/* Auteur: Nicolas JANEY         */ 
/* nicolas.janey@univ-fcomte.fr  */
/* Fevrier 2019                  */
/* Une courbe de Bezier          */

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

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

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

struct coord_3D {
  GLfloat x = 0.0F;
  GLfloat y = 0.0F;
  GLfloat z = 0.0F;
  GLfloat w = 1.0F; };

struct polygone {
  int n = 0;
  coord_3D *p = NULL; };

typedef struct coord_3D coord_3D;
typedef struct polygone polygone;

static GLfloat pts[6][4] = { 
  { -3.0F,-3.0F,-3.0F, 1.0F },
  { -2.0F, 3.0F, 1.0F, 1.0F }, 
  {  2.0F,-3.0F,-2.0F, 1.0F },
  {  3.0F, 3.0F,-3.0F, 1.0F }, 
  { -2.0F,-1.0F, 2.0F, 1.0F },
  {  3.0F,-3.0F,-1.0F, 1.0F } };

static int aff = 2;
static polygone pl;

void point(float x,float y,float z) {
    glVertex3f(x,y,z);
  }

void bezier(polygone *p,int n) {
  int i,j;
  float t,mt;
  float *cn,x,y,z,fac;
  cn =(float *) calloc(p->n,sizeof(float));
  cn[0] = 1;
  cn[1] =(float) (p->n-1);
  for ( i = 2 ; i < p->n ; i++ )
    cn[i] = cn[i-1] * (p->n - i) / i;
  for ( i = 0 ; i < n ; i++ ) {
    t =(float) i/(n-1);
    mt = 1-t;
    x = y = z = 0.0F;
    for ( j = 0 ; j < p->n ; j++ ) {
      fac = cn[j]*(float) pow(t,j)*
                  (float) pow(mt,p->n-1-j);
      x += fac * p->p[j].x;
      y += fac * p->p[j].y;
      z += fac * p->p[j].z; }
    point(x,y,z); }
  free(cn);
}

void display(void) { 
  int i;
  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
  glPushMatrix();
  glEnable(GL_DEPTH_TEST);
  manipulateurSouris();
  manipulateurClavier();
  glColor4fv(couleurCyan());
  glBegin(GL_LINE_STRIP);
  for ( i = 0 ; i <= 30 ; i++ ) 
    glEvalCoord1f((GLfloat) i/30.0F);
  glEnd();
  glPointSize(5.0);
  glColor4fv(couleurJaune());
  glBegin(GL_POINTS);
  for ( i = 0 ; i < aff ; i++ ) 
    glVertex3fv(&pts[i][0]);
  glEnd();
  glColor4fv(couleurMagenta());
  glPointSize(3.0);
  glBegin(GL_POINTS);
  bezier(&pl,40);
  glEnd();
  glDisable(GL_DEPTH_TEST);
  glColor4fv(couleurJaune());
  for ( i = 0 ; i < aff ; i++ )  {
    placeFontCursor(pts[i][0]+0.3F,pts[i][1]+0.3F,pts[i][2]+0.3F);
    simpleBitmapOutput("%d",i); }
  glPopMatrix();
  glFlush();
  glutSwapBuffers();
} 

void init(void) { 
  glClearColor(0.0,0.0,0.0,1.0);
  glMap1f(GL_MAP1_VERTEX_4,0.0,1.0,4,aff,&pts[0][0]);
  glEnable(GL_MAP1_VERTEX_4);
} 
  
void key(unsigned char key,int x,int y) {
  if ( keyManipulateur(key,x,y) )
    glutPostRedisplay();
    else
    switch ( key ) {
      case 0x0D :
        aff++;
        if ( aff == 7 )
          aff = 2;
        pl.n = aff;
        glMap1f(GL_MAP1_VERTEX_4,0.0,1.0,4,aff,&pts[0][0]);
        glutPostRedisplay();
        break; }
}

int main(int argc,char **argv) {
  
  pl.n = aff;
  pl.p =(coord_3D *) &pts[0][0];

  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
  glutInitWindowSize(300,300);
  glutInitWindowPosition(50,50);
  glutCreateWindow("Courbe de Bezier");
  init();
  creationMenuBasique();
  setParametresOrthoBasique(-5.0,5.0,-5.0,5.0,-500.0,500.0);
  setManipulateurDistance(1.0F);
  glutReshapeFunc(reshapeOrthoBasique);
  glutKeyboardFunc(key);
  glutSpecialFunc(specialBasique);
  glutMotionFunc(motionBasique);
  glutMouseFunc(sourisBasique);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}