template<typename tp, typename tf, typename tc, typename to>
    const CImg<T>& _display_object3d(CImgDisplay& disp, const char *const title,
				     const CImg<tp>& vertices,
				     const CImgList<tf>& primitives,
				     const CImgList<tc>& colors,
                                     const to& opacities,
				     const bool centering,
				     const int render_static, const int render_motion,
				     const bool is_double_sided, const float focale,
                                     const float light_x, const float light_y, const float light_z,
				     const float specular_lightness, const float specular_shininess,
				     const bool display_axes, float *const pose_matrix,
                                     const bool exit_on_anykey) const {
      typedef typename cimg::superset<tp,float>::type tpfloat;

      // Check input arguments
      if (is_empty()) {
	if (disp) return CImg<T>(disp.width(),disp.height(),1,(colors && colors[0].size()==1)?1:3,0).
		    _display_object3d(disp,title,vertices,primitives,colors,opacities,centering,
                                      render_static,render_motion,is_double_sided,focale,
                                      light_x,light_y,light_z,specular_lightness,specular_shininess,
                                      display_axes,pose_matrix,exit_on_anykey);
	else return CImg<T>(1,2,1,1,64,128).resize(cimg_fitscreen(CImgDisplay::screen_width()/2,
                                                                  CImgDisplay::screen_height()/2,1),
                                                   1,(colors && colors[0].size()==1)?1:3,3).
               _display_object3d(disp,title,vertices,primitives,colors,opacities,centering,
				 render_static,render_motion,is_double_sided,focale,
                                 light_x,light_y,light_z,specular_lightness,specular_shininess,
				 display_axes,pose_matrix,exit_on_anykey);
      } else { if (disp) disp.resize(*this,false); }
      CImg<charT> error_message(1024);
      if (!vertices.is_object3d(primitives,colors,opacities,true,error_message))
        throw CImgArgumentException(_cimg_instance
                                    "display_object3d(): Invalid specified 3D object (%u,%u) (%s).",
                                    cimg_instance,vertices._width,primitives._width,error_message.data());
      if (vertices._width && !primitives) {
        CImgList<tf> nprimitives(vertices._width,1,1,1,1);
        cimglist_for(nprimitives,l) nprimitives(l,0) = (tf)l;
        return _display_object3d(disp,title,vertices,nprimitives,colors,opacities,centering,
				 render_static,render_motion,is_double_sided,focale,
                                 light_x,light_y,light_z,specular_lightness,specular_shininess,
				 display_axes,pose_matrix,exit_on_anykey);
      }
      if (!disp) {
	disp.assign(cimg_fitscreen(_width,_height,_depth),title?title:0,3);
        if (!title) disp.set_title("CImg<%s> (%u vertices, %u primitives)",
                                   pixel_type(),vertices._width,primitives._width);
      } else if (title) disp.set_title("%s",title);

      // Init 3D objects and compute object statistics
      CImg<floatT>
        pose,
        rotated_vertices(vertices._width,3),
        bbox_vertices, rotated_bbox_vertices,
        axes_vertices, rotated_axes_vertices,
        bbox_opacities, axes_opacities;
      CImgList<uintT> bbox_primitives, axes_primitives;
      CImgList<tf> reverse_primitives;
      CImgList<T> bbox_colors, bbox_colors2, axes_colors;
      unsigned int ns_width = 0, ns_height = 0;
      int _is_double_sided = (int)is_double_sided;
      bool ndisplay_axes = display_axes;
      const CImg<T>
        background_color(1,1,1,_spectrum,0),
        foreground_color(1,1,1,_spectrum,(T)std::min((int)cimg::type<T>::max(),255));
      float
        Xoff = 0, Yoff = 0, Zoff = 0, sprite_scale = 1,
        xm = 0, xM = vertices?vertices.get_shared_row(0).max_min(xm):0,
        ym = 0, yM = vertices?vertices.get_shared_row(1).max_min(ym):0,
        zm = 0, zM = vertices?vertices.get_shared_row(2).max_min(zm):0;
      const float delta = cimg::max(xM - xm,yM - ym,zM - zm);

      rotated_bbox_vertices = bbox_vertices.assign(8,3,1,1,
                                                   xm,xM,xM,xm,xm,xM,xM,xm,
                                                   ym,ym,yM,yM,ym,ym,yM,yM,
                                                   zm,zm,zm,zm,zM,zM,zM,zM);
      bbox_primitives.assign(6,1,4,1,1, 0,3,2,1, 4,5,6,7, 1,2,6,5, 0,4,7,3, 0,1,5,4, 2,3,7,6);
      bbox_colors.assign(6,_spectrum,1,1,1,background_color[0]);
      bbox_colors2.assign(6,_spectrum,1,1,1,foreground_color[0]);
      bbox_opacities.assign(bbox_colors._width,1,1,1,0.3f);

      rotated_axes_vertices = axes_vertices.assign(7,3,1,1,
                                                   0,20,0,0,22,-6,-6,
                                                   0,0,20,0,-6,22,-6,
                                                   0,0,0,20,0,0,22);
      axes_opacities.assign(3,1,1,1,1);
      axes_colors.assign(3,_spectrum,1,1,1,foreground_color[0]);
      axes_primitives.assign(3,1,2,1,1, 0,1, 0,2, 0,3);

      // Begin user interaction loop
      CImg<T> visu0(*this,false), visu;
      CImg<tpfloat> zbuffer(visu0.width(),visu0.height(),1,1,0);
      bool init_pose = true, clicked = false, redraw = true;
      unsigned int key = 0;
      int
        x0 = 0, y0 = 0, x1 = 0, y1 = 0,
        nrender_static = render_static,
        nrender_motion = render_motion;
      disp.show().flush();

      while (!disp.is_closed() && !key) {

        // Init object pose
        if (init_pose) {
          const float
            ratio = delta>0?(2.f*std::min(disp.width(),disp.height())/(3.f*delta)):1,
            dx = (xM + xm)/2, dy = (yM + ym)/2, dz = (zM + zm)/2;
          if (centering)
            CImg<floatT>(4,3,1,1, ratio,0.,0.,-ratio*dx, 0.,ratio,0.,-ratio*dy, 0.,0.,ratio,-ratio*dz).move_to(pose);
          else CImg<floatT>(4,3,1,1, 1,0,0,0, 0,1,0,0, 0,0,1,0).move_to(pose);
          if (pose_matrix) {
            CImg<floatT> pose0(pose_matrix,4,3,1,1,false);
            pose0.resize(4,4,1,1,0); pose.resize(4,4,1,1,0);
            pose0(3,3) = pose(3,3) = 1;
            (pose0*pose).get_crop(0,0,3,2).move_to(pose);
            Xoff = pose_matrix[12]; Yoff = pose_matrix[13]; Zoff = pose_matrix[14]; sprite_scale = pose_matrix[15];
          } else { Xoff = Yoff = Zoff = 0; sprite_scale = 1; }
          init_pose = false;
          redraw = true;
        }

        // Rotate and draw 3D object
        if (redraw) {
          const float
            r00 = pose(0,0), r10 = pose(1,0), r20 = pose(2,0), r30 = pose(3,0),
            r01 = pose(0,1), r11 = pose(1,1), r21 = pose(2,1), r31 = pose(3,1),
            r02 = pose(0,2), r12 = pose(1,2), r22 = pose(2,2), r32 = pose(3,2);
          if ((clicked && nrender_motion>=0) || (!clicked && nrender_static>=0))
            cimg_forX(vertices,l) {
              const float x = (float)vertices(l,0), y = (float)vertices(l,1), z = (float)vertices(l,2);
              rotated_vertices(l,0) = r00*x + r10*y + r20*z + r30;
              rotated_vertices(l,1) = r01*x + r11*y + r21*z + r31;
              rotated_vertices(l,2) = r02*x + r12*y + r22*z + r32;
            }
          else cimg_forX(bbox_vertices,l) {
              const float x = bbox_vertices(l,0), y = bbox_vertices(l,1), z = bbox_vertices(l,2);
              rotated_bbox_vertices(l,0) = r00*x + r10*y + r20*z + r30;
              rotated_bbox_vertices(l,1) = r01*x + r11*y + r21*z + r31;
              rotated_bbox_vertices(l,2) = r02*x + r12*y + r22*z + r32;
            }

          // Draw objects
          const bool render_with_zbuffer = !clicked && nrender_static>0;
          visu = visu0;
          if ((clicked && nrender_motion<0) || (!clicked && nrender_static<0))
            visu.draw_object3d(Xoff + visu._width/2.f,Yoff + visu._height/2.f,Zoff,
                               rotated_bbox_vertices,bbox_primitives,bbox_colors,bbox_opacities,2,false,focale).
              draw_object3d(Xoff + visu._width/2.f,Yoff + visu._height/2.f,Zoff,
                            rotated_bbox_vertices,bbox_primitives,bbox_colors2,1,false,focale);
          else visu._draw_object3d((void*)0,render_with_zbuffer?zbuffer.fill(0):CImg<tpfloat>::empty(),
                                   Xoff + visu._width/2.f,Yoff + visu._height/2.f,Zoff,
                                   rotated_vertices,reverse_primitives?reverse_primitives:primitives,
                                   colors,opacities,clicked?nrender_motion:nrender_static,_is_double_sided==1,focale,
                                   width()/2.f + light_x,height()/2.f + light_y,light_z + Zoff,
                                   specular_lightness,specular_shininess,1,sprite_scale);
          // Draw axes
          if (ndisplay_axes) {
            const float
              n = 1e-8f + cimg::hypot(r00,r01,r02),
              _r00 = r00/n, _r10 = r10/n, _r20 = r20/n,
              _r01 = r01/n, _r11 = r11/n, _r21 = r21/n,
              _r02 = r01/n, _r12 = r12/n, _r22 = r22/n,
              Xaxes = 25, Yaxes = visu._height - 38.f;
            cimg_forX(axes_vertices,l) {
              const float
                x = axes_vertices(l,0),
                y = axes_vertices(l,1),
                z = axes_vertices(l,2);
              rotated_axes_vertices(l,0) = _r00*x + _r10*y + _r20*z;
              rotated_axes_vertices(l,1) = _r01*x + _r11*y + _r21*z;
              rotated_axes_vertices(l,2) = _r02*x + _r12*y + _r22*z;
            }
            axes_opacities(0,0) = (rotated_axes_vertices(1,2)>0)?0.5f:1.f;
            axes_opacities(1,0) = (rotated_axes_vertices(2,2)>0)?0.5f:1.f;
            axes_opacities(2,0) = (rotated_axes_vertices(3,2)>0)?0.5f:1.f;
            visu.draw_object3d(Xaxes,Yaxes,0,rotated_axes_vertices,axes_primitives,
                               axes_colors,axes_opacities,1,false,focale).
              draw_text((int)(Xaxes + rotated_axes_vertices(4,0)),
                        (int)(Yaxes + rotated_axes_vertices(4,1)),
                        "X",axes_colors[0]._data,0,axes_opacities(0,0),13).
              draw_text((int)(Xaxes + rotated_axes_vertices(5,0)),
                        (int)(Yaxes + rotated_axes_vertices(5,1)),
                        "Y",axes_colors[1]._data,0,axes_opacities(1,0),13).
              draw_text((int)(Xaxes + rotated_axes_vertices(6,0)),
                        (int)(Yaxes + rotated_axes_vertices(6,1)),
                        "Z",axes_colors[2]._data,0,axes_opacities(2,0),13);
          }
          visu.display(disp);
          if (!clicked || nrender_motion==nrender_static) redraw = false;
        }

        // Handle user interaction
        disp.wait();
        if ((disp.button() || disp.wheel()) && disp.mouse_x()>=0 && disp.mouse_y()>=0) {
          redraw = true;
          if (!clicked) { x0 = x1 = disp.mouse_x(); y0 = y1 = disp.mouse_y(); if (!disp.wheel()) clicked = true; }
          else { x1 = disp.mouse_x(); y1 = disp.mouse_y(); }
          if (disp.button()&1) {
            const float
              R = 0.45f*std::min(disp.width(),disp.height()),
              R2 = R*R,
              u0 = (float)(x0 - disp.width()/2),
              v0 = (float)(y0 - disp.height()/2),
              u1 = (float)(x1 - disp.width()/2),
              v1 = (float)(y1 - disp.height()/2),
              n0 = cimg::hypot(u0,v0),
              n1 = cimg::hypot(u1,v1),
              nu0 = n0>R?(u0*R/n0):u0,
              nv0 = n0>R?(v0*R/n0):v0,
              nw0 = (float)std::sqrt(std::max(0.f,R2 - nu0*nu0 - nv0*nv0)),
              nu1 = n1>R?(u1*R/n1):u1,
              nv1 = n1>R?(v1*R/n1):v1,
              nw1 = (float)std::sqrt(std::max(0.f,R2 - nu1*nu1 - nv1*nv1)),
              u = nv0*nw1 - nw0*nv1,
              v = nw0*nu1 - nu0*nw1,
              w = nv0*nu1 - nu0*nv1,
              n = cimg::hypot(u,v,w),
              alpha = (float)std::asin(n/R2)*180/cimg::PI;
            (CImg<floatT>::rotation_matrix(u,v,w,-alpha)*pose).move_to(pose);
            x0 = x1; y0 = y1;
          }
          if (disp.button()&2) {
            if (focale>0) Zoff-=(y0 - y1)*focale/400;
            else { const float s = std::exp((y0 - y1)/400.f); pose*=s; sprite_scale*=s; }
            x0 = x1; y0 = y1;
          }
          if (disp.wheel()) {
            if (focale>0) Zoff-=disp.wheel()*focale/20;
            else { const float s = std::exp(disp.wheel()/20.f); pose*=s; sprite_scale*=s; }
            disp.set_wheel();
          }
          if (disp.button()&4) { Xoff+=(x1 - x0); Yoff+=(y1 - y0); x0 = x1; y0 = y1; }
          if ((disp.button()&1) && (disp.button()&2)) {
            init_pose = true; disp.set_button(); x0 = x1; y0 = y1;
            pose = CImg<floatT>(4,3,1,1, 1,0,0,0, 0,1,0,0, 0,0,1,0);
          }
        } else if (clicked) { x0 = x1; y0 = y1; clicked = false; redraw = true; }

        CImg<charT> filename(32);
        switch (key = disp.key()) {
#if cimg_OS!=2
        case cimg::keyCTRLRIGHT :
#endif
        case 0 : case cimg::keyCTRLLEFT : key = 0; break;
        case cimg::keyD: if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).
              resize(CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,false),
                     CImgDisplay::_fitscreen(3*disp.width()/2,3*disp.height()/2,1,128,-100,true),false).
              _is_resized = true;
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyC : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).
              resize(cimg_fitscreen(2*disp.width()/3,2*disp.height()/3,1),false)._is_resized = true;
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyR : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            disp.set_fullscreen(false).resize(cimg_fitscreen(_width,_height,_depth),false)._is_resized = true;
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyF : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            if (!ns_width || !ns_height ||
                ns_width>(unsigned int)disp.screen_width() || ns_height>(unsigned int)disp.screen_height()) {
              ns_width = disp.screen_width()*3U/4;
              ns_height = disp.screen_height()*3U/4;
            }
            if (disp.is_fullscreen()) disp.resize(ns_width,ns_height,false);
            else {
              ns_width = disp._width; ns_height = disp._height;
              disp.resize(disp.screen_width(),disp.screen_height(),false);
            }
            disp.toggle_fullscreen()._is_resized = true;
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyT : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            // Switch single/double-sided primitives.
            if (--_is_double_sided==-2) _is_double_sided = 1;
            if (_is_double_sided>=0) reverse_primitives.assign();
            else primitives.get_reverse_object3d().move_to(reverse_primitives);
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyZ : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Enable/disable Z-buffer
            if (zbuffer) zbuffer.assign();
            else zbuffer.assign(visu0.width(),visu0.height(),1,1,0);
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyX : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Show/hide 3D axes
            ndisplay_axes = !ndisplay_axes;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF1 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Set rendering mode to points
            nrender_motion = (nrender_static==0 && nrender_motion!=0)?0:-1; nrender_static = 0;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF2 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Set rendering mode to lines
            nrender_motion = (nrender_static==1 && nrender_motion!=1)?1:-1; nrender_static = 1;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF3 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Set rendering mode to flat
            nrender_motion = (nrender_static==2 && nrender_motion!=2)?2:-1; nrender_static = 2;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF4 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Set rendering mode to flat-shaded
            nrender_motion = (nrender_static==3 && nrender_motion!=3)?3:-1; nrender_static = 3;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF5 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) {
            // Set rendering mode to gouraud-shaded.
            nrender_motion = (nrender_static==4 && nrender_motion!=4)?4:-1; nrender_static = 4;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyF6 : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Set rendering mode to phong-shaded
            nrender_motion = (nrender_static==5 && nrender_motion!=5)?5:-1; nrender_static = 5;
            disp.set_key(key,false); key = 0; redraw = true;
          } break;
        case cimg::keyS : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Save snapshot
            static unsigned int snap_number = 0;
            std::FILE *file;
            do {
              cimg_snprintf(filename,filename._width,cimg_appname "_%.4u.bmp",snap_number++);
              if ((file=cimg::std_fopen(filename,"r"))!=0) cimg::fclose(file);
            } while (file);
            (+visu).__draw_text(" Saving snapshot... ",0).display(disp);
            visu.save(filename);
            (+visu).__draw_text(" Snapshot '%s' saved. ",0,filename._data).display(disp);
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyG : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Save object as a .off file
            static unsigned int snap_number = 0;
            std::FILE *file;
            do {
              cimg_snprintf(filename,filename._width,cimg_appname "_%.4u.off",snap_number++);
              if ((file=cimg::std_fopen(filename,"r"))!=0) cimg::fclose(file);
            } while (file);
            (+visu).__draw_text(" Saving object... ",0).display(disp);
            vertices.save_off(reverse_primitives?reverse_primitives:primitives,colors,filename);
            (+visu).__draw_text(" Object '%s' saved. ",0,filename._data).display(disp);
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyO : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Save object as a .cimg file
            static unsigned int snap_number = 0;
            std::FILE *file;
            do {

#ifdef cimg_use_zlib
              cimg_snprintf(filename,filename._width,cimg_appname "_%.4u.cimgz",snap_number++);
#else
              cimg_snprintf(filename,filename._width,cimg_appname "_%.4u.cimg",snap_number++);
#endif
              if ((file=cimg::std_fopen(filename,"r"))!=0) cimg::fclose(file);
            } while (file);
            (+visu).__draw_text(" Saving object... ",0).display(disp);
            vertices.get_object3dtoCImg3d(reverse_primitives?reverse_primitives:primitives,colors,opacities).
              save(filename);
            (+visu).__draw_text(" Object '%s' saved. ",0,filename._data).display(disp);
            disp.set_key(key,false); key = 0;
          } break;

#ifdef cimg_use_board
        case cimg::keyP : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Save object as a .EPS file
            static unsigned int snap_number = 0;
            std::FILE *file;
            do {
              cimg_snprintf(filename,filename._width,cimg_appname "_%.4u.eps",snap_number++);
              if ((file=cimg::std_fopen(filename,"r"))!=0) cimg::fclose(file);
            } while (file);
            (+visu).__draw_text(" Saving EPS snapshot... ",0).display(disp);
            LibBoard::Board board;
            (+visu)._draw_object3d(&board,zbuffer.fill(0),
                                   Xoff + visu._width/2.f,Yoff + visu._height/2.f,Zoff,
                                   rotated_vertices,reverse_primitives?reverse_primitives:primitives,
                                   colors,opacities,clicked?nrender_motion:nrender_static,
                                   _is_double_sided==1,focale,
                                   visu.width()/2.f + light_x,visu.height()/2.f + light_y,light_z + Zoff,
                                   specular_lightness,specular_shininess,1,
                                   sprite_scale);
            board.saveEPS(filename);
            (+visu).__draw_text(" Object '%s' saved. ",0,filename._data).display(disp);
            disp.set_key(key,false); key = 0;
          } break;
        case cimg::keyV : if (disp.is_keyCTRLLEFT() || disp.is_keyCTRLRIGHT()) { // Save object as a .SVG file
            static unsigned int snap_number = 0;
            std::FILE *file;
            do {
              cimg_snprintf(filename,filename._width,cimg_appname "_%.4u.svg",snap_number++);
              if ((file=cimg::std_fopen(filename,"r"))!=0) cimg::fclose(file);
            } while (file);
            (+visu).__draw_text(" Saving SVG snapshot... ",0,13).display(disp);
            LibBoard::Board board;
            (+visu)._draw_object3d(&board,zbuffer.fill(0),
                                   Xoff + visu._width/2.f,Yoff + visu._height/2.f,Zoff,
                                   rotated_vertices,reverse_primitives?reverse_primitives:primitives,
                                   colors,opacities,clicked?nrender_motion:nrender_static,
                                   _is_double_sided==1,focale,
                                   visu.width()/2.f + light_x,visu.height()/2.f + light_y,light_z + Zoff,
                                   specular_lightness,specular_shininess,1,
                                   sprite_scale);
            board.saveSVG(filename);
            (+visu).__draw_text(" Object '%s' saved. ",0,filename._data).display(disp);
            disp.set_key(key,false); key = 0;
          } break;
#endif
        }
        if (disp.is_resized()) {
          disp.resize(false); visu0 = get_resize(disp,1);
          if (zbuffer) zbuffer.assign(disp.width(),disp.height());
          redraw = true;
        }
        if (!exit_on_anykey && key && key!=cimg::keyESC &&
            (key!=cimg::keyW || (!disp.is_keyCTRLLEFT() && !disp.is_keyCTRLRIGHT()))) {
          key = 0;
        }
      }
      if (pose_matrix) {
        std::memcpy(pose_matrix,pose._data,12*sizeof(float));
        pose_matrix[12] = Xoff; pose_matrix[13] = Yoff; pose_matrix[14] = Zoff; pose_matrix[15] = sprite_scale;
      }
      disp.set_button().set_key(key);
      return *this;