Add simple OpenGL viewer example.

5 files changed, 779 insertions, 0 deletions

diff --git a/examples/viewer/Makefile b/examples/viewer/Makefile
new file mode 100644
index 0000000..e5204fc
--- /dev/null
+++ b/examples/viewer/Makefile
@@ -0,0 +1,8 @@
+GLFW_INC=-I/usr/local/include 
+GLFW_LIBS=-L/usr/local/lib -lglfw3 -lglew
+GL_LIBS=-framework OpenGL
+
+CXX_FLAGS=-Wno-deprecated-declarations
+
+all:
+	g++ -fsanitize=address -O0 -g -o objviewer $(CXX_FLAGS) viewer.cc ../../tiny_obj_loader.cc trackball.cc $(GLFW_INC) $(GL_LIBS) $(GLFW_LIBS)
diff --git a/examples/viewer/README.md b/examples/viewer/README.md
new file mode 100644
index 0000000..4e0e087
--- /dev/null
+++ b/examples/viewer/README.md
@@ -0,0 +1 @@
+Simple .obj viewer with glew + glfw3 + OpenGL
diff --git a/examples/viewer/trackball.cc b/examples/viewer/trackball.cc
new file mode 100644
index 0000000..86ff3b3
--- /dev/null
+++ b/examples/viewer/trackball.cc
@@ -0,0 +1,292 @@
+/*
+ * (c) Copyright 1993, 1994, Silicon Graphics, Inc.
+ * ALL RIGHTS RESERVED
+ * Permission to use, copy, modify, and distribute this software for
+ * any purpose and without fee is hereby granted, provided that the above
+ * copyright notice appear in all copies and that both the copyright notice
+ * and this permission notice appear in supporting documentation, and that
+ * the name of Silicon Graphics, Inc. not be used in advertising
+ * or publicity pertaining to distribution of the software without specific,
+ * written prior permission.
+ *
+ * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
+ * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
+ * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
+ * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
+ * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
+ * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
+ * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
+ * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
+ * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
+ * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * US Government Users Restricted Rights
+ * Use, duplication, or disclosure by the Government is subject to
+ * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
+ * (c)(1)(ii) of the Rights in Technical Data and Computer Software
+ * clause at DFARS 252.227-7013 and/or in similar or successor
+ * clauses in the FAR or the DOD or NASA FAR Supplement.
+ * Unpublished-- rights reserved under the copyright laws of the
+ * United States.  Contractor/manufacturer is Silicon Graphics,
+ * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
+ *
+ * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
+ */
+/*
+ * Trackball code:
+ *
+ * Implementation of a virtual trackball.
+ * Implemented by Gavin Bell, lots of ideas from Thant Tessman and
+ *   the August '88 issue of Siggraph's "Computer Graphics," pp. 121-129.
+ *
+ * Vector manip code:
+ *
+ * Original code from:
+ * David M. Ciemiewicz, Mark Grossman, Henry Moreton, and Paul Haeberli
+ *
+ * Much mucking with by:
+ * Gavin Bell
+ */
+#include <math.h>
+#include "trackball.h"
+
+/*
+ * This size should really be based on the distance from the center of
+ * rotation to the point on the object underneath the mouse.  That
+ * point would then track the mouse as closely as possible.  This is a
+ * simple example, though, so that is left as an Exercise for the
+ * Programmer.
+ */
+#define TRACKBALLSIZE (0.8)
+
+/*
+ * Local function prototypes (not defined in trackball.h)
+ */
+static float tb_project_to_sphere(float, float, float);
+static void normalize_quat(float[4]);
+
+static void vzero(float *v) {
+  v[0] = 0.0;
+  v[1] = 0.0;
+  v[2] = 0.0;
+}
+
+static void vset(float *v, float x, float y, float z) {
+  v[0] = x;
+  v[1] = y;
+  v[2] = z;
+}
+
+static void vsub(const float *src1, const float *src2, float *dst) {
+  dst[0] = src1[0] - src2[0];
+  dst[1] = src1[1] - src2[1];
+  dst[2] = src1[2] - src2[2];
+}
+
+static void vcopy(const float *v1, float *v2) {
+  register int i;
+  for (i = 0; i < 3; i++)
+    v2[i] = v1[i];
+}
+
+static void vcross(const float *v1, const float *v2, float *cross) {
+  float temp[3];
+
+  temp[0] = (v1[1] * v2[2]) - (v1[2] * v2[1]);
+  temp[1] = (v1[2] * v2[0]) - (v1[0] * v2[2]);
+  temp[2] = (v1[0] * v2[1]) - (v1[1] * v2[0]);
+  vcopy(temp, cross);
+}
+
+static float vlength(const float *v) {
+  return sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
+}
+
+static void vscale(float *v, float div) {
+  v[0] *= div;
+  v[1] *= div;
+  v[2] *= div;
+}
+
+static void vnormal(float *v) { vscale(v, 1.0 / vlength(v)); }
+
+static float vdot(const float *v1, const float *v2) {
+  return v1[0] * v2[0] + v1[1] * v2[1] + v1[2] * v2[2];
+}
+
+static void vadd(const float *src1, const float *src2, float *dst) {
+  dst[0] = src1[0] + src2[0];
+  dst[1] = src1[1] + src2[1];
+  dst[2] = src1[2] + src2[2];
+}
+
+/*
+ * Ok, simulate a track-ball.  Project the points onto the virtual
+ * trackball, then figure out the axis of rotation, which is the cross
+ * product of P1 P2 and O P1 (O is the center of the ball, 0,0,0)
+ * Note:  This is a deformed trackball-- is a trackball in the center,
+ * but is deformed into a hyperbolic sheet of rotation away from the
+ * center.  This particular function was chosen after trying out
+ * several variations.
+ *
+ * It is assumed that the arguments to this routine are in the range
+ * (-1.0 ... 1.0)
+ */
+void trackball(float q[4], float p1x, float p1y, float p2x, float p2y) {
+  float a[3]; /* Axis of rotation */
+  float phi;  /* how much to rotate about axis */
+  float p1[3], p2[3], d[3];
+  float t;
+
+  if (p1x == p2x && p1y == p2y) {
+    /* Zero rotation */
+    vzero(q);
+    q[3] = 1.0;
+    return;
+  }
+
+  /*
+   * First, figure out z-coordinates for projection of P1 and P2 to
+   * deformed sphere
+   */
+  vset(p1, p1x, p1y, tb_project_to_sphere(TRACKBALLSIZE, p1x, p1y));
+  vset(p2, p2x, p2y, tb_project_to_sphere(TRACKBALLSIZE, p2x, p2y));
+
+  /*
+   *  Now, we want the cross product of P1 and P2
+   */
+  vcross(p2, p1, a);
+
+  /*
+   *  Figure out how much to rotate around that axis.
+   */
+  vsub(p1, p2, d);
+  t = vlength(d) / (2.0 * TRACKBALLSIZE);
+
+  /*
+   * Avoid problems with out-of-control values...
+   */
+  if (t > 1.0)
+    t = 1.0;
+  if (t < -1.0)
+    t = -1.0;
+  phi = 2.0 * asin(t);
+
+  axis_to_quat(a, phi, q);
+}
+
+/*
+ *  Given an axis and angle, compute quaternion.
+ */
+void axis_to_quat(float a[3], float phi, float q[4]) {
+  vnormal(a);
+  vcopy(a, q);
+  vscale(q, sin(phi / 2.0));
+  q[3] = cos(phi / 2.0);
+}
+
+/*
+ * Project an x,y pair onto a sphere of radius r OR a hyperbolic sheet
+ * if we are away from the center of the sphere.
+ */
+static float tb_project_to_sphere(float r, float x, float y) {
+  float d, t, z;
+
+  d = sqrt(x * x + y * y);
+  if (d < r * 0.70710678118654752440) { /* Inside sphere */
+    z = sqrt(r * r - d * d);
+  } else { /* On hyperbola */
+    t = r / 1.41421356237309504880;
+    z = t * t / d;
+  }
+  return z;
+}
+
+/*
+ * Given two rotations, e1 and e2, expressed as quaternion rotations,
+ * figure out the equivalent single rotation and stuff it into dest.
+ *
+ * This routine also normalizes the result every RENORMCOUNT times it is
+ * called, to keep error from creeping in.
+ *
+ * NOTE: This routine is written so that q1 or q2 may be the same
+ * as dest (or each other).
+ */
+
+#define RENORMCOUNT 97
+
+void add_quats(float q1[4], float q2[4], float dest[4]) {
+  static int count = 0;
+  float t1[4], t2[4], t3[4];
+  float tf[4];
+
+  vcopy(q1, t1);
+  vscale(t1, q2[3]);
+
+  vcopy(q2, t2);
+  vscale(t2, q1[3]);
+
+  vcross(q2, q1, t3);
+  vadd(t1, t2, tf);
+  vadd(t3, tf, tf);
+  tf[3] = q1[3] * q2[3] - vdot(q1, q2);
+
+  dest[0] = tf[0];
+  dest[1] = tf[1];
+  dest[2] = tf[2];
+  dest[3] = tf[3];
+
+  if (++count > RENORMCOUNT) {
+    count = 0;
+    normalize_quat(dest);
+  }
+}
+
+/*
+ * Quaternions always obey:  a^2 + b^2 + c^2 + d^2 = 1.0
+ * If they don't add up to 1.0, dividing by their magnitued will
+ * renormalize them.
+ *
+ * Note: See the following for more information on quaternions:
+ *
+ * - Shoemake, K., Animating rotation with quaternion curves, Computer
+ *   Graphics 19, No 3 (Proc. SIGGRAPH'85), 245-254, 1985.
+ * - Pletinckx, D., Quaternion calculus as a basic tool in computer
+ *   graphics, The Visual Computer 5, 2-13, 1989.
+ */
+static void normalize_quat(float q[4]) {
+  int i;
+  float mag;
+
+  mag = (q[0] * q[0] + q[1] * q[1] + q[2] * q[2] + q[3] * q[3]);
+  for (i = 0; i < 4; i++)
+    q[i] /= mag;
+}
+
+/*
+ * Build a rotation matrix, given a quaternion rotation.
+ *
+ */
+void build_rotmatrix(float m[4][4], const float q[4]) {
+  m[0][0] = 1.0 - 2.0 * (q[1] * q[1] + q[2] * q[2]);
+  m[0][1] = 2.0 * (q[0] * q[1] - q[2] * q[3]);
+  m[0][2] = 2.0 * (q[2] * q[0] + q[1] * q[3]);
+  m[0][3] = 0.0;
+
+  m[1][0] = 2.0 * (q[0] * q[1] + q[2] * q[3]);
+  m[1][1] = 1.0 - 2.0 * (q[2] * q[2] + q[0] * q[0]);
+  m[1][2] = 2.0 * (q[1] * q[2] - q[0] * q[3]);
+  m[1][3] = 0.0;
+
+  m[2][0] = 2.0 * (q[2] * q[0] - q[1] * q[3]);
+  m[2][1] = 2.0 * (q[1] * q[2] + q[0] * q[3]);
+  m[2][2] = 1.0 - 2.0 * (q[1] * q[1] + q[0] * q[0]);
+  m[2][3] = 0.0;
+
+  m[3][0] = 0.0;
+  m[3][1] = 0.0;
+  m[3][2] = 0.0;
+  m[3][3] = 1.0;
+}
diff --git a/examples/viewer/trackball.h b/examples/viewer/trackball.h
new file mode 100644
index 0000000..b1f9437
--- /dev/null
+++ b/examples/viewer/trackball.h
@@ -0,0 +1,75 @@
+/*
+ * (c) Copyright 1993, 1994, Silicon Graphics, Inc.
+ * ALL RIGHTS RESERVED
+ * Permission to use, copy, modify, and distribute this software for
+ * any purpose and without fee is hereby granted, provided that the above
+ * copyright notice appear in all copies and that both the copyright notice
+ * and this permission notice appear in supporting documentation, and that
+ * the name of Silicon Graphics, Inc. not be used in advertising
+ * or publicity pertaining to distribution of the software without specific,
+ * written prior permission.
+ *
+ * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
+ * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
+ * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
+ * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
+ * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
+ * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
+ * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
+ * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
+ * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
+ * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * US Government Users Restricted Rights
+ * Use, duplication, or disclosure by the Government is subject to
+ * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
+ * (c)(1)(ii) of the Rights in Technical Data and Computer Software
+ * clause at DFARS 252.227-7013 and/or in similar or successor
+ * clauses in the FAR or the DOD or NASA FAR Supplement.
+ * Unpublished-- rights reserved under the copyright laws of the
+ * United States.  Contractor/manufacturer is Silicon Graphics,
+ * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
+ *
+ * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
+ */
+/*
+ * trackball.h
+ * A virtual trackball implementation
+ * Written by Gavin Bell for Silicon Graphics, November 1988.
+ */
+
+/*
+ * Pass the x and y coordinates of the last and current positions of
+ * the mouse, scaled so they are from (-1.0 ... 1.0).
+ *
+ * The resulting rotation is returned as a quaternion rotation in the
+ * first paramater.
+ */
+void trackball(float q[4], float p1x, float p1y, float p2x, float p2y);
+
+void negate_quat(float *q, float *qn);
+
+/*
+ * Given two quaternions, add them together to get a third quaternion.
+ * Adding quaternions to get a compound rotation is analagous to adding
+ * translations to get a compound translation.  When incrementally
+ * adding rotations, the first argument here should be the new
+ * rotation, the second and third the total rotation (which will be
+ * over-written with the resulting new total rotation).
+ */
+void add_quats(float *q1, float *q2, float *dest);
+
+/*
+ * A useful function, builds a rotation matrix in Matrix based on
+ * given quaternion.
+ */
+void build_rotmatrix(float m[4][4], const float q[4]);
+
+/*
+ * This function computes a quaternion based on an axis (defined by
+ * the given vector) and an angle about which to rotate.  The angle is
+ * expressed in radians.  The result is put into the third argument.
+ */
+void axis_to_quat(float a[3], float phi, float q[4]);
diff --git a/examples/viewer/viewer.cc b/examples/viewer/viewer.cc
new file mode 100644
index 0000000..d89fadc
--- /dev/null
+++ b/examples/viewer/viewer.cc
@@ -0,0 +1,403 @@
+//
+// Simple .obj viewer(vertex only)
+//
+#include <vector>
+#include <string>
+#include <cstdio>
+#include <iostream>
+#include <limits>
+#include <cmath>
+
+#include <GL/glew.h>
+
+#ifdef __APPLE__
+#include <OpenGL/glu.h>
+#else
+#include <GL/glu.h>
+#endif
+
+#include <GLFW/glfw3.h>
+
+#include "../../tiny_obj_loader.h"
+
+#include "trackball.h"
+
+typedef struct {
+  GLuint vb;    // vertex buffer
+  int numTriangles;
+} DrawObject;
+
+std::vector<DrawObject> gDrawObjects;
+
+int width = 512;
+int height = 512;
+
+double prevMouseX, prevMouseY;
+bool mouseLeftPressed;
+bool mouseMiddlePressed;
+bool mouseRightPressed;
+float curr_quat[4];
+float prev_quat[4];
+float eye[3], lookat[3], up[3];
+
+GLFWwindow* window;
+
+void CheckErrors(std::string desc) {
+  GLenum e = glGetError();
+  if (e != GL_NO_ERROR) {
+    fprintf(stderr, "OpenGL error in \"%s\": %d (%d)\n", desc.c_str(), e, e);
+    exit(20);
+  }
+}
+
+void CalcNormal(float N[3], float v0[3], float v1[3], float v2[3]) {
+  float v10[3];
+  v10[0] = v1[0] - v0[0];
+  v10[1] = v1[1] - v0[1];
+  v10[2] = v1[2] - v0[2];
+
+  float v20[3];
+  v20[0] = v2[0] - v0[0];
+  v20[1] = v2[1] - v0[1];
+  v20[2] = v2[2] - v0[2];
+
+  N[0] = v20[1] * v10[2] - v20[2] * v10[1];
+  N[1] = v20[2] * v10[0] - v20[0] * v10[2];
+  N[2] = v20[0] * v10[1] - v20[1] * v10[0];
+
+  float len2 = N[0] * N[0] + N[1] * N[1] + N[2] * N[2];
+  if (len2 > 0.0f) {
+    float len = sqrtf(len2);
+    
+    N[0] /= len;
+    N[1] /= len;
+  }
+}
+
+bool LoadObjAndConvert(float bmin[3], float bmax[3], std::vector<DrawObject>& drawObjects, const char* filename)
+{
+  tinyobj::attrib_t attrib;
+  std::vector<tinyobj::shape_t> shapes;
+  std::vector<tinyobj::material_t> materials;
+  
+  std::string err;
+  bool ret = tinyobj::LoadObj(&attrib, &shapes, &materials, &err, filename, NULL);
+  if (!err.empty()) {
+    std::cerr << err << std::endl;
+  }
+
+  if (!ret) {
+    std::cerr << "Failed to load " << filename << std::endl;
+    return false;
+  }
+
+  printf("# of materials = %d\n", (int)materials.size());
+  printf("# of shapes = %d\n", (int)shapes.size());
+
+  bmin[0] = bmin[1] = bmin[2] = std::numeric_limits<float>::max();
+  bmax[0] = bmax[1] = bmax[2] = -std::numeric_limits<float>::max();
+
+  {
+      for (size_t s = 0; s < shapes.size(); s++) {
+        DrawObject o;
+        std::vector<float> vb; // pos(3float), normal(3float)
+        for (size_t f = 0; f < shapes[s].mesh.indices.size()/3; f++) {
+
+          tinyobj::index_t idx0 = shapes[s].mesh.indices[3*f+0];
+          tinyobj::index_t idx1 = shapes[s].mesh.indices[3*f+1];
+          tinyobj::index_t idx2 = shapes[s].mesh.indices[3*f+2];
+
+          float v[3][3];
+          for (int k = 0; k < 3; k++) {
+            int f0 = idx0.vertex_index;
+            int f1 = idx1.vertex_index;
+            int f2 = idx2.vertex_index;
+
+            v[0][k] = attrib.vertices[3*f0+k];
+            v[1][k] = attrib.vertices[3*f1+k];
+            v[2][k] = attrib.vertices[3*f2+k];
+            bmin[k] = std::min(v[0][k], bmin[k]);
+            bmin[k] = std::min(v[1][k], bmin[k]);
+            bmin[k] = std::min(v[2][k], bmin[k]);
+            bmax[k] = std::max(v[0][k], bmax[k]);
+            bmax[k] = std::max(v[1][k], bmax[k]);
+            bmax[k] = std::max(v[2][k], bmax[k]);
+          }
+
+          float n[3][3];
+
+          if (attrib.normals.size() > 0) { 
+            int f0 = idx0.normal_index;
+            int f1 = idx1.normal_index;
+            int f2 = idx2.normal_index;
+            for (int k = 0; k < 3; k++) {
+              n[0][k] = attrib.normals[3*f0+k];
+              n[1][k] = attrib.normals[3*f1+k];
+              n[2][k] = attrib.normals[3*f2+k];
+            }
+          } else {
+            // compute geometric normal
+            CalcNormal(n[0], v[0], v[1], v[2]);
+            n[1][0] = n[0][0]; n[1][1] = n[0][1]; n[1][2] = n[0][2];
+            n[2][0] = n[0][0]; n[2][1] = n[0][1]; n[2][2] = n[0][2];
+          }
+
+          for (int k = 0; k < 3; k++) {
+            vb.push_back(v[k][0]);
+            vb.push_back(v[k][1]);
+            vb.push_back(v[k][2]);
+            vb.push_back(n[k][0]);
+            vb.push_back(n[k][1]);
+            vb.push_back(n[k][2]);
+          }
+          
+        }
+
+        o.vb = 0;
+        o.numTriangles = 0;
+        if (vb.size() > 0) {
+          glGenBuffers(1, &o.vb);
+          glBindBuffer(GL_ARRAY_BUFFER, o.vb);
+          glBufferData(GL_ARRAY_BUFFER, vb.size() * sizeof(float), &vb.at(0), GL_STATIC_DRAW);
+          o.numTriangles = vb.size() / 6 / 3;
+        }
+
+        gDrawObjects.push_back(o);
+    }
+  }
+  
+  printf("bmin = %f, %f, %f\n", bmin[0], bmin[1], bmin[2]);
+  printf("bmax = %f, %f, %f\n", bmax[0], bmax[1], bmax[2]);
+
+  return true;
+}
+
+void reshapeFunc(GLFWwindow* window, int w, int h)
+{
+  printf("reshape\n");
+  glViewport(0, 0, w, h);
+  glMatrixMode(GL_PROJECTION);
+  glLoadIdentity();
+  gluPerspective(45.0, (float)w / (float)h, 0.1f, 1000.0f);
+  glMatrixMode(GL_MODELVIEW);
+  glLoadIdentity();
+
+  width = w;
+  height = h;
+}
+
+void keyboardFunc(GLFWwindow *window, int key, int scancode, int action, int mods) {
+    if(action == GLFW_PRESS || action == GLFW_REPEAT){
+        // Move camera
+        float mv_x = 0, mv_y = 0, mv_z = 0;
+        if(key == GLFW_KEY_K) mv_x += 1;
+        else if(key == GLFW_KEY_J) mv_x += -1;
+        else if(key == GLFW_KEY_L) mv_y += 1;
+        else if(key == GLFW_KEY_H) mv_y += -1;
+        else if(key == GLFW_KEY_P) mv_z += 1;
+        else if(key == GLFW_KEY_N) mv_z += -1;
+        //camera.move(mv_x * 0.05, mv_y * 0.05, mv_z * 0.05);
+        // Close window
+        if(key == GLFW_KEY_Q || key == GLFW_KEY_ESCAPE) glfwSetWindowShouldClose(window, GL_TRUE);
+
+        //init_frame = true;
+    }
+}
+
+void clickFunc(GLFWwindow* window, int button, int action, int mods){
+    if(button == GLFW_MOUSE_BUTTON_LEFT){
+        if(action == GLFW_PRESS){
+            mouseLeftPressed = true;
+            trackball(prev_quat, 0.0, 0.0, 0.0, 0.0);
+        } else if(action == GLFW_RELEASE){
+            mouseLeftPressed = false;
+        }
+    }
+    if(button == GLFW_MOUSE_BUTTON_RIGHT){
+        if(action == GLFW_PRESS){
+            mouseRightPressed = true;
+        } else if(action == GLFW_RELEASE){
+            mouseRightPressed = false;
+        }
+    }
+    if(button == GLFW_MOUSE_BUTTON_MIDDLE){
+        if(action == GLFW_PRESS){
+            mouseMiddlePressed = true;
+        } else if(action == GLFW_RELEASE){
+            mouseMiddlePressed = false;
+        }
+    }
+}
+
+void motionFunc(GLFWwindow* window, double mouse_x, double mouse_y){
+  float rotScale = 1.0f;
+  float transScale = 2.0f;
+
+    if(mouseLeftPressed){
+      trackball(prev_quat,
+          rotScale * (2.0f * prevMouseX - width) / (float)width,
+          rotScale * (height - 2.0f * prevMouseY) / (float)height,
+          rotScale * (2.0f * mouse_x - width) / (float)width,
+          rotScale * (height - 2.0f * mouse_y) / (float)height);
+
+      add_quats(prev_quat, curr_quat, curr_quat);
+    } else if (mouseMiddlePressed) {
+      eye[0] += transScale * (mouse_x - prevMouseX) / (float)width;
+      lookat[0] += transScale * (mouse_x - prevMouseX) / (float)width;
+      eye[1] += transScale * (mouse_y - prevMouseY) / (float)height;
+      lookat[1] += transScale * (mouse_y - prevMouseY) / (float)height;
+    } else if (mouseRightPressed) {
+      eye[2] += transScale * (mouse_y - prevMouseY) / (float)height;
+      lookat[2] += transScale * (mouse_y - prevMouseY) / (float)height;
+    }
+
+    // Update mouse point
+    prevMouseX = mouse_x;
+    prevMouseY = mouse_y;
+}
+
+void Draw(const std::vector<DrawObject>& drawObjects)
+{
+  glPolygonMode(GL_FRONT, GL_FILL);
+  glPolygonMode(GL_BACK, GL_FILL);
+
+  glEnable(GL_POLYGON_OFFSET_FILL);
+  glPolygonOffset(1.0, 1.0);
+  glColor3f(1.0f, 1.0f, 1.0f);
+  for (size_t i = 0; i < drawObjects.size(); i++) {
+    DrawObject o = drawObjects[i];
+    if (o.vb < 1) {
+      continue;
+    }
+ 
+    glBindBuffer(GL_ARRAY_BUFFER, o.vb);
+    glEnableClientState(GL_VERTEX_ARRAY);
+    glEnableClientState(GL_NORMAL_ARRAY);
+    glVertexPointer(3, GL_FLOAT, 24, (const void*)0);
+    glNormalPointer(GL_FLOAT, 24, (const void*)(sizeof(float)*3));
+
+    glDrawArrays(GL_TRIANGLES, 0, 3 * o.numTriangles);
+    CheckErrors("drawarrays");
+  }
+
+  // draw wireframe
+  glDisable(GL_POLYGON_OFFSET_FILL);
+  glPolygonMode(GL_FRONT, GL_LINE);
+  glPolygonMode(GL_BACK, GL_LINE);
+
+  glColor3f(0.0f, 0.0f, 0.4f);
+  for (size_t i = 0; i < drawObjects.size(); i++) {
+    DrawObject o = drawObjects[i];
+    if (o.vb < 1) {
+      continue;
+    }
+ 
+    glBindBuffer(GL_ARRAY_BUFFER, o.vb);
+    glEnableClientState(GL_VERTEX_ARRAY);
+    glEnableClientState(GL_NORMAL_ARRAY);
+    glVertexPointer(3, GL_FLOAT, 24, (const void*)0);
+    glNormalPointer(GL_FLOAT, 24, (const void*)(sizeof(float)*3));
+
+    glDrawArrays(GL_TRIANGLES, 0, 3 * o.numTriangles);
+    CheckErrors("drawarrays");
+  }
+}
+
+static void Init() {
+  trackball(curr_quat, 0, 0, 0, 0);
+
+  eye[0] = 0.0f;
+  eye[1] = 0.0f;
+  eye[2] = 3.0f;
+
+  lookat[0] = 0.0f;
+  lookat[1] = 0.0f;
+  lookat[2] = 0.0f;
+
+  up[0] = 0.0f;
+  up[1] = 1.0f;
+  up[2] = 0.0f;
+}
+
+
+int main(int argc, char **argv)
+{
+  if (argc < 2) {
+    std::cout << "Needs input.obj\n" << std::endl;
+    return 0;
+  }
+
+  Init();
+ 
+
+  if(!glfwInit()){
+    std::cerr << "Failed to initialize GLFW." << std::endl;
+    return -1;
+  }
+
+  
+
+  window = glfwCreateWindow(width, height, "Obj viewer", NULL, NULL);
+  if(window == NULL){
+    std::cerr << "Failed to open GLFW window. " << std::endl;
+    glfwTerminate();
+    return 1;
+  }
+
+  glfwMakeContextCurrent(window);
+
+  // Callback
+  glfwSetWindowSizeCallback(window, reshapeFunc);
+  glfwSetKeyCallback(window, keyboardFunc);
+  glfwSetMouseButtonCallback(window, clickFunc);
+  glfwSetCursorPosCallback(window, motionFunc);
+
+  glewExperimental = true;
+  if (glewInit() != GLEW_OK) {
+    std::cerr << "Failed to initialize GLEW." << std::endl;
+    return -1;
+  }
+
+  reshapeFunc(window, width, height);
+
+  float bmin[3], bmax[3];
+  if (false == LoadObjAndConvert(bmin, bmax, gDrawObjects, argv[1])) {
+    return -1;
+  }
+
+  float maxExtent = 0.5f * (bmax[0] - bmin[0]);
+  if (maxExtent < 0.5f * (bmax[1] - bmin[1])) {
+    maxExtent = 0.5f * (bmax[1] - bmin[1]);
+  }
+  if (maxExtent < 0.5f * (bmax[2] - bmin[2])) {
+    maxExtent = 0.5f * (bmax[2] - bmin[2]);
+  }
+
+  while(glfwWindowShouldClose(window) == GL_FALSE) {
+    glfwPollEvents();
+    glClearColor(0.1f, 0.2f, 0.3f, 1.0f);
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    glEnable(GL_DEPTH_TEST);
+
+    // camera & rotate
+    glMatrixMode(GL_MODELVIEW);
+    glLoadIdentity();
+    GLfloat mat[4][4];
+    gluLookAt(eye[0], eye[1], eye[2], lookat[0], lookat[1], lookat[2], up[0], up[1], up[2]);
+    build_rotmatrix(mat, curr_quat);
+    glMultMatrixf(&mat[0][0]);
+
+    // Fit to -1, 1
+    glScalef(1.0f / maxExtent, 1.0f / maxExtent, 1.0f / maxExtent);
+
+    // Centerize object.
+    glTranslatef(-0.5*(bmax[0] + bmin[0]), -0.5*(bmax[1] + bmin[1]), -0.5*(bmax[2] + bmin[2]));
+  
+    Draw(gDrawObjects);
+
+    glfwSwapBuffers(window);
+  }
+
+  glfwTerminate();
+}