-  if (!hull->faceHashtable) {
+  if (!hull->face3Hashtable) {
     fprintf(stderr, "%s:hashtableCreate failed.\n", __FUNCTION__);
     convexHullDestroy(hull);
     return 0;
@@ -163,9 +162,9 @@ static int sortface(const void *first, const void *second) {
   return *firstIndex - *secondIndex;
 }
 
-int convexHullAddFace(convexHull *hull, int firstVertex, int secondVertex,
+int convexHullAddFace3(convexHull *hull, int firstVertex, int secondVertex,
     int thirdVertex) {
-  face *tri;
+  face3 *tri;
   converHullVertex *vtx1;
   converHullVertex *vtx2;
   converHullVertex *vtx3;
@@ -191,21 +190,21 @@ int convexHullAddFace(convexHull *hull, int firstVertex, int secondVertex,
       return 0;
     }
   }
-  memset(&hull->findFace, 0, sizeof(hull->findFace));
-  hull->findFace.indices[0] = firstVertex;
-  hull->findFace.indices[1] = secondVertex;
-  hull->findFace.indices[2] = thirdVertex;
-  if (0 == hashtableGet(hull->faceHashtable, 0)) {
-    qsort(hull->findFace.indices, 3,
-      sizeof(hull->findFace.indices[0]), sortface);
-    newTri = arrayGetLength(hull->faceArray);
-    if (0 != arraySetLength(hull->faceArray, newTri + 1)) {
+  memset(&hull->findFace3, 0, sizeof(hull->findFace3));
+  hull->findFace3.indices[0] = firstVertex;
+  hull->findFace3.indices[1] = secondVertex;
+  hull->findFace3.indices[2] = thirdVertex;
+  qsort(hull->findFace3.indices, 3,
+    sizeof(hull->findFace3.indices[0]), sortface);
+  if (0 == hashtableGet(hull->face3Hashtable, 0)) {
+    newTri = arrayGetLength(hull->face3Array);
+    if (0 != arraySetLength(hull->face3Array, newTri + 1)) {
       fprintf(stderr, "%s:arraySetLength failed.\n", __FUNCTION__);
       return -1;
     }
-    tri = (face *)arrayGetItem(hull->faceArray, newTri);
-    *tri = hull->findFace;
-    if (0 != hashtableInsert(hull->faceHashtable,
+    tri = (face3 *)arrayGetItem(hull->face3Array, newTri);
+    *tri = hull->findFace3;
+    if (0 != hashtableInsert(hull->face3Hashtable,
         (char *)0 + newTri + 1)) {
       fprintf(stderr, "%s:hashtableInsert failed.\n", __FUNCTION__);
       return -1;
@@ -222,8 +221,8 @@ static void convexHullReleaseForGenerate(convexHull *hull) {
 void convexHullDestroy(convexHull *hull) {
   arrayDestroy(hull->vertexArray);
   arrayDestroy(hull->todoArray);
-  arrayDestroy(hull->faceArray);
-  hashtableDestroy(hull->faceHashtable);
+  arrayDestroy(hull->face3Array);
+  hashtableDestroy(hull->face3Hashtable);
   convexHullReleaseForGenerate(hull);
   free(hull);
 }
@@ -290,7 +289,8 @@ int convexHullGenerate(convexHull *hull) {
     todo *t = (todo *)arrayGetItem(hull->todoArray, hull->nextTodoIndex++);
     index1 = t->firstVertex;
     index2 = t->secondVertex;
-    if (convexHullEdgeExsits(hull, index1, index2)) {
+    if (convexHullEdgeExsits(hull, index1, index2) ||
+        convexHullEdgeExsits(hull, index2, index1)) {
       continue;
     }
     convexHullMarkEdgeAsExsits(hull, index1, index2);
@@ -298,8 +298,7 @@ int convexHullGenerate(convexHull *hull) {
     if (-1 == index3) {
       continue;
     }
-    convexHullAddFace(hull, index1, index2, index3);
-    convexHullAddTodo(hull, index1, index2, index3);
+    convexHullAddFace3(hull, index1, index2, index3);
     convexHullAddTodo(hull, index2, index3, index1);
     convexHullAddTodo(hull, index3, index1, index2);
   }
@@ -308,9 +307,9 @@ int convexHullGenerate(convexHull *hull) {
 
 int convexHullUnifyNormals(convexHull *hull, vec3 *origin) {
   int i;
-  for (i = 0; i < arrayGetLength(hull->faceArray); ++i) {
-    face *triIdx = (face *)arrayGetItem(
-      hull->faceArray, i);
+  for (i = 0; i < arrayGetLength(hull->face3Array); ++i) {
+    face3 *triIdx = (face3 *)arrayGetItem(
+      hull->face3Array, i);
     converHullVertex *p1 = (converHullVertex *)arrayGetItem(
       hull->vertexArray, triIdx->indices[0]);
     converHullVertex *p2 = (converHullVertex *)arrayGetItem(
@@ -330,19 +329,16 @@ int convexHullUnifyNormals(convexHull *hull, vec3 *origin) {
   return 0;
 }
 
-int convexHullGetTriangleNum(convexHull *hull) {
-  return arrayGetLength(hull->faceArray);
+face3 *convexHullGetFace3(convexHull *hull, int faceIndex) {
+  return (face3 *)arrayGetItem(hull->face3Array, faceIndex);
 }
 
-triangle *convexHullGetTriangle(convexHull *hull, int index) {
-  int i;
-  face *triIdx = (face *)arrayGetItem(
-    hull->faceArray, index);
-  memset(&hull->returnTriangle, 0, sizeof(hull->returnTriangle));
-  for (i = 0; i < 3; ++i) {
-    converHullVertex *vertex = (converHullVertex *)arrayGetItem(
-      hull->vertexArray, triIdx->indices[i]);
-    hull->returnTriangle.pt[i] = vertex->pt;
-  }
-  return &hull->returnTriangle;
+vec3 *convexHullGetVertex(convexHull *hull, int vertexIndex) {
+  converHullVertex *vertex = (converHullVertex *)arrayGetItem(
+    hull->vertexArray, vertexIndex);
+  return &vertex->pt;
+}
+
+int convexHullGetFace3Num(convexHull *hull) {
+  return arrayGetLength(hull->face3Array);
 }
diff --git a/src/convexhull.h b/src/convexhull.h
index 067d83dc..4d62e0c9 100644
--- a/src/convexhull.h
+++ b/src/convexhull.h
@@ -1,7 +1,6 @@
 #ifndef CONVEX_HULL_H
 #define CONVEX_HULL_H
-#include "vector3d.h"
-#include "draw.h"
+#include "3dstruct.h"
 
 typedef struct convexHull convexHull;
 convexHull *convexHullCreate(void);
@@ -10,8 +9,9 @@ int convexHullAddVertex(convexHull *hull, vec3 *vertex, int plane,
 void convexHullDestroy(convexHull *hull);
 int convexHullGenerate(convexHull *hull);
 int convexHullUnifyNormals(convexHull *hull, vec3 *origin);
-int convexHullGetTriangleNum(convexHull *hull);
-triangle *convexHullGetTriangle(convexHull *hull, int index);
+int convexHullGetFace3Num(convexHull *hull);
+face3 *convexHullGetFace3(convexHull *hull, int faceIndex);
+vec3 *convexHullGetVertex(convexHull *hull, int vertexIndex);
 int convexHullAddTodo(convexHull *hull, int vertex1, int vertex2, int vertex3);
 
 #endif
diff --git a/src/draw.h b/src/draw.h
index e623c439..450885fd 100644
--- a/src/draw.h
+++ b/src/draw.h
@@ -1,6 +1,6 @@
 #ifndef DRAW_SPHERE_H
 #define DRAW_SPHERE_H
-#include "vector3d.h"
+#include "3dstruct.h"
 #ifdef __APPLE__
 #include <OpenGL/glu.h>
 #else
@@ -11,19 +11,6 @@
 extern "C" {
 #endif
 
-typedef struct {
-  vec3 pt[3];
-} triangle;
-
-typedef struct {
-  vec3 pt[4];
-} quad;
-
-typedef struct {
-  int npoly;
-  triangle *poly;
-} object;
-
 int drawInit(void);
 int drawSphere(vec3 *origin, float radius, int slices, int stacks);
 void drawTriangle(triangle *poly);
diff --git a/src/osutil.cpp b/src/osutil.cpp
new file mode 100644
index 00000000..744200d4
--- /dev/null
+++ b/src/osutil.cpp
@@ -0,0 +1,6 @@
+#include "osutil.h"
+#include <QDateTime>
+
+long long osGetMilliseconds(void) {
+  return (long long)QDateTime::currentMSecsSinceEpoch();
+}
diff --git a/src/osutil.h b/src/osutil.h
new file mode 100644
index 00000000..5450cec9
--- /dev/null
+++ b/src/osutil.h
@@ -0,0 +1,14 @@
+#ifndef OS_UTIL_H
+#define OS_UTIL_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+long long osGetMilliseconds(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/src/tri2quad.c b/src/tri2quad.c
deleted file mode 100644
index e01c5bde..00000000
--- a/src/tri2quad.c
+++ /dev/null
@@ -1,324 +0,0 @@
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-#include <assert.h>
-#include "tri2quad.h"
-#include "vector3d.h"
-#include "array.h"
-#include "hashtable.h"
-
-#define EDGE_HASHTABLE_SIZE   100
-
-typedef struct edge {
-  vec3 p1;
-  vec3 p2;
-  int inputA;
-  int inputB;
-  int score;
-} edge;
-
-typedef struct inputTriangle {
-  triangle tri;
-  float area;
-  vec3 normal;
-  int merged;
-} inputTriangle;
-
-struct tri2QuadContext {
-  array *inputArray;
-  array *triangleArray;
-  array *quadArray;
-  array *edgeArray;
-  hashtable *edgeHashtable;
-  edge findEdge;
-};
-
-static edge *tri2QuadGetEdgeByHashtableParam(tri2QuadContext *ctx,
-    const void *param) {
-  int edgeIndex = (char *)param - (char *)0;
-  if (0 == edgeIndex) {
-    return &ctx->findEdge;
-  }
-  return (edge *)arrayGetItem(ctx->edgeArray, edgeIndex - 1);
-}
-
-static int edgeHash(void *userData, const void *node) {
-  edge *e = tri2QuadGetEdgeByHashtableParam((tri2QuadContext *)userData, node);
-  return (int)(e->p1.x + 1) * (e->p1.y + 1) * (e->p1.z + 1) *
-    (e->p2.x + 1) * (e->p2.y + 1) * (e->p2.z + 1);
-}
-
-static int edgeCompare(void *userData, const void *node1, const void *node2) {
-  const edge *e1 = (const edge *)tri2QuadGetEdgeByHashtableParam(
-    (tri2QuadContext *)userData, node1);
-  const edge *e2 = (const edge *)tri2QuadGetEdgeByHashtableParam(
-    (tri2QuadContext *)userData, node2);
-  if ((0 == memcmp(&e1->p1, &e2->p1, sizeof(e1->p1)) &&
-        0 == memcmp(&e1->p2, &e2->p2, sizeof(e1->p1))) ||
-      (0 == memcmp(&e1->p1, &e2->p2, sizeof(e1->p1)) &&
-        0 == memcmp(&e1->p2, &e2->p1, sizeof(e1->p1)))) {
-    return 0;
-  }
-  return -1;
-}
-
-tri2QuadContext *tri2QuadContextCreate(void) {
-  tri2QuadContext *ctx = (tri2QuadContext *)calloc(1, sizeof(tri2QuadContext));
-  if (!ctx) {
-    fprintf(stderr, "%s:Insufficient memory.", __FUNCTION__);
-    return 0;
-  }
-  ctx->inputArray = arrayCreate(sizeof(inputTriangle));
-  if (!ctx->inputArray) {
-    fprintf(stderr, "%s:arrayCreate failed.", __FUNCTION__);
-    tri2QuadContextDestroy(ctx);
-    return 0;
-  }
-  ctx->triangleArray = arrayCreate(sizeof(triangle));
-  if (!ctx->triangleArray) {
-    fprintf(stderr, "%s:arrayCreate failed.", __FUNCTION__);
-    tri2QuadContextDestroy(ctx);
-    return 0;
-  }
-  ctx->quadArray = arrayCreate(sizeof(quad));
-  if (!ctx->quadArray) {
-    fprintf(stderr, "%s:arrayCreate failed.", __FUNCTION__);
-    tri2QuadContextDestroy(ctx);
-    return 0;
-  }
-  ctx->edgeHashtable = hashtableCreate(EDGE_HASHTABLE_SIZE, edgeHash,
-    edgeCompare, ctx);
-  if (!ctx->edgeHashtable) {
-    fprintf(stderr, "%s:hashtableCreate failed.", __FUNCTION__);
-    tri2QuadContextDestroy(ctx);
-    return 0;
-  }
-  ctx->edgeArray = arrayCreate(sizeof(edge));
-  if (!ctx->edgeArray) {
-    fprintf(stderr, "%s:arrayCreate failed.", __FUNCTION__);
-    tri2QuadContextDestroy(ctx);
-    return 0;
-  }
-  return ctx;
-}
-
-int tri2QuadAddTriangle(tri2QuadContext *ctx, triangle *tri) {
-  int newInputIndex;
-  inputTriangle *newInput;
-  newInputIndex = arrayGetLength(ctx->inputArray);
-  if (0 != arraySetLength(ctx->inputArray, newInputIndex + 1)) {
-    fprintf(stderr, "%s:arraySetLength failed.", __FUNCTION__);
-    return -1;
-  }
-  newInput = (inputTriangle *)arrayGetItem(ctx->inputArray, newInputIndex);
-  newInput->merged = 0;
-  newInput->tri = *tri;
-  newInput->area = vec3TriangleArea(&tri->pt[0], &tri->pt[1], &tri->pt[2]);
-  vec3Normal(&tri->pt[0], &tri->pt[1], &tri->pt[2], &newInput->normal);
-  return newInputIndex;
-}
-
-static edge *tri2QuadFindEdge(tri2QuadContext *ctx,
-    vec3 *p1, vec3 *p2) {
-  int edgeIndex;
-  ctx->findEdge.p1 = *p1;
-  ctx->findEdge.p2 = *p2;
-  edgeIndex = (char *)hashtableGet(ctx->edgeHashtable, (char *)0) - (char *)0;
-  if (0 == edgeIndex) {
-    return 0;
-  }
-  return (edge *)arrayGetItem(ctx->edgeArray, edgeIndex - 1);
-}
-
-static int tri2QuadAddInitialEdge(tri2QuadContext *ctx,
-    vec3 *p1, vec3 *p2, int inputIndex) {
-  edge *existedEdge = tri2QuadFindEdge(ctx, p1, p2);
-  if (!existedEdge) {
-    edge *newEdge;
-    int newEdgeIndex = arrayGetLength(ctx->edgeArray);
-    if (0 != arraySetLength(ctx->edgeArray, newEdgeIndex + 1)) {
-      fprintf(stderr, "%s:arraySetLength failed(newEdgeIndex:%d).",
-        __FUNCTION__, newEdgeIndex);
-      return -1;
-    }
-    newEdge = (edge *)arrayGetItem(ctx->edgeArray, newEdgeIndex);
-    newEdge->p1 = *p1;
-    newEdge->p2 = *p2;
-    if (0 != hashtableInsert(ctx->edgeHashtable,
-        (char *)0 + newEdgeIndex + 1)) {
-      fprintf(stderr, "%s:hashtableInsert failed.", __FUNCTION__);
-      return -1;
-    }
-    newEdge->inputA = inputIndex;
-    newEdge->inputB = -1;
-    newEdge->score = 0;
-  } else {
-    existedEdge->inputB = inputIndex;
-  }
-  return 0;
-}
-
-static int tri2QuadAddOutputQuad(tri2QuadContext *ctx, vec3 *first,
-    vec3 *second, vec3 *third, vec3 *fourth) {
-  quad *q;
-  int newQuadIndex = arrayGetLength(ctx->quadArray);
-  if (0 != arraySetLength(ctx->quadArray, newQuadIndex + 1)) {
-    fprintf(stderr, "%s:arraySetLength failed(newQuadIndex:%d).", __FUNCTION__,
-      newQuadIndex);
-    return -1;
-  }
-  q = (quad *)arrayGetItem(ctx->quadArray, newQuadIndex);
-  memset(q, 0, sizeof(quad));
-  q->pt[0] = *first;
-  q->pt[1] = *second;
-  q->pt[2] = *third;
-  q->pt[3] = *fourth;
-  return newQuadIndex;
-}
-
-static int tri2QuadAddOutputTriangle(tri2QuadContext *ctx, vec3 *first,
-    vec3 *second, vec3 *third) {
-  triangle *tri;
-  int newTriangleIndex = arrayGetLength(ctx->triangleArray);
-  if (0 != arraySetLength(ctx->triangleArray, newTriangleIndex + 1)) {
-    fprintf(stderr, "%s:arraySetLength failed(newTriangleIndex:%d).",
-      __FUNCTION__, newTriangleIndex);
-    return -1;
-  }
-  tri = (triangle *)arrayGetItem(ctx->triangleArray, newTriangleIndex);
-  memset(tri, 0, sizeof(triangle));
-  tri->pt[0] = *first;
-  tri->pt[1] = *second;
-  tri->pt[2] = *third;
-  return newTriangleIndex;
-}
-
-static int tri2QuadAddOutputQuadByEdgeAndInput(tri2QuadContext *ctx, edge *e,
-    inputTriangle *input1, inputTriangle *input2) {
-  vec3 outputPt[4];
-  int i;
-  int nextSaveToIndex;
-  memset(outputPt, 0, sizeof(outputPt));
-  nextSaveToIndex = 0;
-  for (i = 0; i < 3; ++i) {
-    vec3 *pt = &input1->tri.pt[i];
-    if (0 == memcmp(&e->p1, pt, sizeof(e->p1))) {
-      outputPt[nextSaveToIndex] = *pt;
-      nextSaveToIndex += 2;
-    } else if (0 == memcmp(&e->p2, pt, sizeof(e->p2))) {
-      outputPt[nextSaveToIndex] = *pt;
-      nextSaveToIndex += 2;
-    } else {
-      outputPt[1] = *pt;
-    }
-  }
-  for (i = 0; i < 3; ++i) {
-    vec3 *pt = &input2->tri.pt[i];
-    if (0 != memcmp(&e->p1, pt, sizeof(e->p1)) &&
-        0 != memcmp(&e->p2, pt, sizeof(e->p2))) {
-      outputPt[3] = *pt;
-      break;
-    }
-  }
-  return tri2QuadAddOutputQuad(ctx, &outputPt[0], &outputPt[1],
-    &outputPt[2], &outputPt[3]);
-}
-
-static int sortEdgeByScoreDesc(const void *first, const void *second) {
-  const edge *e1 = (const edge *)first;
-  const edge *e2 = (const edge *)second;
-  return e2->score - e1->score;
-}
-
-int tri2QuadConvert(tri2QuadContext *ctx) {
-  int inputIndex;
-  int edgeIndex;
-  
-  for (inputIndex = 0; inputIndex < arrayGetLength(ctx->inputArray);
-      ++inputIndex) {
-    inputTriangle *inputItem = (inputTriangle *)arrayGetItem(ctx->inputArray,
-      inputIndex);
-    tri2QuadAddInitialEdge(ctx, &inputItem->tri.pt[0], &inputItem->tri.pt[1],
-      inputIndex);
-    tri2QuadAddInitialEdge(ctx, &inputItem->tri.pt[1], &inputItem->tri.pt[2],
-      inputIndex);
-    tri2QuadAddInitialEdge(ctx, &inputItem->tri.pt[2], &inputItem->tri.pt[0],
-      inputIndex);
-  }
-  for (edgeIndex = 0; edgeIndex < arrayGetLength(ctx->edgeArray); ++edgeIndex) {
-    edge *e = (edge *)arrayGetItem(ctx->edgeArray, edgeIndex);
-    inputTriangle *input1;
-    inputTriangle *input2;
-    if (-1 != e->inputA && -1 != e->inputB) {
-      input1 = (inputTriangle *)arrayGetItem(ctx->inputArray,
-        e->inputA);
-      input2 = (inputTriangle *)arrayGetItem(ctx->inputArray,
-        e->inputB);
-      e->score = (int)((input1->area + input2->area) *
-        vec3DotProduct(&input1->normal, &input2->normal) * 100);
-    }
-  }
-  qsort(arrayGetItem(ctx->edgeArray, 0), arrayGetLength(ctx->edgeArray),
-    sizeof(edge), sortEdgeByScoreDesc);
-  
-  //
-  // After qsort, the edge indices inside the hashtable are no longer right.
-  //
-  
-  hashtableDestroy(ctx->edgeHashtable);
-  ctx->edgeHashtable = 0;
-  
-  for (edgeIndex = 0; edgeIndex < arrayGetLength(ctx->edgeArray); ++edgeIndex) {
-    edge *e = (edge *)arrayGetItem(ctx->edgeArray, edgeIndex);
-    inputTriangle *input1;
-    inputTriangle *input2;
-    if (-1 != e->inputA && -1 != e->inputB) {
-      input1 = (inputTriangle *)arrayGetItem(ctx->inputArray,
-        e->inputA);
-      input2 = (inputTriangle *)arrayGetItem(ctx->inputArray,
-        e->inputB);
-      if (!input1->merged && !input2->merged) {
-        //input1->merged = 1;
-        //input2->merged = 1;
-        //tri2QuadAddOutputQuadByEdgeAndInput(ctx, e, input1, input2);
-      }
-    }
-  }
-  
-  for (inputIndex = 0; inputIndex < arrayGetLength(ctx->inputArray);
-      ++inputIndex) {
-    inputTriangle *inputItem = (inputTriangle *)arrayGetItem(ctx->inputArray,
-      inputIndex);
-    if (!inputItem->merged) {
-      tri2QuadAddOutputTriangle(ctx, &inputItem->tri.pt[0],
-        &inputItem->tri.pt[1], &inputItem->tri.pt[2]);
-    }
-  }
-  
-  return 0;
-}
-
-int tri2QuadGetTriangleNum(tri2QuadContext *ctx) {
-  return arrayGetLength(ctx->triangleArray);
-}
-
-triangle *tri2QuadGetTriangle(tri2QuadContext *ctx, int index) {
-  return (triangle *)arrayGetItem(ctx->triangleArray, index);
-}
-
-int tri2QuadGetQuadNum(tri2QuadContext *ctx) {
-  return arrayGetLength(ctx->quadArray);
-}
-
-quad *tri2QuadGetQuad(tri2QuadContext *ctx, int index) {
-  return (quad *)arrayGetItem(ctx->quadArray, index);
-}
-
-void tri2QuadContextDestroy(tri2QuadContext *ctx) {
-  arrayDestroy(ctx->inputArray);
-  arrayDestroy(ctx->triangleArray);
-  arrayDestroy(ctx->quadArray);
-  hashtableDestroy(ctx->edgeHashtable);
-  arrayDestroy(ctx->edgeArray);
-  free(ctx);
-}
diff --git a/src/tri2quad.h b/src/tri2quad.h
deleted file mode 100644
index f7053b9c..00000000
--- a/src/tri2quad.h
+++ /dev/null
@@ -1,17 +0,0 @@
-#ifndef TRI2QUAD_H
-#define TRI2QUAD_H
-#include "draw.h"
-
-typedef struct tri2QuadContext tri2QuadContext;
-
-tri2QuadContext *tri2QuadContextCreate(void);
-int tri2QuadAddTriangle(tri2QuadContext *ctx, triangle *tri);
-int tri2QuadConvert(tri2QuadContext *ctx);
-int tri2QuadGetTriangleNum(tri2QuadContext *ctx);
-triangle *tri2QuadGetTriangle(tri2QuadContext *ctx, int index);
-int tri2QuadGetQuadNum(tri2QuadContext *ctx);
-quad *tri2QuadGetQuad(tri2QuadContext *ctx, int index);
-void tri2QuadContextDestroy(tri2QuadContext *ctx);
-
-#endif
-