/* Auteur: Nicolas JANEY                    */
/* nicolas.janey@univ-fcomte.fr             */
/* Juillet 2001                             */
/* Occultation entre facettes en radiosite  */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include <GL/glut.h>
#include <GL/gl.h>
#include <GL/glu.h>

#include "ModuleCouleurs.h"
#include "ModuleReshape.h"
#include "ModuleManipulateur.h"
#include "ModuleMenus.h"
#include "ModuleFont.h"
#include "ModuleFleche.h"

struct coord3D {
  float x;
  float y;
  float z; } ;

struct direc3D {
  float x;
  float y;
  float z; } ;

struct facette4 {
  coord3D pt[4] ; } ;

struct facette3 {
  coord3D pt[3] ; } ;

struct rayon {
  coord3D o ;
  direc3D d ; } ; 

static float cote = 4.0F;
static int disc = 10;
static facette4 fi = { {{ -5.0F,-4.0F,-3.0F },
                        { -4.0F,-4.0F,3.5F },
                        { 5.5F,-4.0F,4.5F },
                        { 3.5F,-4.0F,-5.0F }} };
static facette4 fj1 = { {{ -1.0F,-1.0F,-10.0F },
                         { 4.5F,0.5F,-7.5F },
                         { 2.0F,5.0F,-5.0F },
                         { -2.0F,6.5F,-5.0F }} };
static facette4 fj2 = { {{ -1.0F,5.5F,3.0F },
                         { 3.5F,6.5F,2.5F },
                         { 2.0F,4.5F,-4.0F },
                         { -3.0F,3.5F,-3.0F }} };
static facette4 fj3 = { {{ 5.5F,2.5F,4.5F },
                         { 6.0F,2.5F,-5.0F },
                         { -4.0F,2.5F,-6.5F },
                         { -3.0F,2.5F,5.5F }} };
static facette4 *fj = &fj1;

float produitScalaire(direc3D *v1,direc3D *v2) {
  return(v1->x*v2->x+v1->y*v2->y+v1->z*v2->z);
}

void produitVectoriel(direc3D *v1,direc3D *v2,direc3D *v) {
  v->x = v1->y*v2->z-v2->y*v1->z;
  v->y = v1->z*v2->x-v2->z*v1->x;
  v->z = v1->x*v2->y-v2->x*v1->y;
}

void vecteur(coord3D *p1,coord3D *p2,direc3D *v) {
  v->x = p2->x - p1->x;
  v->y = p2->y - p1->y;
  v->z = p2->z - p1->z;
}

void normalize(direc3D *n) {
  double d =sqrt(n->x*n->x+n->y*n->y+n->z*n->z);
  if ( d != 0.0 ) {
    n->x /= d;
    n->y /= d;
    n->z /= d; }
}

void normale(facette4 *f,direc3D *n) {
  direc3D v1;
  direc3D v2;
  vecteur(&f->pt[0],&f->pt[1],&v1);
  vecteur(&f->pt[0],&f->pt[2],&v2);
  produitVectoriel(&v1,&v2,n);
  normalize(n);
}

void centre(facette4 *f,coord3D *p) {
  p->x = (f->pt[0].x+f->pt[1].x+f->pt[2].x+f->pt[3].x)/4.0F;
  p->y = (f->pt[0].y+f->pt[1].y+f->pt[2].y+f->pt[3].y)/4.0F;
  p->z = (f->pt[0].z+f->pt[1].z+f->pt[2].z+f->pt[3].z)/4.0F;
}

void centrePondere(facette4 *f,coord3D *p,float c0,float c1,float c2,float c3) {
  p->x = (f->pt[0].x*c0+f->pt[1].x*c1+f->pt[2].x*c2+f->pt[3].x*c3)/(c0+c1+c2+c3);
  p->y = (f->pt[0].y*c0+f->pt[1].y*c1+f->pt[2].y*c2+f->pt[3].y*c3)/(c0+c1+c2+c3);
  p->z = (f->pt[0].z*c0+f->pt[1].z*c1+f->pt[2].z*c2+f->pt[3].z*c3)/(c0+c1+c2+c3);
}

void vecteursOrthogonaux(direc3D *d,direc3D *d1,direc3D *d2) {
  d1->x = d->y;
  d1->y = -d->x;
  d1->z = 0.0F;
  normalize(d1);
  produitVectoriel(d,d1,d2);
}

void afficheSommet(coord3D *p) {
  glPushMatrix();
  glTranslatef(p->x,p->y,p->z);
  glEnable(GL_LIGHTING);
  glutSolidSphere(0.1,10,10);
  glDisable(GL_LIGHTING);
  glPopMatrix();
}

void myinit(void) {
  glDepthFunc(GL_LESS);
  glEnable(GL_DEPTH_TEST);
  glEnable(GL_AUTO_NORMAL);
  glEnable(GL_NORMALIZE) ;
  glEnable(GL_LIGHT0);
  glEnable(GL_ALPHA_TEST);
  glEnable(GL_BLEND);
  glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
  glClearColor(1.0F,1.0F,0.9F,0.0F);
}

void traceFacette4(int type,facette4 *f) {
  glBegin(type);
  for ( int i = 0 ; i < 4 ; i++ )
    glVertex3f(f->pt[i].x,f->pt[i].y,f->pt[i].z);
  glEnd();
}

void axes() {
  setFont(GLUT_BITMAP_8_BY_13,CENTER);
  glColor4fv(couleurRouge());
  flecheEnVolume(1.0F,0.0F,0.0F,0.1F,0.3F,0.02F);
  glColor4fv(couleurVert());
  flecheEnVolume(0.0F,1.0F,0.0F,0.1F,0.3F,0.02F);
  glColor4fv(couleurBleu());
  flecheEnVolume(0.0F,0.0F,1.0F,0.1F,0.3F,0.02F);
  glPushAttrib(GL_DEPTH_TEST);
  glDisable(GL_DEPTH_TEST);
  glColor4fv(couleurRougeFonce());
  bitmapStringOutput(1.3F,0.0F,0.0F,"x");
  glColor4fv(couleurVertFonce());
  bitmapStringOutput(0.0F,1.3F,0.0F,"y");
  glColor4fv(couleurBleuFonce());
  bitmapStringOutput(0.0F,0.0F,1.3F,"z");
  glPopAttrib();
}

void axeDeProjectionSommets(facette4 *fj,coord3D *c1) {
  glBegin(GL_LINES);
  glVertex3fv((float *) c1);
  glVertex3fv((float *) &fj->pt[0]);
  glVertex3fv((float *) c1);
  glVertex3fv((float *) &fj->pt[1]);
  glVertex3fv((float *) c1);
  glVertex3fv((float *) &fj->pt[2]);
  glVertex3fv((float *) c1);
  glVertex3fv((float *) &fj->pt[3]);
  glEnd(); 
}

int testIntersectionRayonAuDelaFacette(facette3 *f,rayon *r,coord3D *pi) {
  float x1 = f->pt[1].x-f->pt[0].x;
  float y1 = f->pt[1].y-f->pt[0].y;
  float z1 = f->pt[1].z-f->pt[0].z;
  float x2 = f->pt[2].x-f->pt[0].x;
  float y2 = f->pt[2].y-f->pt[0].y;
  float z2 = f->pt[2].z-f->pt[0].z;
  float x3 = r->d.x;
  float y3 = r->d.y;
  float z3 = r->d.z;
  float dx = r->o.x - f->pt[0].x;
  float dy = r->o.y - f->pt[0].y;
  float dz = r->o.z - f->pt[0].z;
  float d = z1*y3*x2-y1*z3*x2-x3*z1*y2-y3*x1*z2+z3*x1*y2+x3*y1*z2;
  if ( d != 0.0F ) {
    float v = -(-x3*y1*dz-z3*x1*dy+y1*z3*dx+x3*z1*dy+y3*x1*dz-z1*y3*dx)/d;
    if ( v >= 0.0F ) {
      float u = (-y3*dx*z2+y3*x2*dz-x2*z3*dy+dx*z3*y2-x3*y2*dz+x3*dy*z2)/d;
      if ( ( u >= 0.0F ) && ( u+v <= 1.0F ) ) {
        float t = -(-dx*z1*y2+dx*y1*z2+x1*y2*dz-x1*dy*z2-x2*y1*dz+x2*z1*dy)/d;
        if ( ( t > 0.0F ) && ( t < 1.0F ) ) {
          pi->x = r->o.x + t*x3;
          pi->y = r->o.y + t*y3;
          pi->z = r->o.z + t*z3;
          return(1); } } } }
  return(0);
}

int testOccultationSommet(coord3D *p,coord3D *c,facette3 *f1,facette3 *f2,coord3D *pi) {
  rayon r;
  r.o = *c;
  r.d.x = p->x-c->x;
  r.d.y = p->y-c->y;
  r.d.z = p->z-c->z;
  if ( testIntersectionRayonAuDelaFacette(f1,&r,pi) ) {
    return(1); }
    else
    if ( testIntersectionRayonAuDelaFacette(f2,&r,pi) ) {
      return(1); }
  return(0);
}

void chercheOccultation2(facette4 *f1,facette4 *f2,coord3D *c,float *cbord,float *cint) {
  facette3 ff1;
  facette3 ff2;
  ff1.pt[0] = f2->pt[0];
  ff1.pt[1] = f2->pt[1];
  ff1.pt[2] = f2->pt[2];
  ff2.pt[0] = f2->pt[0];
  ff2.pt[1] = f2->pt[2];
  ff2.pt[2] = f2->pt[3];
  coord3D pi1,pi2,pi3,pi4;
  int nint = 0;
  if ( testOccultationSommet(&f1->pt[0],c,&ff1,&ff2,&pi1) ) {
    nint++ ;
    afficheSommet(&pi1); }
  if ( testOccultationSommet(&f1->pt[1],c,&ff1,&ff2,&pi2) ) {
    nint++ ;
    afficheSommet(&pi2); }
  if ( testOccultationSommet(&f1->pt[2],c,&ff1,&ff2,&pi3) ) {
    nint++ ;
    afficheSommet(&pi3); }
  if ( testOccultationSommet(&f1->pt[3],c,&ff1,&ff2,&pi4) ) {
    nint++ ;
    afficheSommet(&pi4); }
  if ( nint == 4 ) {
    facette4 fac;
    fac.pt[0] = pi1;
    fac.pt[1] = pi2;
    fac.pt[2] = pi3;
    fac.pt[3] = pi4;
    glColor4fv(cbord);
    traceFacette4(GL_LINE_LOOP,&fac);
    glColor4fv(cint);
    traceFacette4(GL_QUADS,&fac); }
}

void vecteurOrthogonal(coord3D *a,coord3D *b,coord3D *c,direc3D *n) {
  direc3D v1;
  direc3D v2;
  vecteur(a,b,&v1);
  vecteur(a,c,&v2);
  produitVectoriel(&v1,&v2,n);
}

void rechercheOccultationSommetDuBord(coord3D *pa1,coord3D *pa2,coord3D *pb1,coord3D *pb2,coord3D *c,coord3D *pi) {
  direc3D v1;
  direc3D v2;
  vecteurOrthogonal(pa1,pa2,c,&v1);
  vecteurOrthogonal(pb1,pb2,c,&v2);
  direc3D v;
  produitVectoriel(&v1,&v2,&v);
  float alpha = (pb1->y - c->y)/v.y;
  pi->y = pb1->y;
  pi->x = c->x + v.x * alpha;
  pi->z = c->z + v.z * alpha;
}

void chercheOccultation1(facette4 *f1,facette4 *f2,coord3D *c,float *cbord,float *cint) {
  facette3 ff1;
  facette3 ff2;
  ff1.pt[0] = f2->pt[0];
  ff1.pt[1] = f2->pt[1];
  ff1.pt[2] = f2->pt[2];
  ff2.pt[0] = f2->pt[0];
  ff2.pt[1] = f2->pt[2];
  ff2.pt[2] = f2->pt[3];
  coord3D pi1,pi2,pi3,pi4;
  rechercheOccultationSommetDuBord(&f1->pt[0],&f1->pt[3],&f2->pt[1],&f2->pt[2],c,&pi1);
  afficheSommet(&pi1);
  rechercheOccultationSommetDuBord(&f1->pt[1],&f1->pt[2],&f2->pt[1],&f2->pt[2],c,&pi2);
  afficheSommet(&pi2);
  testOccultationSommet(&f1->pt[2],c,&ff1,&ff2,&pi3);
  afficheSommet(&pi3);
  testOccultationSommet(&f1->pt[3],c,&ff1,&ff2,&pi4);
  afficheSommet(&pi4);
  facette4 fac;
  fac.pt[0] = pi1;
  fac.pt[1] = pi2;
  fac.pt[2] = pi3;
  fac.pt[3] = pi4;
  glColor4fv(cbord);
  traceFacette4(GL_LINE_LOOP,&fac);
  glColor4fv(cint);
  traceFacette4(GL_QUADS,&fac);
}

void display(void) {
  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
  direc3D n1;
  coord3D c1;
  normale(&fi,&n1);
  centre(&fi,&c1);
  glPushMatrix();
  glPushMatrix();
  manipulateurSouris();
  manipulateurClavier();
  { glColor4fv(couleurRoseFonce(0.4F));
    direc3D d1;
    direc3D d2;
    vecteursOrthogonaux(&n1,&d1,&d2);
    glBegin(GL_POLYGON);
    glVertex3f(c1.x+d1.x/2+d2.x/2,c1.y+d1.y/2+d2.y/2,c1.z+d1.z/2+d2.z/2);
    glVertex3f(c1.x+d1.x/2-d2.x/2,c1.y+d1.y/2-d2.y/2,c1.z+d1.z/2-d2.z/2);
    glVertex3f(c1.x-d1.x/2-d2.x/2,c1.y-d1.y/2-d2.y/2,c1.z-d1.z/2-d2.z/2);
    glVertex3f(c1.x-d1.x/2+d2.x/2,c1.y-d1.y/2+d2.y/2,c1.z-d1.z/2+d2.z/2);
    glEnd(); }
  glClear(GL_DEPTH_BUFFER_BIT);
  glColor4fv(couleurBleuCiel(0.4F));
  traceFacette4(GL_QUADS,&fj1);
  glColor4fv(couleurJauneClair(0.4F));
  traceFacette4(GL_QUADS,&fj2);
  glColor4fv(couleurRose(0.4F));
  traceFacette4(GL_QUADS,&fj3);
  glClear(GL_DEPTH_BUFFER_BIT);
  { glColor4fv(couleurRougeFonce());
    setAlignement(CENTER);
    coord3D cc;
    centrePondere(&fi,&cc,1.0F,1.0F,2.0F,1.0F);
    placeFontCursor(cc.x,cc.y,cc.z) ;
    simpleBitmapOutput(REGULAR8x13,"dA") ;
    deplacementCursor(11,0,0) ;
    simpleBitmapOutput(REGULAR6x10,"i") ; }
  glColor4fv(couleurBleu());
  traceFacette4(GL_LINE_LOOP,&fj1);
  glColor4fv(couleurJaune());
  traceFacette4(GL_LINE_LOOP,&fj2);
  glColor4fv(couleurRouge());
  traceFacette4(GL_LINE_LOOP,&fj3);
  { glColor4fv(couleurRouge());
    glPushMatrix();
    glTranslatef(c1.x,c1.y,c1.z);
    flecheEnVolume(n1.x*cote,n1.y*cote,n1.z*cote,0.1F,0.3F,0.02F);
    glPopMatrix();
    glColor4fv(couleurRougeFonce());
    setAlignement(LEFT);
    placeFontCursor(c1.x+n1.x*2.5,c1.y+n1.y*2.5,c1.z+n1.z*2.5) ;
    deplacementCursor(5,0,0) ;
    simpleBitmapOutput(REGULAR8x13,"N") ;
    deplacementCursor(15,0,0) ;
    simpleBitmapOutput(REGULAR6x10,"i") ;
    placeFontCursor(c1.x+n1.x*2.5,c1.y+n1.y*2.5,c1.z+n1.z*2.5) ;
    deplacementCursor(4,-5,0) ;
    simpleBitmapOutput(DESSIN,"TF") ; }
  { glColor4fv(couleurBleuFonce());
    setAlignement(CENTER);
    coord3D cc;
    centrePondere(&fj1,&cc,8.0F,1.0F,1.0F,1.0F);
    placeFontCursor(cc.x,cc.y,cc.z) ;
    simpleBitmapOutput(REGULAR8x13,"A") ;
    deplacementCursor(7,0,0) ;
    simpleBitmapOutput(REGULAR6x10,"j") ; }
  { glColor4fv(couleurJauneFonce());
    setAlignement(CENTER);
    coord3D cc;
    centrePondere(&fj2,&cc,8.0F,1.0F,1.0F,1.0F);
    placeFontCursor(cc.x,cc.y,cc.z) ;
    simpleBitmapOutput(REGULAR8x13,"A") ;
    deplacementCursor(7,0,0) ;
    simpleBitmapOutput(REGULAR6x10,"k") ; }
  { glColor4fv(couleurRougeFonce());
    setAlignement(CENTER);
    coord3D cc;
    centrePondere(&fj3,&cc,8.0F,1.0F,1.0F,1.0F);
    placeFontCursor(cc.x,cc.y,cc.z) ;
    simpleBitmapOutput(REGULAR8x13,"A") ;
    deplacementCursor(7,0,0) ;
    simpleBitmapOutput(REGULAR6x10,"l") ; }
  { glColor4fv(couleurRougeFonce());
    direc3D d1;
    direc3D d2;
    vecteursOrthogonaux(&n1,&d1,&d2);
    glBegin(GL_LINE_LOOP);
    glVertex3f(c1.x+d1.x/2+d2.x/2,c1.y+d1.y/2+d2.y/2,c1.z+d1.z/2+d2.z/2);
    glVertex3f(c1.x+d1.x/2-d2.x/2,c1.y+d1.y/2-d2.y/2,c1.z+d1.z/2-d2.z/2);
    glVertex3f(c1.x-d1.x/2-d2.x/2,c1.y-d1.y/2-d2.y/2,c1.z-d1.z/2-d2.z/2);
    glVertex3f(c1.x-d1.x/2+d2.x/2,c1.y-d1.y/2+d2.y/2,c1.z-d1.z/2+d2.z/2);
    glEnd(); }
  { glColor4fv(couleurBleu());
    axeDeProjectionSommets(&fj1,&c1) ;
    glColor4fv(couleurJaune());
    axeDeProjectionSommets(&fj2,&c1) ;
    glColor4fv(couleurRouge());
    axeDeProjectionSommets(&fj3,&c1) ; }
  chercheOccultation1(&fj1,&fj3,&c1,couleurBleu(),couleurBleuCiel(0.4F));
  chercheOccultation2(&fj2,&fj3,&c1,couleurJaune(),couleurJauneClair(0.4F));
  glClear(GL_DEPTH_BUFFER_BIT);
  { glPushMatrix();
    glTranslatef(4.5F,1.0F,5.5F);
    axes();
    glPopMatrix(); }
  glPopMatrix();
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
}

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA|GLUT_DEPTH);
  glutInitWindowPosition(10,10);
  glutInitWindowSize(400,300);
  glutCreateWindow("Occultation entre facettes en radiosite");
  myinit();
  creationMenuBasique();
  setParametresOrthoBasique(-8.0,8.0,-8.0,8.0,-500.0,500.0);
  setManipulateurDistance(1.0F);
  setManipulateurClavierAngle(30.0F,-120.0F,0.0F) ;
  glutReshapeFunc(reshapeOrthoBasique);
  glutKeyboardFunc(keyBasique);
  glutSpecialFunc(specialBasique);
  glutMotionFunc(motionBasique);
  glutMouseFunc(sourisBasique);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}

/* ************************************************** */