/*------------------------------------------------------------------------

  File        : render3d.cpp

  Description : A 3D object software-renderer

  Author      : David Tschumperlé
  
  This software is governed by the CeCILL  license under French law and
  abiding by the rules of distribution of free software.  You can  use, 
  modify and/ or redistribute the software under the terms of the CeCILL
  license as circulated by CEA, CNRS and INRIA at the following URL
  "http://www.cecill.info". 
  
  As a counterpart to the access to the source code and  rights to copy,
  modify and redistribute granted by the license, users are provided only
  with a limited warranty  and the software's author,  the holder of the
  economic rights,  and the successive licensors  have only  limited
  liability. 
  
  In this respect, the user's attention is drawn to the risks associated
  with loading,  using,  modifying and/or developing or reproducing the
  software by the user in light of its specific status of free software,
  that may mean  that it is complicated to manipulate,  and  that  also
  therefore means  that it is reserved for developers  and  experienced
  professionals having in-depth computer knowledge. Users are therefore
  encouraged to load and test the software's suitability as regards their
  requirements in conditions enabling the security of their systems and/or 
  data to be ensured and,  more generally, to use and operate it in the 
  same conditions as regards security. 
  
  The fact that you are presently reading this means that you have had
  knowledge of the CeCILL license and that you accept its terms.
  
  ----------------------------------------------------------------------*/

#include "../CImg.h"
// The lines below are not necessary in your own code, it simply allows 
// the source compilation with compilers that do not respect the C++ standart.
#if ( defined(_MSC_VER) && _MSC_VER<=1200 ) || defined(__DMC__)
#define std
#endif
using namespace cimg_library;

CImgl<> *points_ptr;
int primitive_sorting(const void* A,const void* B);

/*------------------
  Main procedure
  -----------------*/
int main(int argc,char **argv) {
  
  // Read command line arguments
  //----------------------------
  cimg_usage("A real-time 3D object renderer");
  const char *pname = cimg_option("-p",(char*)NULL,"Points datafile");
  const char *fname = cimg_option("-f",(char*)NULL,"Primitives datafile");
  const char *tname = cimg_option("-t",(char*)NULL,"Texture datafile");
  const char *geom  = cimg_option("-g","640x480","Display geometry");
  const bool fullsc = cimg_option("-fullscreen",false,"Fullscreen mode");
  const char *bgcol = cimg_option("-bgcol","100,100,100","Background color");
  const char *lgcol = cimg_option("-lgcol","255,255,255","Light color");
  const char *fccol = cimg_option("-fccol","255,255,255","Faces color");
  const char *lncol = cimg_option("-lncol","255,255,255","Lines color");
  const char *ptcol = cimg_option("-ptcol","255,255,255","Points color");
  const char *bgimg = cimg_option("-bgimg",(char*)NULL,"Background image");
  const char *lgimg = cimg_option("-lgimg",(char*)NULL,"Light image");
  const char *tximg = cimg_option("-tximg",(char*)NULL,"Texture image");
  const unsigned int specul = cimg_option("-specul",50,"Light specularity (when tximg is not defined)");
  unsigned int draw_face    = cimg_option("-df",2,"Draw primitives with faces (0=off,1=flat,2=textured)");
  bool draw_line    = cimg_option("-dl",false,"Draw primitives with lines (on/off)");
  bool draw_corner  = cimg_option("-dc",false,"Draw primitives with corners (on/off)");
  const bool obj_center = cimg_option("-center",true,"Center and scale object");
  const bool add_bbox   = cimg_option("-bbox",false,"Display bounding box");
  const char *params0   = cimg_option("-params","0,0,0,2","Default parameters value (rx,ry,rz,zoom)");
  const char *dparams0  = cimg_option("-dparams","0,0,0,0","Parameters variation (drx,dry,drz,dzoom)");
  const char *file_o    = cimg_option("-o",(char*)NULL,"Output rendered images");
  const char *file_iseq = cimg_option("-iseq",(char*)NULL,"Input motion sequence");
  const char *file_oseq = cimg_option("-oseq",(char*)NULL,"Output motion sequence");
  const unsigned int nb_iter = cimg_option("-iter",-1,"Number of rendering frames");
  const bool helpflag = cimg_option("-h",false,"Display this help");
  if (helpflag) {
    fprintf(stderr,"\nWhen the render window is visible, the following keys can be pressed :\n\n");
    fprintf(stderr,"\tF1 : Swap face rendering (none,flat,textured)\n");
    fprintf(stderr,"\tF2 : Enable/Disable primitives outlines\n");
    fprintf(stderr,"\tF3 : Enable/Disable primitives corners\n");
  }
  
  // Init default parameters colors and images (texture,light,background)
  //---------------------------------------------------------------------
  
  // Parameters and parameters variations
  float alpha=0,beta=0,gamma=0,zoom=1,zoomc=zoom;
  std::sscanf(params0,"%g%*c%g%*c%g%*c%g",&alpha,&beta,&gamma,&zoom);
  alpha*=(float)cimg::PI/180.0f; beta*=(float)cimg::PI/180.0f; gamma*=(float)cimg::PI/180.0f;
  CImg<> params = 
    CImg<>::matrix(1,0,0,0,(float)std::cos(alpha),(float)std::sin(alpha),0,-(float)std::sin(alpha),(float)std::cos(alpha))*
    CImg<>::matrix((float)std::cos(beta),0,-(float)std::sin(beta),0,1,0,(float)std::sin(beta),0,(float)std::cos(beta))*
    CImg<>::matrix((float)std::cos(gamma),-(float)std::sin(gamma),0,(float)std::sin(gamma),(float)std::cos(gamma),0,0,0,1),
    paramsc(params);
  
  float dalpha=0,dbeta=0,dgamma=0,dzoom=0;
  std::sscanf(dparams0,"%g%*c%g%*c%g%*c%g",&dalpha,&dbeta,&dgamma,&dzoom);
  dalpha*=(float)cimg::PI/180.0f; dbeta*=(float)cimg::PI/180.0f; dgamma*=(float)cimg::PI/180.0f;
  CImg<> dparams = 
    CImg<>::matrix(1,0,0,0,(float)std::cos(dalpha),(float)std::sin(dalpha),0,-(float)std::sin(dalpha),(float)std::cos(dalpha))*
    CImg<>::matrix((float)std::cos(dbeta),0,-(float)std::sin(dbeta),0,1,0,(float)std::sin(dbeta),0,(float)std::cos(dbeta))*
    CImg<>::matrix((float)std::cos(dgamma),-(float)std::sin(dgamma),0,(float)std::sin(dgamma),(float)std::cos(dgamma),0,0,0,1);
  
  // Colors and geometry
  unsigned char background_color[3],light_color[3],point_color[3],line_color[3],face_color[3];
  unsigned int r,g,b;
  r=255,g=255,b=255; std::sscanf(bgcol,"%u%*c%u%*c%u",&r,&g,&b); background_color[0]=r; background_color[1]=g; background_color[2]=b;
  r=255,g=255,b=255; std::sscanf(lgcol,"%u%*c%u%*c%u",&r,&g,&b); light_color[0]=r; light_color[1]=g; light_color[2]=b;
  r=255,g=255,b=255; std::sscanf(fccol,"%u%*c%u%*c%u",&r,&g,&b); face_color[0]=r; face_color[1]=g; face_color[2]=b;
  r=255,g=255,b=255; std::sscanf(lncol,"%u%*c%u%*c%u",&r,&g,&b); line_color[0]=r; line_color[1]=g; line_color[2]=b;
  r=255,g=255,b=255; std::sscanf(ptcol,"%u%*c%u%*c%u",&r,&g,&b); point_color[0]=r; point_color[1]=g; point_color[2]=b;
  
  // Background image
  unsigned int width=640,height=480;
  std::sscanf(geom,"%u%*c%u",&width,&height);
  CImg<unsigned char> background = bgimg?CImg<unsigned char>(bgimg):CImg<unsigned char>(width,height,1,3);
  if (!bgimg) {	
    memset(background.ptr(0,0,0,0),background_color[0],background.size()/3);
    memset(background.ptr(0,0,0,1),background_color[1],background.size()/3);
    memset(background.ptr(0,0,0,2),background_color[2],background.size()/3); 
  }
  
  // Light image
  CImg<unsigned char> light = lgimg?CImg<unsigned char>(lgimg):CImg<unsigned char>(256,256,1,3);
  if (!lgimg) light.draw_gaussian(light.dimx()/2.0f,light.dimy()/2.0f,(float)specul,light_color);
  
  // Texture image
  CImg<unsigned char> texture = tximg?CImg<unsigned char>(tximg):CImg<unsigned char>(256,1,1,3);
  if (!tximg) cimg_mapX(texture,x) { texture(x,0,0,0) = x; texture(x,0,0,2) = x/2; texture(x,0,0,1) = x/3; }
  
  // Input-output motion sequences
  CImgl<> iseq, oseq;
  if (file_iseq) iseq = CImgl<>(file_iseq);
  
  // Display window
  CImgDisplay disp(background,pname?cimg::basename(pname):"Demo 3D object",0,3+(fullsc?4:0)+16);
  
  // Init the 3D object
  //-------------------
  CImgl<> points, mappings;
  CImgl<unsigned int> primitives;
  
  if (pname) {
    // load 3d object on the disk
    points = CImgl<>(pname);
    if (fname) primitives = CImgl<unsigned int>(fname);
    else cimgl_map(points,l) primitives.insert(CImg<unsigned int>::vector(l));
    if (tname) mappings = CImgl<>(tname); else mappings = CImgl<>(points.size);
  }
  else {
    cimg::warn(true,"No input 3D object specified. ** Running demo mode. Please try '%s -h' to get rendering options **.",
	       cimg::basename(argv[0]));
    // Create the example 3D object (a torus and a textured cube)
    points.insert(CImg<>::vector(-30,-30,-30));
    points.insert(CImg<>::vector( 30,-30,-30));
    points.insert(CImg<>::vector( 30, 30,-30));
    points.insert(CImg<>::vector(-30, 30,-30));
    points.insert(CImg<>::vector(-30,-30, 30));
    points.insert(CImg<>::vector( 30,-30, 30));
    points.insert(CImg<>::vector( 30, 30, 30));
    points.insert(CImg<>::vector(-30, 30, 30));
    mappings.insert(CImg<>::vector(0,0));
    mappings.insert(CImg<>::vector(1,0));
    mappings.insert(CImg<>::vector(1,1));
    mappings.insert(CImg<>::vector(0,1));
    mappings.insert(CImg<>::vector(0,0));
    mappings.insert(CImg<>::vector(1,0));
    mappings.insert(CImg<>::vector(1,1));
    mappings.insert(CImg<>::vector(0,1));
    primitives.insert(CImg<unsigned int>::vector(0,2,1));
    primitives.insert(CImg<unsigned int>::vector(0,3,2));
    primitives.insert(CImg<unsigned int>::vector(4,5,6));
    primitives.insert(CImg<unsigned int>::vector(4,6,7));
    primitives.insert(CImg<unsigned int>::vector(0,4,7));
    primitives.insert(CImg<unsigned int>::vector(0,7,3));
    primitives.insert(CImg<unsigned int>::vector(1,2,5));
    primitives.insert(CImg<unsigned int>::vector(5,2,6));
    primitives.insert(CImg<unsigned int>::vector(0,1,4));
    primitives.insert(CImg<unsigned int>::vector(4,1,5));
    primitives.insert(CImg<unsigned int>::vector(3,7,2));
    primitives.insert(CImg<unsigned int>::vector(2,7,6));
    const float	a = 80, b = 25;
    const unsigned int na = 24, nb = 12;
    for (unsigned int v=0; v<na; v++)
      for (unsigned int u=0; u<nb; u++) {
	const float 
	  alpha = (float)(u*2*cimg::PI/nb),
	  beta = (float)(v*2*cimg::PI/na),
	  x = (float)((a+b*std::cos(alpha))*std::cos(beta)),
	  y = (float)((a+b*std::cos(alpha))*std::sin(beta)),
	  z = (float)(b*std::sin(alpha));
	points.insert(CImg<>::vector(x,y,z));
	mappings.insert(CImg<>());
      }
    for (unsigned int vv=0; vv<na; vv++)
      for (unsigned int uu=0; uu<nb; uu++) {
	const int nv = (vv+1)%na, nu = (uu+1)%nb;
	primitives.insert(CImg<unsigned int>::vector(8+nb*vv+nu,8+nb*vv+uu,8+nb*nv+uu));
	primitives.insert(CImg<unsigned int>::vector(8+nb*vv+nu,8+nb*nv+uu,8+nb*nv+nu));
      }
    // Create the demo background
    CImg<> background0(background,false);
    cimg_mapXY(background0,x,y) {
      background0(x,y,0) = (float)std::fabs(x*std::cos(16.0*y/background.dimy())+y*std::sin(9.0*x/background.dimx()))/6;
      background0(x,y,1) = (float)std::fabs(x*std::sin(18.0*y/background.dimy())-y*std::cos(11.0*x/background.dimx()))/3;
      background0(x,y,2) = (float)std::fabs(x*std::cos(13.0*y/background.dimy())-y*std::sin(8.0*x/background.dimx()));
    }
    background = background0.normalize(0,255);
    texture = CImg<unsigned char>("/usr/local/share/examples/cimg/img/logo.ppm");
    light = CImg<unsigned char>("/usr/local/share/examples/cimg/img/light3d.ppm");
    draw_face = 2;
    draw_corner = true; point_color[0] = point_color[1] = point_color[2] = 255;
    draw_line = true; line_color[0] = 0; line_color[1] = 100; line_color[2] = 255;
    dparams = CImg<>(3,3).fill(1,0,0,0,(float)std::cos(0.05),(float)std::sin(0.05),0,-(float)std::sin(0.05),(float)std::cos(0.05));
  }
  
  // Center the object and compute the Bounding box
  if (obj_center) {
    CImg<> orig = CImg<>::vector(0);
    { cimgl_map(points,l) orig+=points[l]; orig/=points.size; }
    { cimgl_map(points,l) points[l]-=orig; }
    double rmax = 0;
    cimgl_map(points,l) { const double r = points[l].norm(); if (r>rmax) rmax=r; }
    rmax/=100; { cimgl_map(points,l) points[l]/=rmax; }
  }
  
  if (add_bbox) {
    float 
      xmin=points[0](0),xmax=xmin,
      ymin=points[0](1),ymax=ymin,
      zmin=points[0](2),zmax=zmin;
    cimgl_map(points,l) {
      const CImg<> &pt = points[l];
      if (pt(0)<xmin) xmin=pt(0);
      if (pt(0)>xmax) xmax=pt(0);
      if (pt(1)<ymin) ymin=pt(1);
      if (pt(1)>ymax) ymax=pt(1);
      if (pt(2)<zmin) zmin=pt(2);
      if (pt(2)>zmax) zmax=pt(2);
    }
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+0,points.size+1));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+1,points.size+2));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+2,points.size+3));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+3,points.size+0));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+4,points.size+5));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+5,points.size+6));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+6,points.size+7));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+7,points.size+4));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+0,points.size+4));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+1,points.size+5));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+3,points.size+7));
    primitives.insert(CImg<unsigned int>(1,2).fill(points.size+2,points.size+6));
    points.insert(CImg<>::vector(xmin,ymin,zmin));
    points.insert(CImg<>::vector(xmax,ymin,zmin));
    points.insert(CImg<>::vector(xmax,ymax,zmin));
    points.insert(CImg<>::vector(xmin,ymax,zmin));
    points.insert(CImg<>::vector(xmin,ymin,zmax));
    points.insert(CImg<>::vector(xmax,ymin,zmax));
    points.insert(CImg<>::vector(xmax,ymax,zmax));
    points.insert(CImg<>::vector(xmin,ymax,zmax));
  }
  
  // Compute points normals
  CImgl<> normals(points.size,CImg<>::vector(0,0,0));
  cimgl_map(primitives,l) if (primitives[l].dimy()==3) {
    const unsigned int i0 = primitives[l](0), i1 = primitives[l](1), i2 = primitives[l](2);
    const CImg<> &p0 = points[i0], &p1 = points[i1], &p2 = points[i2];
    CImg<> p0p1(p1), p0p2(p2), p1p2(p2);
    p0p1-=p0;	p0p2-=p0;	p1p2-=p1;
    CImg<> p0p1p(p0p1);
    normals[i0] += p0p1.cross(p0p2);
    normals[i1] += p0p1p.cross(p1p2);
    normals[i2] += p0p2.cross(p1p2);
  }
  { cimgl_map(normals,l) normals[l]/=normals[l].norm()+1e-8;}
  
  // Create transformed mapping coordinates to speed up rendering    
  CImgl<int> imappings;
  { cimgl_map(mappings,l) switch (mappings[l].dimy()) {
    case 1: imappings.insert(CImg<int>(1,2).fill((int)(mappings[l](0)*(texture.dimx()-1)),0)); break;
    case 2: imappings.insert(CImg<int>(1,2).fill((int)(mappings[l](0)*(texture.dimx()-1)),(int)(mappings[l](1)*(texture.dimy()-1)))); break;
    default: imappings.insert(CImg<int>()); break;
    }
  }
  
  fprintf(stderr,"\n> Object initialized : %d vertices, %d primitives\n",points.size,primitives.size);
  
  //-------------------------
  // Start of the main loop
  //-------------------------
  
  CImgl<> rpoints(points), ppoints(points), rnormals(normals);
  bool stopflag = false;
  int mousexc=-1,mouseyc=-1;
  CImg<unsigned char> img,img0(background);
  const unsigned char white[3] = {255,255,255};
  
  for (unsigned int iter=0; iter<nb_iter && !disp.closed && !stopflag; iter++) {
    if (file_o) { fprintf(stderr,"> Rendering frame %d           \r",iter); fflush(stderr); }
    disp.resize();
    img0 = background.get_resize(disp);
    img=img0;
    
    // Handle input-output motion sequences
    //-------------------------------------
    if (file_oseq) {
      img.draw_text(2,2,white,NULL,1,"Sequence frame %d",oseq.size);
      oseq.insert(params);	
    }
    if (iseq.size) { params = iseq[0]; iseq.remove(0); }
    
    // Compute the rotated points/normals and the projected points
    //-------------------------------------------------------------
    const float focale = 500;
    
    cimgl_map(points,l)	{
      const float 
	X  = points[l](0),  Y  = points[l](1),  Z  = points[l](2),
	Xn = normals[l](0), Yn = normals[l](1), Zn = normals[l](2);
      CImg<> &rpt = rpoints[l], &ppt = ppoints[l], &npt = rnormals[l];
      rpt(0) = params(0,0)*X + params(1,0)*Y + params(2,0)*Z;
      rpt(1) = params(0,1)*X + params(1,1)*Y + params(2,1)*Z;
      rpt(2) = params(0,2)*X + params(1,2)*Y + params(2,2)*Z;
      
      npt(0) = params(0,0)*Xn + params(1,0)*Yn + params(2,0)*Zn;
      npt(1) = params(0,1)*Xn + params(1,1)*Yn + params(2,1)*Zn;
      npt(2) = params(0,2)*Xn + params(1,2)*Yn + params(2,2)*Zn;
      
      const float pZ = ppt(2) = rpt(2) + focale;
      ppt(0) = zoom*focale*rpt(0)/pZ+img.dimx()/2;
      ppt(1) = zoom*focale*rpt(1)/pZ+img.dimy()/2;
    }
    
    // Compute and sort visible primitives
    //-------------------------------------
    CImgl<unsigned int> visible_primitives;
    { cimgl_map(primitives,l) {
	switch (primitives[l].dimy()) {
	case 3: // when the primitive is a triangle
	  {
	    const unsigned int i0 = primitives[l](0), i1 = primitives[l](1), i2 = primitives[l](2);
	    const CImg<> &pp0 = ppoints[i0];
	    CImg<> pp1 = ppoints[i1], pp2 = ppoints[i2];			
	    pp1-=pp0;
	    pp2-=pp0;
	    if (pp1[0]*pp2[1]-pp2[0]*pp1[1]<0) visible_primitives.insert(primitives[l]);
	  }
	  break;
	case 2: // when the primitive is a line or a point
	case 1:
	  visible_primitives.insert(primitives[l]);
	  break;
	}
      }}
    points_ptr = &ppoints;
    std::qsort((void*)(visible_primitives.data),visible_primitives.size,sizeof(CImg<unsigned int>),primitive_sorting);
    { cimgl_map(rnormals,l) {
	const CImg<> &npt = rnormals[l];
	npt(0)=(npt(0)+1)*light.dimx()/2;
	npt(1)=(npt(1)+1)*light.dimy()/2;
      }}
    
    // Draw the object on the screen
    //-------------------------------
    
    { cimgl_map(visible_primitives,l) {
	
	//-------------------------
	// rendering with textures
	//-------------------------
	if (draw_face==2) switch(visible_primitives[l].dimy()) {
	case 3: // face
	  {
	    const unsigned int i0 = visible_primitives[l](0), i1 = visible_primitives[l](1), i2 = visible_primitives[l](2);
	    const CImg<>
	      &p0  = ppoints[i0], &p1  = ppoints[i1], &p2  = ppoints[i2],
	      &np0 = rnormals[i0], &np1 = rnormals[i1], &np2 = rnormals[i2];
	    const CImg<int> &m0  = imappings[i0], &m1 = imappings[i1], &m2 = imappings[i2];
	    if (!m0.dimy() || !m1.dimy() || !m2.dimy()) // no mapping (only light)                              
	      img.draw_triangle((int)p0(0),(int)p0(1),(int)p1(0),(int)p1(1),(int)p2(0),(int)p2(1),
				light,(int)np0(0),(int)np0(1),(int)np1(0),(int)np1(1),(int)np2(0),(int)np2(1));
	    else { // texture mapping + light
	      img.
		draw_triangle((int)p0(0),(int)p0(1),(int)p1(0),(int)p1(1),(int)p2(0),(int)p2(1),
			      texture,m0(0),m0(1),m1(0),m1(1),m2(0),m2(1)).
		draw_triangle((int)p0(0),(int)p0(1),(int)p1(0),(int)p1(1),(int)p2(0),(int)p2(1),
			      light,(int)np0(0),(int)np0(1),(int)np1(0),(int)np1(1),(int)np2(0),(int)np2(1),0.5f);
	    }
	  }
	  break;
          
	case 2: // line
	  {
	    const unsigned int i0 = visible_primitives[l](0), i1 = visible_primitives[l](1);
	    const CImg<> &p0 = ppoints[i0], &p1 = ppoints[i1];
	    const CImg<int> &m0 = imappings[i0], &m1 = imappings[i1];
	    if (!m0.dimy() || !m1.dimy()) img.draw_line((int)p0(0),(int)p0(1),(int)p1(0),(int)p1(1),line_color);
	    else img.draw_line((int)p0(0),(int)p0(1),(int)p1(0),(int)p1(1),texture,m0(0),m0(1),m1(0),m1(1));
	  }
	  break;
	  
	case 1: // point
	  {
	    const unsigned int i0 = visible_primitives[l](0);
	    const CImg<> &p0 = ppoints[i0];
	    const CImg<int> &m0 = imappings[i0];
	    const int X = (int)p0(0), Y = (int)p0(1);
	    if (X>=0 && X<(int)img.dimx() && Y>=0 && Y<(int)img.dimy())
	      if (!m0.dimy()) { img(X,Y,0) = point_color[0]; img(X,Y,1) = point_color[1]; img(X,Y,2) = point_color[2]; }
	      else { img(X,Y,0) = texture(m0(0),m0(1),0,0); img(X,Y,1) = texture(m0(0),m0(1),0,1); img(X,Y,2) = texture(m0(0),m0(1),0,2); }
	  }
	  break;    
	}
	
	//-----------------------------
	// rendering with flat shading
	//-----------------------------
	if (draw_face==1) switch(visible_primitives[l].dimy()) {
	case 3: // face
	  {
	    const unsigned int i0 = visible_primitives[l](0), i1 = visible_primitives[l](1), i2 = visible_primitives[l](2);
	    const CImg<>
	      &p0  = ppoints[i0], &p1  = ppoints[i1], &p2  = ppoints[i2],
	      &np0 = rnormals[i0], &np1 = rnormals[i1], &np2 = rnormals[i2];
	    float cz = -(np0(2)+np1(2)+np2(2))/3;                   
	    if (cz<0) cz=0;
	    unsigned char color[3];
	    color[0] = (unsigned char)(face_color[0]*cz);
	    color[1] = (unsigned char)(face_color[1]*cz);
	    color[2] = (unsigned char)(face_color[2]*cz);
	    img.draw_triangle((int)p0(0),(int)p0(1),(int)p1(0),(int)p1(1),(int)p2(0),(int)p2(1),color);
	  }
	  break;
	  
	case 2: // line
	  {
	    const unsigned int i0 = visible_primitives[l](0), i1 = visible_primitives[l](1);
	    const CImg<> &p0 = ppoints[i0], &p1 = ppoints[i1];
	    img.draw_line((int)p0(0),(int)p0(1),(int)p1(0),(int)p1(1),line_color);                    
	  }
	  break;
	  
	case 1: // point
	  {
	    const unsigned int i0 = visible_primitives[l](0);
	    const CImg<> &p0 = ppoints[i0];                    
	    const int X = (int)p0(0), Y = (int)p0(1);
	    if (X>=0 && X<(int)img.dimx() && Y>=0 && Y<(int)img.dimy()) {
	      img(X,Y,0) = point_color[0]; img(X,Y,1) = point_color[1]; img(X,Y,2) = point_color[2]; 
	    }                        
	  }
	  break;    
	}
	
	//-------------------------
	// rendering with outlines
	//-------------------------
	if (draw_line) switch(visible_primitives[l].dimy()) {
	case 3: // face
	  {
	    const unsigned int i0 = visible_primitives[l](0), i1 = visible_primitives[l](1), i2 = visible_primitives[l](2);
	    const CImg<> &p0  = ppoints[i0], &p1  = ppoints[i1], &p2  = ppoints[i2];
	    img.draw_line((int)p0(0),(int)p0(1),(int)p1(0),(int)p1(1),line_color); 
	    img.draw_line((int)p0(0),(int)p0(1),(int)p2(0),(int)p2(1),line_color);
	    img.draw_line((int)p2(0),(int)p2(1),(int)p1(0),(int)p1(1),line_color);
	  }
	  break;
	  
	case 2: // line
	  {
	    const unsigned int i0 = visible_primitives[l](0), i1 = visible_primitives[l](1);
	    const CImg<> &p0 = ppoints[i0], &p1 = ppoints[i1];
	    img.draw_line((int)p0(0),(int)p0(1),(int)p1(0),(int)p1(1),line_color);                    
	  }
	  break;
	  
	case 1: // point
	  {
	    const unsigned int i0 = visible_primitives[l](0);
	    const CImg<> &p0 = ppoints[i0];                    
	    const int X = (int)p0(0), Y = (int)p0(1);
	    if (X>=0 && X<(int)img.dimx() && Y>=0 && Y<(int)img.dimy()) {
	      img(X,Y,0) = point_color[0]; img(X,Y,1) = point_color[1]; img(X,Y,2) = point_color[2]; 
	    }                        
	  }
	  break;    
	}
	
	//------------------------------
	// rendering with corner points
	//------------------------------
	if (draw_corner) switch(visible_primitives[l].dimy()) {
	case 3: // face
	  {
	    const unsigned int i0 = visible_primitives[l](0), i1 = visible_primitives[l](1), i2 = visible_primitives[l](2);
	    const CImg<> &p0  = ppoints[i0], &p1  = ppoints[i1], &p2  = ppoints[i2];
	    int X = (int)p0(0), Y = (int)p0(1);
	    if (X>=0 && X<(int)img.dimx() && Y>=0 && Y<(int)img.dimy()) { img(X,Y,0) = point_color[0]; img(X,Y,1) = point_color[1]; img(X,Y,2) = point_color[2]; }
	    X = (int)p1(0); Y = (int)p1(1);
	    if (X>=0 && X<(int)img.dimx() && Y>=0 && Y<(int)img.dimy()) { img(X,Y,0) = point_color[0]; img(X,Y,1) = point_color[1]; img(X,Y,2) = point_color[2]; }
	    X = (int)p2(0); Y = (int)p2(1);
	    if (X>=0 && X<(int)img.dimx() && Y>=0 && Y<(int)img.dimy()) { img(X,Y,0) = point_color[0]; img(X,Y,1) = point_color[1]; img(X,Y,2) = point_color[2]; }
	  }
	  break;
	  
	case 2: // line
	  {
	    const unsigned int i0 = visible_primitives[l](0), i1 = visible_primitives[l](1);
	    const CImg<> &p0 = ppoints[i0], &p1 = ppoints[i1];
	    int X = (int)p0(0), Y = (int)p0(1);
	    if (X>=0 && X<(int)img.dimx() && Y>=0 && Y<(int)img.dimy()) { img(X,Y,0) = point_color[0]; img(X,Y,1) = point_color[1]; img(X,Y,2) = point_color[2]; }
	    X = (int)p1(0); Y = (int)p1(1);
	    if (X>=0 && X<(int)img.dimx() && Y>=0 && Y<(int)img.dimy()) { img(X,Y,0) = point_color[0]; img(X,Y,1) = point_color[1]; img(X,Y,2) = point_color[2]; }
	  }
	  break;
	  
	case 1: // point
	  {
	    const unsigned int i0 = visible_primitives[l](0);
	    const CImg<> &p0 = ppoints[i0];                    
	    const int X = (int)p0(0), Y = (int)p0(1);
	    if (X>=0 && X<(int)img.dimx() && Y>=0 && Y<(int)img.dimy()) { img(X,Y,0) = point_color[0]; img(X,Y,1) = point_color[1]; img(X,Y,2) = point_color[2]; }
	  }
	  break;    
	}
      }}
    
    // Handle mouse and keys for 3D animation
    //----------------------------------------
    if (disp.key) {
      switch(disp.key) {
      case cimg::keyQ:  stopflag = true; break;
      case cimg::keyF1: draw_face=(draw_face+1)%3; break;
      case cimg::keyF2: draw_line=!draw_line; break;
      case cimg::keyF3: draw_corner=!draw_corner; break;
      }
      disp.key=0;
    }
    
    if (!disp.button) {
      params *= dparams;
      zoom += dzoom;
      if (mousexc>=0 || mouseyc>=0) mousexc=mouseyc=-1;
    }
    else {
      if (mousexc<0 && mouseyc<0) {
	mousexc = disp.mousex;
	mouseyc = disp.mousey;
	paramsc = params;
	zoomc = zoom;
      }
      float u = (float)disp.mousex - mousexc,
	v = (float)disp.mousey - mouseyc,
	n = (float)std::sqrt(u*u+v*v);               
      
      if (disp.button&1 && n>=1) {
	u/=n; v/=n;
	n*=(float)(4*cimg::PI/std::sqrt((double)(disp.dimx()*disp.dimx()+disp.dimy()*disp.dimy())));
	const CImg<> P = CImg<>(3,3).fill(u,-v,0,v,u,0,0,0,1),
	  R = CImg<>(3,3).fill((float)std::cos(n),0,-(float)std::sin(n),0,1,0,(float)std::sin(n),0,(float)std::cos(n));
	params = P*R*P.get_transpose()*paramsc;
      }
      if (disp.button&2) zoom = zoomc+v*5/disp.dimy();
    }
    
    // End of the main loop
    disp.display(img).wait(20);
    if (file_o) img.save(file_o,iter);
    
  }
  
  if (file_oseq) { fprintf(stderr,"> Saving motion sequence '%s'\n",file_oseq); oseq.save(file_oseq); }
  return 0;
}

// function that compares the z between two primitives
//-----------------------------------------------------
int primitive_sorting(const void* A,const void* B) {
  const CImg<unsigned int>& a = *((CImg<unsigned int>*)A), b = *((CImg<unsigned int>*)B);
  const CImgl<>& points = *points_ptr;
  const float
    za = a.dimy()==3?(points[a(0)](2)+points[a(1)](2)+points[a(2)](2))/3:(a.dimy()==2?(points[a(0)](2)+points[a(1)](2))/2:(a.dimy()==1?points[a(0)](2):0)),
    zb = b.dimy()==3?(points[b(0)](2)+points[b(1)](2)+points[b(2)](2))/3:(b.dimy()==2?(points[b(0)](2)+points[b(1)](2))/2:(b.dimy()==1?points[b(0)](2):0));
  if (zb>za) return 1;
  return -1;
}
