libigl_Martin/examples/skeleton-builder/example.cpp

#include <igl/draw_skeleton_3d.h>
#include <igl/draw_skeleton_vector_graphics.h>
#include <igl/two_axis_valuator_fixed_up.h>
#include <igl/read_triangle_mesh.h>
#include <igl/readTGF.h>
#include <igl/writeOBJ.h>
#include <igl/writeOFF.h>
#include <igl/report_gl_error.h>
#include <igl/draw_mesh.h>
#include <igl/draw_floor.h>
#include <igl/pathinfo.h>
#include <igl/list_to_matrix.h>
#include <igl/quat_to_mat.h>
#include <igl/per_face_normals.h>
#include <igl/material_colors.h>
#include <igl/trackball.h>
#include <igl/snap_to_canonical_view_quat.h>
#include <igl/snap_to_fixed_up.h>
#include <igl/REDRUM.h>
#include <igl/Camera.h>
#include <igl/ReAntTweakBar.h>
#include <igl/get_seconds.h>
#include <igl/forward_kinematics.h>
#include <igl/boundary_conditions.h>
#include <igl/normalize_row_sums.h>
#include <igl/lbs_matrix.h>
#include <igl/sort_triangles.h>
#include <igl/slice.h>
#include <igl/project.h>
#include <igl/unproject.h>
#include <igl/embree/EmbreeIntersector.h>
#include <igl/embree/unproject_in_mesh.h>
#include <igl/matlab_format.h>
#include <igl/remove_unreferenced.h>
#include <igl/adjacency_list.h>
#include <igl/adjacency_matrix.h>
#include <igl/right_axis.h>
#include <igl/colon.h>
#include <igl/unique.h>
#include <igl/REDRUM.h>
#include <igl/writeTGF.h>
#include <igl/file_exists.h>
#include <igl/centroid.h>

#include <Eigen/Core>
#include <Eigen/Geometry>

#ifdef __APPLE__
#include <GLUT/glut.h>
#include <Carbon/Carbon.h>
#else
#include <GL/glut.h>
#endif

#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <iostream>

enum SkelStyleType
{
  SKEL_STYLE_TYPE_3D = 0,
  SKEL_STYLE_TYPE_VECTOR_GRAPHICS = 1,
  NUM_SKEL_STYLE_TYPE = 2
}skel_style;

Eigen::MatrixXd V,N,sorted_N;
Eigen::Vector3d Vmid,Vcen;
double bbd = 1.0;
Eigen::MatrixXi F,sorted_F;
Eigen::VectorXi P;
igl::Camera camera;
struct State
{
  Eigen::MatrixXd C;
  Eigen::MatrixXi BE;
  Eigen::VectorXi sel;
} s;

bool wireframe = false;
bool skeleton_on_top = false;
double alpha = 0.5;

// See README for descriptions
enum RotationType
{
  ROTATION_TYPE_IGL_TRACKBALL = 0,
  ROTATION_TYPE_TWO_AXIS_VALUATOR_FIXED_UP = 1,
  NUM_ROTATION_TYPES = 2,
} rotation_type = ROTATION_TYPE_TWO_AXIS_VALUATOR_FIXED_UP;

std::stack<State> undo_stack;
std::stack<State> redo_stack;

bool is_rotating = false;
bool is_dragging = false;
bool new_leaf_on_drag = false;
bool new_root_on_drag = false;
int down_x,down_y;
Eigen::MatrixXd down_C;
igl::Camera down_camera;
std::string output_filename;

bool is_animating = false;
double animation_start_time = 0;
double ANIMATION_DURATION = 0.5;
Eigen::Quaterniond animation_from_quat;
Eigen::Quaterniond animation_to_quat;

int width,height;
Eigen::Vector4f light_pos(-0.1,-0.1,0.9,0);

#define REBAR_NAME "temp.rbr"
igl::ReTwBar rebar;
igl::EmbreeIntersector ei;

void push_undo()
{
  undo_stack.push(s);
  // Clear
  redo_stack = std::stack<State>();
}

// No-op setter, does nothing
void TW_CALL no_op(const void * /*value*/, void * /*clientData*/)
{
}

void TW_CALL set_rotation_type(const void * value, void * clientData)
{
  using namespace Eigen;
  using namespace std;
  using namespace igl;
  const RotationType old_rotation_type = rotation_type;
  rotation_type = *(const RotationType *)(value);
  if(rotation_type == ROTATION_TYPE_TWO_AXIS_VALUATOR_FIXED_UP &&
    old_rotation_type != ROTATION_TYPE_TWO_AXIS_VALUATOR_FIXED_UP)
  {
    push_undo();
    animation_from_quat = camera.m_rotation_conj;
    snap_to_fixed_up(animation_from_quat,animation_to_quat);
    // start animation
    animation_start_time = get_seconds();
    is_animating = true;
  }
}
void TW_CALL get_rotation_type(void * value, void *clientData)
{
  RotationType * rt = (RotationType *)(value);
  *rt = rotation_type;
}

void reshape(int width, int height)
{
  ::width = width;
  ::height = height;
  glViewport(0,0,width,height);
  // Send the new window size to AntTweakBar
  TwWindowSize(width, height);
  camera.m_aspect = (double)width/(double)height;
}

void push_scene()
{
  using namespace igl;
  using namespace std;
  glMatrixMode(GL_PROJECTION);
  glPushMatrix();
  glLoadIdentity();
  gluPerspective(camera.m_angle,camera.m_aspect,camera.m_near,camera.m_far);
  glMatrixMode(GL_MODELVIEW);
  glPushMatrix();
  glLoadIdentity();
  gluLookAt(
    camera.eye()(0), camera.eye()(1), camera.eye()(2),
    camera.at()(0), camera.at()(1), camera.at()(2),
    camera.up()(0), camera.up()(1), camera.up()(2));
}

void push_object()
{
  using namespace igl;
  glPushMatrix();
  glScaled(2./bbd,2./bbd,2./bbd);
  glTranslated(-Vmid(0),-Vmid(1),-Vmid(2));
}

void pop_object()
{
  glPopMatrix();
}

void pop_scene()
{
  glMatrixMode(GL_PROJECTION);
  glPopMatrix();
  glMatrixMode(GL_MODELVIEW);
  glPopMatrix();
}

// Set up double-sided lights
void lights()
{
  using namespace std;
  using namespace Eigen;
  glEnable(GL_LIGHTING);
  glLightModelf(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE);
  glEnable(GL_LIGHT0);
  glEnable(GL_LIGHT1);
  float WHITE[4] =  {0.8,0.8,0.8,1.};
  float GREY[4] =  {0.4,0.4,0.4,1.};
  float BLACK[4] =  {0.,0.,0.,1.};
  Vector4f pos = light_pos;
  glLightfv(GL_LIGHT0,GL_AMBIENT,GREY);
  glLightfv(GL_LIGHT0,GL_DIFFUSE,WHITE);
  glLightfv(GL_LIGHT0,GL_SPECULAR,BLACK);
  glLightfv(GL_LIGHT0,GL_POSITION,pos.data());
  pos(0) *= -1;
  pos(1) *= -1;
  pos(2) *= -1;
  glLightfv(GL_LIGHT1,GL_AMBIENT,GREY);
  glLightfv(GL_LIGHT1,GL_DIFFUSE,WHITE);
  glLightfv(GL_LIGHT1,GL_SPECULAR,BLACK);
  glLightfv(GL_LIGHT1,GL_POSITION,pos.data());
}

void sort()
{
  using namespace std;
  using namespace Eigen;
  using namespace igl;
  push_scene();
  push_object();
  VectorXi I;
  sort_triangles(V,F,sorted_F,I);
  slice(N,I,1,sorted_N);
  pop_object();
  pop_scene();
}

void display()
{
  using namespace igl;
  using namespace std;
  using namespace Eigen;
  const float back[4] = {0.75, 0.75, 0.75,0};
  glClearColor(back[0],back[1],back[2],0);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  static bool first = true;
  if(first)
  {
    sort();
    first = false;
  }

  if(is_animating)
  {
    double t = (get_seconds() - animation_start_time)/ANIMATION_DURATION;
    if(t > 1)
    {
      t = 1;
      is_animating = false;
    }
    Quaterniond q = animation_from_quat.slerp(t,animation_to_quat).normalized();
    camera.orbit(q.conjugate());
  }

  glEnable(GL_DEPTH_TEST);
  glDepthFunc(GL_LEQUAL);
  glEnable(GL_NORMALIZE);
  glEnable(GL_BLEND);
  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  lights();
  push_scene();

  // Draw a nice floor
  glEnable(GL_DEPTH_TEST);
  glPushMatrix();
  const double floor_offset =
    -2./bbd*(V.col(1).maxCoeff()-Vmid(1));
  glTranslated(0,floor_offset,0);
  const float GREY[4] = {0.5,0.5,0.6,1.0};
  const float DARK_GREY[4] = {0.2,0.2,0.3,1.0};
  glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
  glEnable(GL_CULL_FACE);
  glCullFace(GL_BACK);
  draw_floor(GREY,DARK_GREY);
  glDisable(GL_CULL_FACE);
  glPopMatrix();

  push_object();

  const auto & draw_skeleton = []()
  {
    switch(skel_style)
    {
      default:
      case SKEL_STYLE_TYPE_3D:
      {
        MatrixXf colors = MAYA_VIOLET.transpose().replicate(s.BE.rows(),1);
        for(int si=0;si<s.sel.size();si++)
        {
          for(int b=0;b<s.BE.rows();b++)
          {
            if(s.BE(b,0) == s.sel(si) || s.BE(b,1) == s.sel(si))
            {
              colors.row(b) = MAYA_SEA_GREEN;
            }
          }
        }
        draw_skeleton_3d(s.C,s.BE,MatrixXd(),colors);
        break;
      }
      case SKEL_STYLE_TYPE_VECTOR_GRAPHICS:
        draw_skeleton_vector_graphics(s.C,s.BE);
        break;
    }
  };
  
  if(!skeleton_on_top)
  {
    draw_skeleton();
  }

  // Set material properties
  glDisable(GL_COLOR_MATERIAL);
  glMaterialfv(GL_FRONT, GL_AMBIENT,
    Vector4f(GOLD_AMBIENT[0],GOLD_AMBIENT[1],GOLD_AMBIENT[2],alpha).data());
  glMaterialfv(GL_FRONT, GL_DIFFUSE,
    Vector4f(GOLD_DIFFUSE[0],GOLD_DIFFUSE[1],GOLD_DIFFUSE[2],alpha).data());
  glMaterialfv(GL_FRONT, GL_SPECULAR,
    Vector4f(GOLD_SPECULAR[0],GOLD_SPECULAR[1],GOLD_SPECULAR[2],alpha).data());
  glMaterialf (GL_FRONT, GL_SHININESS, 128);
  glMaterialfv(GL_BACK, GL_AMBIENT,
    Vector4f(SILVER_AMBIENT[0],SILVER_AMBIENT[1],SILVER_AMBIENT[2],alpha).data());
  glMaterialfv(GL_BACK, GL_DIFFUSE,
    Vector4f(FAST_GREEN_DIFFUSE[0],FAST_GREEN_DIFFUSE[1],FAST_GREEN_DIFFUSE[2],alpha).data());
  glMaterialfv(GL_BACK, GL_SPECULAR,
    Vector4f(SILVER_SPECULAR[0],SILVER_SPECULAR[1],SILVER_SPECULAR[2],alpha).data());
  glMaterialf (GL_BACK, GL_SHININESS, 128);

  if(wireframe)
  {
    glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);
  }
  glLineWidth(1.0);
  draw_mesh(V,sorted_F,sorted_N);
  glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);

  if(skeleton_on_top)
  {
    glDisable(GL_DEPTH_TEST);
    draw_skeleton();
  }

  pop_object();
  pop_scene();

  report_gl_error();

  TwDraw();
  glutSwapBuffers();
  if(is_animating)
  {
    glutPostRedisplay();
  }
}

void mouse_wheel(int wheel, int direction, int mouse_x, int mouse_y)
{
  using namespace std;
  using namespace igl;
  using namespace Eigen;
  GLint viewport[4];
  glGetIntegerv(GL_VIEWPORT,viewport);
  if(wheel == 0 && TwMouseMotion(mouse_x, viewport[3] - mouse_y))
  {
    static double mouse_scroll_y = 0;
    const double delta_y = 0.125*direction;
    mouse_scroll_y += delta_y;
    TwMouseWheel(mouse_scroll_y);
    return;
  }
  push_undo();

  if(wheel==0)
  {
    // factor of zoom change
    double s = (1.-0.01*direction);
    //// FOV zoom: just widen angle. This is hardly ever appropriate.
    //camera.m_angle *= s;
    //camera.m_angle = min(max(camera.m_angle,1),89);
    camera.push_away(s);
  }else
  {
    // Dolly zoom:
    camera.dolly_zoom((double)direction*1.0);
  }
  glutPostRedisplay();
}

Eigen::VectorXi selection(const std::vector<bool> & mask)
{
  const int count = std::count(mask.begin(),mask.end(),true);
  Eigen::VectorXi sel(count);
  int s = 0;
  for(int c = 0;c<(int)mask.size();c++)
  {
    if(mask[c])
    {
      sel(s) = c;
      s++;
    }
  }
  return sel;
}

std::vector<bool> selection_mask(const Eigen::VectorXi & sel, const int n)
{
  std::vector<bool> mask(n,false);
  for(int si = 0;si<sel.size();si++)
  {
    const int i = sel(si);
    mask[i] = true;
  }
  return mask;
}

bool ss_select(
  const double mouse_x, 
  const double mouse_y,
  const Eigen::MatrixXd & C,
  const bool accum,
  Eigen::VectorXi & sel)
{
  using namespace igl;
  using namespace Eigen;
  using namespace std;
  //// zap old list
  //if(!accum)
  //{
  //  sel.resize(0,1);
  //}

  vector<bool> old_mask = selection_mask(s.sel,s.C.rows());
  vector<bool> mask(old_mask.size(),false);

  double min_dist = 1e25;
  bool sel_changed = false;
  bool found = false;
  for(int c = 0;c<C.rows();c++)
  {
    const RowVector3d & Cc = C.row(c);
    const auto Pc = project(Cc);
    const double SELECTION_DIST = 18;//pixels
    const double dist = (Pc.head(2)-RowVector2d(mouse_x,height-mouse_y)).norm();
    if(dist < SELECTION_DIST && (accum || dist < min_dist))
    {
      mask[c] = true;
      min_dist = dist;
      found = true;
      sel_changed |= mask[c] != old_mask[c];
    }
  }
  for(int c = 0;c<C.rows();c++)
  {
    if(accum)
    {
      mask[c] = mask[c] ^ old_mask[c];
    }else
    {
      if(!sel_changed)
      {
        mask[c] = mask[c] || old_mask[c];
      }
    }
  }
  sel = selection(mask);
  return found;
}

void mouse(int glutButton, int glutState, int mouse_x, int mouse_y)
{
  using namespace std;
  using namespace Eigen;
  using namespace igl;
  bool tw_using = TwEventMouseButtonGLUT(glutButton,glutState,mouse_x,mouse_y);
  const int mod = (glutButton <=2 ? glutGetModifiers() : 0);
  const bool option_down = mod & GLUT_ACTIVE_ALT;
  const bool shift_down = mod & GLUT_ACTIVE_SHIFT;
  const bool command_down = GLUT_ACTIVE_COMMAND & mod;
  switch(glutButton)
  {
    case GLUT_RIGHT_BUTTON:
    case GLUT_LEFT_BUTTON:
    {
      switch(glutState)
      {
        case 1:
          // up
          glutSetCursor(GLUT_CURSOR_INHERIT);
          if(is_rotating)
          {
            sort();
          }
          is_rotating = false;
          is_dragging = false;
          break;
        case 0:
          new_leaf_on_drag = false;
          new_root_on_drag = false;
          if(!tw_using)
          {
            down_x = mouse_x;
            down_y = mouse_y;
            if(option_down)
            {
              glutSetCursor(GLUT_CURSOR_CYCLE);
              // collect information for trackball
              is_rotating = true;
              down_camera = camera;
            }else
            {
              push_undo();
              push_scene();
              push_object();
              // Zap selection
              if(shift_down)
              {
                s.sel.resize(0,1);
              }
              if(ss_select(mouse_x,mouse_y,s.C,
                command_down && !shift_down,
                s.sel))
              {
                if(shift_down)
                {
                  new_leaf_on_drag = true;
                }
              }else
              {
                new_root_on_drag = true;
              }
              is_dragging = !command_down;
              down_C = s.C;
              pop_object();
              pop_scene();
            }
          }
        break;
      }
      break;
    }
    // Scroll down
    case 3:
    {
      mouse_wheel(0,-1,mouse_x,mouse_y);
      break;
    }
    // Scroll up
    case 4:
    {
      mouse_wheel(0,1,mouse_x,mouse_y);
      break;
    }
    // Scroll left
    case 5:
    {
      mouse_wheel(1,-1,mouse_x,mouse_y);
      break;
    }
    // Scroll right
    case 6:
    {
      mouse_wheel(1,1,mouse_x,mouse_y);
      break;
    }
  }
  glutPostRedisplay();
}

void mouse_drag(int mouse_x, int mouse_y)
{
  using namespace igl;
  using namespace std;
  using namespace Eigen;

  if(is_rotating)
  {
    glutSetCursor(GLUT_CURSOR_CYCLE);
    Quaterniond q;
    switch(rotation_type)
    {
      case ROTATION_TYPE_IGL_TRACKBALL:
      {
        // Rotate according to trackball
        igl::trackball<double>(
          width,
          height,
          2.0,
          down_camera.m_rotation_conj.coeffs().data(),
          down_x,
          down_y,
          mouse_x,
          mouse_y,
          q.coeffs().data());
          break;
      }
      case ROTATION_TYPE_TWO_AXIS_VALUATOR_FIXED_UP:
      {
        // Rotate according to two axis valuator with fixed up vector
        two_axis_valuator_fixed_up(
          width, height,
          2.0,
          down_camera.m_rotation_conj,
          down_x, down_y, mouse_x, mouse_y,
          q);
        break;
      }
      default:
        break;
    }
    camera.orbit(q.conjugate());
  }

  if(is_dragging)
  {
    push_scene();
    push_object();
    if(new_leaf_on_drag)
    {
      assert(s.C.size() >= 1);
      // one new node
      s.C.conservativeResize(s.C.rows()+1,3);
      const int nc = s.C.rows();
      assert(s.sel.size() >= 1);
      s.C.row(nc-1) = s.C.row(s.sel(0));
      // one new bone
      s.BE.conservativeResize(s.BE.rows()+1,2);
      s.BE.row(s.BE.rows()-1) = RowVector2i(s.sel(0),nc-1);
      // select just last node
      s.sel.resize(1,1);
      s.sel(0) = nc-1;
      // reset down_C
      down_C = s.C;
      new_leaf_on_drag = false;
    }
    if(new_root_on_drag)
    {
      // two new nodes
      s.C.conservativeResize(s.C.rows()+2,3);
      const int nc = s.C.rows();
      Vector3d obj;
      int nhits = unproject_in_mesh(mouse_x,height-mouse_y,ei,obj);
      if(nhits == 0)
      {
        Vector3d pV_mid = project(Vcen);
        obj = unproject(Vector3d(mouse_x,height-mouse_y,pV_mid(2)));
      }
      s.C.row(nc-2) = obj;
      s.C.row(nc-1) = obj;
      // select last node
      s.sel.resize(1,1);
      s.sel(0) = nc-1;
      // one new bone
      s.BE.conservativeResize(s.BE.rows()+1,2);
      s.BE.row(s.BE.rows()-1) = RowVector2i(nc-2,nc-1);
      // reset down_C
      down_C = s.C;
      new_root_on_drag = false;
    }
    double z = 0;
    Vector3d obj,win;
    int nhits = unproject_in_mesh(mouse_x,height-mouse_y,ei,obj);
    project(obj,win);
    z = win(2);

    for(int si = 0;si<s.sel.size();si++)
    {
      const int c = s.sel(si);
      Vector3d pc = project((RowVector3d) down_C.row(c));
      pc(0) += mouse_x-down_x;
      pc(1) += (height-mouse_y)-(height-down_y);
      if(nhits > 0)
      {
        pc(2) = z;
      }
      s.C.row(c) = unproject(pc);
    }
    pop_object();
    pop_scene();
  }

  glutPostRedisplay();
}

void init_relative()
{
  using namespace Eigen;
  using namespace igl;
  using namespace std;
  per_face_normals(V,F,N);
  const auto Vmax = V.colwise().maxCoeff();
  const auto Vmin = V.colwise().minCoeff();
  Vmid = 0.5*(Vmax + Vmin);
  centroid(V,F,Vcen);
  bbd = (Vmax-Vmin).norm();
  camera.push_away(2);
}

void undo()
{
  using namespace std;
  if(!undo_stack.empty())
  {
    redo_stack.push(s);
    s = undo_stack.top();
    undo_stack.pop();
  }
}

void redo()
{
  using namespace std;
  if(!redo_stack.empty())
  {
    undo_stack.push(s);
    s = redo_stack.top();
    redo_stack.pop();
  }
}

void symmetrize()
{
  using namespace std;
  using namespace igl;
  using namespace Eigen;
  if(s.sel.size() == 0)
  {
    cout<<YELLOWGIN("Make a selection first.")<<endl;
    return;
  }
  push_undo();
  push_scene();
  push_object();
  Vector3d right;
  right_axis(right.data(),right.data()+1,right.data()+2);
  right.normalize();
  MatrixXd RC(s.C.rows(),s.C.cols());
  MatrixXd old_C = s.C;
  for(int c = 0;c<s.C.rows();c++)
  {
    const Vector3d Cc = s.C.row(c);
    const auto A = Cc-Vcen;
    const auto A1 = A.dot(right) * right;
    const auto A2 = A-A1;
    RC.row(c) = Vcen + A2 - A1;
  }
  vector<bool> mask = selection_mask(s.sel,s.C.rows());
  // stupid O(n²) matching
  for(int c = 0;c<s.C.rows();c++)
  {
    // not selected
    if(!mask[c])
    {
      continue;
    }
    const Vector3d Cc = s.C.row(c);
    int min_r = -1;
    double min_dist = 1e25;
    double max_dist = 0.1*bbd;
    for(int r= 0;r<RC.rows();r++)
    {
      const Vector3d RCr = RC.row(r);
      const double dist = (Cc-RCr).norm();
      if(
          dist<min_dist &&  // closest
          dist<max_dist && // not too far away
          (c==r || (Cc-Vcen).dot(right)*(RCr-Vcen).dot(right) > 0) // on same side
        )
      {
        min_dist = dist;
        min_r = r;
      }
    }
    if(min_r>=0)
    {
      if(mask[min_r])
      {
        s.C.row(c) = 0.5*(Cc.transpose()+RC.row(min_r));
      }else
      {
        s.C.row(c) = RC.row(min_r);
      }
    }
  }
  pop_object();
  pop_scene();
}

bool save()
{
  using namespace std;
  using namespace igl;
  if(writeTGF(output_filename,s.C,s.BE))
  {
    cout<<GREENGIN("Current skeleton written to "+output_filename+".")<<endl;
    return true;
  }else
  {
    cout<<REDRUM("Writing to "+output_filename+" failed.")<<endl;
    return false;
  }
}

void key(unsigned char key, int mouse_x, int mouse_y)
{
  using namespace std;
  using namespace igl;
  using namespace Eigen;
  int mod = glutGetModifiers();
  const bool command_down = GLUT_ACTIVE_COMMAND & mod;
  const bool shift_down = GLUT_ACTIVE_SHIFT & mod;
  switch(key)
  {
    // ESC
    case char(27):
      rebar.save(REBAR_NAME);
    // ^C
    case char(3):
      exit(0);
    case char(127):
    {
      push_undo();
      // delete
      MatrixXi new_BE(s.BE.rows(),s.BE.cols());
      int count = 0;
      for(int b=0;b<s.BE.rows();b++)
      {
        bool selected = false;
        for(int si=0;si<s.sel.size();si++)
        {
          if(s.BE(b,0) == s.sel(si) || s.BE(b,1) == s.sel(si))
          {
            selected = true;
            break;
          }
        }
        if(!selected)
        {
          new_BE.row(count) = s.BE.row(b);
          count++;
        }
      }
      new_BE.conservativeResize(count,new_BE.cols());
      const auto old_C = s.C;
      VectorXi I;
      remove_unreferenced(old_C,new_BE,s.C,s.BE,I);
      s.sel.resize(0,1);
      break;
    }
    case 'A':
    case 'a':
    {
      push_undo();
      s.sel = colon<int>(0,s.C.rows()-1);
      break;
    }
    case 'C':
    case 'c':
    {
      push_undo();
      // snap close vertices
      SparseMatrix<double> A;
      adjacency_matrix(s.BE,A);
      VectorXi J = colon<int>(0,s.C.rows()-1);
      // stupid O(n²) version
      for(int c = 0;c<s.C.rows();c++)
      {
        for(int d = c+1;d<s.C.rows();d++)
        {
          if(
           A.coeff(c,d) == 0 &&  // no edge
           (s.C.row(c)-s.C.row(d)).norm() < 0.02*bbd //close
           )
          {
            // c < d
            J(d) = c;
          }
        }
      }
      for(int e = 0;e<s.BE.rows();e++)
      {
        s.BE(e,0) = J(s.BE(e,0));
        s.BE(e,1) = J(s.BE(e,1));
      }
      const auto old_BE = s.BE;
      const auto old_C = s.C;
      VectorXi I;
      remove_unreferenced(old_C,old_BE,s.C,s.BE,I);
      for(int i = 0;i<s.sel.size();i++)
      {
        s.sel(i) = J(s.sel(i));
      }
      VectorXi _;
      igl::unique(s.sel,s.sel,_,_);
      break;
    }
    case 'D':
    case 'd':
    {
      push_undo();
      s.sel.resize(0,1);
      break;
    }
    case 'P':
    case 'p':
    {
      // add bone to parents (should really only be one)
      push_undo();
      vector<int> new_sel;
      const int old_nbe = s.BE.rows();
      for(int si=0;si<s.sel.size();si++)
      {
        for(int b=0;b<old_nbe;b++)
        {
          if(s.BE(b,1) == s.sel(si))
          {
            // one new node
            s.C.conservativeResize(s.C.rows()+1,3);
            const int nc = s.C.rows();
            s.C.row(nc-1) = 0.5*(s.C.row(s.BE(b,1)) + s.C.row(s.BE(b,0)));
            // one new bone
            s.BE.conservativeResize(s.BE.rows()+1,2);
            s.BE.row(s.BE.rows()-1) = RowVector2i(nc-1,s.BE(b,1));
            s.BE(b,1) = nc-1;
            // select last node
            new_sel.push_back(nc-1);
          }
        }
      }
      list_to_matrix(new_sel,s.sel);
      break;
    }
    case 'R':
    case 'r':
    {
      // re-root try at first selected
      if(s.sel.size() > 0)
      {
        push_undo();
        // only use first
        s.sel.conservativeResize(1,1);
        // Ideally this should only effect the connected component of s.sel(0)
        const auto & C = s.C;
        auto & BE = s.BE;
        vector<bool> seen(C.rows(),false);
        // adjacency list
        vector<vector< int> > A;
        adjacency_list(BE,A,false);
        int e = 0;
        queue<int> Q;
        Q.push(s.sel(0));
        seen[s.sel(0)] = true;
        while(!Q.empty())
        {
          const int c = Q.front();
          Q.pop();
          for(const auto & d : A[c])
          {
            if(!seen[d])
            {
              BE(e,0) = c;
              BE(e,1) = d;
              e++;
              Q.push(d);
              seen[d] = true;
            }
          }
        }
        // only keep tree
        BE.conservativeResize(e,BE.cols());
      }
      break;
    }
    case 'S':
    case 's':
    {
      save();
      break;
    }
    case 'U':
    case 'u':
    {
      push_scene();
      push_object();
      for(int c = 0;c<s.C.rows();c++)
      {
        Vector3d P = project((Vector3d)s.C.row(c));
        Vector3d obj;
        int nhits = unproject_in_mesh(P(0),P(1),ei,obj);
        if(nhits > 0)
        {
          s.C.row(c) = obj;
        }
      }
      pop_object();
      pop_scene();
      break;
    }
    case 'Y':
    case 'y':
    {
      symmetrize();
      break;
    }
    case 'z':
    case 'Z':
      is_rotating = false;
      is_dragging = false;
      if(command_down)
      {
        if(shift_down)
        {
          redo();
        }else
        {
          undo();
        }
        break;
      }else
      {
        push_undo();
        Quaterniond q;
        snap_to_canonical_view_quat(camera.m_rotation_conj,1.0,q);
        camera.orbit(q.conjugate());
      }
      break;
    default:
      if(!TwEventKeyboardGLUT(key,mouse_x,mouse_y))
      {
        cout<<"Unknown key command: "<<key<<" "<<int(key)<<endl;
      }
  }

  glutPostRedisplay();
}


int main(int argc, char * argv[])
{
  using namespace std;
  using namespace Eigen;
  using namespace igl;
  string filename = "../shared/decimated-knight.obj";
  string skel_filename = "";
  output_filename = "";
  switch(argc)
  {
    case 4:
      output_filename = argv[3];
      //fall through
    case 3:
      skel_filename = argv[2];
      if(output_filename.size() == 0)
      {
        output_filename = skel_filename;
      }
      //fall through
    case 2:
      // Read and prepare mesh
      filename = argv[1];
      break;
    default:
      cerr<<"Usage:"<<endl<<"    ./example input.obj [input/output.tgf]"<<endl;
      cout<<endl<<"Opening default mesh..."<<endl;
  }

  // print key commands
  cout<<"[Click] and [drag]     Create bone (or select node) and reposition."<<endl;
  cout<<"⇧ +[Click] and [drag]  Select node (or create one) and _pull out_ new bone."<<endl;
  cout<<"⌥ +[Click] and [drag]  Rotate secene."<<endl;
  cout<<"⌫                      Delete selected node(s) and incident bones."<<endl;
  cout<<"A,a                    Select all."<<endl;
  cout<<"D,d                    Deselect all."<<endl;
  cout<<"C,c                    Snap close nodes."<<endl;
  cout<<"P,p                    Split \"parent\" bone(s) of selection by creating new node(s)."<<endl;
  cout<<"R,r                    Breadth first search at selection to redirect skeleton into tree."<<endl;
  cout<<"S,s                    Save current skeleton to output .tgf file."<<endl;
  cout<<"U,u                    Project then unproject inside mesh (as if dragging each by ε)."<<endl;
  cout<<"Y,Y                    Symmetrize selection over plane through object centroid and right vector."<<endl;
  cout<<"Z,z                    Snap to canonical view."<<endl;
  cout<<"⌘ Z                    Undo."<<endl;
  cout<<"⇧ ⌘ Z                  Redo."<<endl;
  cout<<"^C,ESC                 Exit (without saving)."<<endl;

  string dir,_1,_2,name;
  read_triangle_mesh(filename,V,F,dir,_1,_2,name);

  if(output_filename.size() == 0)
  {
    output_filename = dir+"/"+name+".tgf";
  }

  if(file_exists(output_filename.c_str()))
  {
    cout<<YELLOWGIN("Output set to overwrite "<<output_filename)<<endl;
  }else
  {
    cout<<BLUEGIN("Output set to "<<output_filename)<<endl;
  }

  if(skel_filename.length() > 0)
  {
    readTGF(skel_filename,s.C,s.BE);
  }

  init_relative();
  ei.init(V.cast<float>(),F.cast<int>());

  // Init glut
  glutInit(&argc,argv);
  if( !TwInit(TW_OPENGL, NULL) )
  {
    // A fatal error occured
    fprintf(stderr, "AntTweakBar initialization failed: %s\n", TwGetLastError());
    return 1;
  }
  // Create a tweak bar
  rebar.TwNewBar("TweakBar");
  rebar.TwAddVarRW("camera_rotation", TW_TYPE_QUAT4D,
    camera.m_rotation_conj.coeffs().data(), "open readonly=true");
  TwType RotationTypeTW = ReTwDefineEnumFromString("RotationType",
    "igl_trackball,two-a...-fixed-up");
  rebar.TwAddVarCB( "rotation_type", RotationTypeTW,
    set_rotation_type,get_rotation_type,NULL,"keyIncr=] keyDecr=[");
  rebar.TwAddVarRW("skeleton_on_top", TW_TYPE_BOOLCPP,&skeleton_on_top,"key=O");
  rebar.TwAddVarRW("wireframe", TW_TYPE_BOOLCPP,&wireframe,"key=l");
  TwType SkelStyleTypeTW = ReTwDefineEnumFromString("SkelStyleType",
    "3d,vector-graphics");
  rebar.TwAddVarRW("style",SkelStyleTypeTW,&skel_style,"");
  rebar.TwAddVarRW("alpha",TW_TYPE_DOUBLE,&alpha,
    "keyIncr=} keyDecr={ min=0 max=1 step=0.1");
  rebar.load(REBAR_NAME);

  // Init antweakbar
  glutInitDisplayString( "rgba depth double samples>=8 ");
  glutInitWindowSize(glutGet(GLUT_SCREEN_WIDTH)/2.0,glutGet(GLUT_SCREEN_HEIGHT)/2.0);
  glutCreateWindow("skeleton-builder");
  glutDisplayFunc(display);
  glutReshapeFunc(reshape);
  glutKeyboardFunc(key);
  glutMouseFunc(mouse);
  glutMotionFunc(mouse_drag);
  glutPassiveMotionFunc((GLUTmousemotionfun)TwEventMouseMotionGLUT);
  glutMainLoop();

  return 0;
}