vendor/libigl/tutorial/404_DualQuaternionSkinning/main.cpp

#include <igl/directed_edge_orientations.h>
#include <igl/directed_edge_parents.h>
#include <igl/forward_kinematics.h>
#include <igl/PI.h>
#include <igl/lbs_matrix.h>
#include <igl/deform_skeleton.h>
#include <igl/dqs.h>
#include <igl/readDMAT.h>
#include <igl/readOBJ.h>
#include <igl/readTGF.h>
#include <igl/opengl/glfw/Viewer.h>

#include <Eigen/Geometry>
#include <Eigen/StdVector>
#include <vector>
#include <algorithm>
#include <iostream>


typedef 
  std::vector<Eigen::Quaterniond,Eigen::aligned_allocator<Eigen::Quaterniond> >
  RotationList;

const Eigen::RowVector3d sea_green(70./255.,252./255.,167./255.);
Eigen::MatrixXd V,W,C,U,M;
Eigen::MatrixXi F,BE;
Eigen::VectorXi P;
std::vector<RotationList > poses;
double anim_t = 0.0;
double anim_t_dir = 0.015;
bool use_dqs = false;
bool recompute = true;

bool pre_draw(igl::opengl::glfw::Viewer & viewer)
{
  using namespace Eigen;
  using namespace std;
  if(recompute)
  {
    // Find pose interval
    const int begin = (int)floor(anim_t)%poses.size();
    const int end = (int)(floor(anim_t)+1)%poses.size();
    const double t = anim_t - floor(anim_t);

    // Interpolate pose and identity
    RotationList anim_pose(poses[begin].size());
    for(int e = 0;e<poses[begin].size();e++)
    {
      anim_pose[e] = poses[begin][e].slerp(t,poses[end][e]);
    }
    // Propagate relative rotations via FK to retrieve absolute transformations
    RotationList vQ;
    vector<Vector3d> vT;
    igl::forward_kinematics(C,BE,P,anim_pose,vQ,vT);
    const int dim = C.cols();
    MatrixXd T(BE.rows()*(dim+1),dim);
    for(int e = 0;e<BE.rows();e++)
    {
      Affine3d a = Affine3d::Identity();
      a.translate(vT[e]);
      a.rotate(vQ[e]);
      T.block(e*(dim+1),0,dim+1,dim) =
        a.matrix().transpose().block(0,0,dim+1,dim);
    }
    // Compute deformation via LBS as matrix multiplication
    if(use_dqs)
    {
      igl::dqs(V,W,vQ,vT,U);
    }else
    {
      U = M*T;
    }

    // Also deform skeleton edges
    MatrixXd CT;
    MatrixXi BET;
    igl::deform_skeleton(C,BE,T,CT,BET);
    
    viewer.data().set_vertices(U);
    viewer.data().set_edges(CT,BET,sea_green);
    viewer.data().compute_normals();
    if(viewer.core().is_animating)
    {
      anim_t += anim_t_dir;
    }
    else
    {
      recompute=false;
    }
  }
  return false;
}

bool key_down(igl::opengl::glfw::Viewer &viewer, unsigned char key, int mods)
{
  recompute = true;
  switch(key)
  {
    case 'D':
    case 'd':
      use_dqs = !use_dqs;
      return true;
    case ' ':
      viewer.core().is_animating = !viewer.core().is_animating;
      return true;
  }
  return false;
}

int main(int argc, char *argv[])
{
  using namespace Eigen;
  using namespace std;
  igl::readOBJ(TUTORIAL_SHARED_PATH "/arm.obj",V,F);
  U=V;
  igl::readTGF(TUTORIAL_SHARED_PATH "/arm.tgf",C,BE);
  // retrieve parents for forward kinematics
  igl::directed_edge_parents(BE,P);
  RotationList rest_pose;
  igl::directed_edge_orientations(C,BE,rest_pose);
  poses.resize(4,RotationList(4,Quaterniond::Identity()));
  // poses[1] // twist
  const Quaterniond twist(AngleAxisd(igl::PI,Vector3d(1,0,0)));
  poses[1][2] = rest_pose[2]*twist*rest_pose[2].conjugate();
  const Quaterniond bend(AngleAxisd(-igl::PI*0.7,Vector3d(0,0,1)));
  poses[3][2] = rest_pose[2]*bend*rest_pose[2].conjugate();

  igl::readDMAT(TUTORIAL_SHARED_PATH "/arm-weights.dmat",W);
  igl::lbs_matrix(V,W,M);

  // Plot the mesh with pseudocolors
  igl::opengl::glfw::Viewer viewer;
  viewer.data().set_mesh(U, F);
  viewer.data().set_edges(C,BE,sea_green);
  viewer.data().show_lines = false;
  viewer.data().show_overlay_depth = false;
  viewer.data().line_width = 1;
  viewer.core().trackball_angle.normalize();
  viewer.callback_pre_draw = &pre_draw;
  viewer.callback_key_down = &key_down;
  viewer.core().is_animating = false;
  viewer.core().camera_zoom = 2.5;
  viewer.core().animation_max_fps = 30.;
  cout<<"Press [d] to toggle between LBS and DQS"<<endl<<
    "Press [space] to toggle animation"<<endl;
  viewer.launch();
}