/* Une courbe de Bezier */
/* */
/* Auteur: Nicolas JANEY */
/* nicolas.janey@univ-fcomte.fr */
/* Novembre 2009 */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>
#include <GL/gl.h>
#include <GL/glu.h>
static float rx = 0.0F;
static float ry = 0.0F;
static float rz = 0.0F;
static GLfloat cyan[4] = { 0.0F,1.0F,1.0F,1.0F };
static GLfloat magenta[4] = { 1.0F,0.0F,1.0F,1.0F };
static GLfloat jaune[4] = { 1.0F,1.0F,0.0F,1.0F };
static GLfloat rouge[4] = { 1.0F,0.0F,0.0F,1.0F };
static GLfloat pts[8][4] = {
{-3.0,-3.0,-3.0,1.0},{-2.0, 3.0, 1.0,1.0},
{ 2.0,-3.0,-2.0,1.0},{ 3.0, 3.0,-3.0,1.0},
{-2.0,-1.0, 2.0,1.0},{ 3.0,-3.0,-1.0,1.0},
{ 2.0, 3.0, 3.0,1.0},{ 0.0, 0.0, 0.0,1.0} };
static int aff = 2;
static int nbp = 40;
typedef struct coord_3D {
GLfloat x,y,z,w; } coord_3D;
typedef struct lignePolygonale {
int n;
coord_3D *p; } lignePolygonale;
double power(double v,int p) {
return(( !v && !p ) ?
1.:
pow(v,(double) p));
}
void bezier(lignePolygonale *p,int n,lignePolygonale *b) {
int i,j;
float t,mt;
float *cn,fac;
b->n = n;
b->p =(coord_3D *) calloc(n,sizeof(coord_3D));
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;
for ( j = 0 ; j < p->n ; j++ ) {
fac = cn[j]*(float) power(t,j)*
(float) power(mt,p->n-1-j);
b->p[i].x += fac * p->p[j].x;
b->p[i].y += fac * p->p[j].y;
b->p[i].z += fac * p->p[j].z; } }
free(cn);
}
static lignePolygonale pl = { aff,(coord_3D *) &pts[0][0] };
void display(void) {
int i;
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glRotatef(rx,1.0F,0.0F,0.0F);
glRotatef(ry,0.0F,1.0F,0.0F);
glRotatef(rz,0.0F,0.0F,1.0F);
glPointSize(5.0);
glColor4fv(jaune);
glBegin(GL_POINTS);
for( i = 0 ; i < aff ; i++ )
glVertex3fv(&pts[i][0]);
glEnd();
glColor4fv(rouge);
glBegin(GL_LINE_STRIP);
for( i = 0 ; i < aff ; i++ )
glVertex3fv(&pts[i][0]);
glEnd();
glColor4fv(magenta);
glPointSize(3.0);
lignePolygonale bz;
bezier(&pl,nbp,&bz);
glBegin(GL_POINTS);
for ( i = 0 ; i < bz.n ; i++ )
glVertex3fv((GLfloat *)&bz.p[i]);
glEnd();
free(bz.p);
glPopMatrix();
glFlush();
glutSwapBuffers();
int error = glGetError();
if ( error != GL_NO_ERROR )
printf("Erreur OpenGL\n",error);
}
/* Fonction executee lorsqu'aucun evenement */
/* n'est en file d'attente */
void idle(void) {
rx += 0.4256F;
ry += 0.6117F;
rz += 0.4174F;
glutPostRedisplay() ;
}
/* Fonction executee lors d'un changement */
/* de la taille de la fenetre OpenGL */
void reshape(int x,int y) {
glViewport(0,0,x,y);
glMatrixMode(GL_PROJECTION) ;
glLoadIdentity() ;
gluPerspective(50.0F,(float) x/y,1.0,40.0) ;
glMatrixMode(GL_MODELVIEW) ;
glLoadIdentity() ;
gluLookAt(0.0,0.0,10.0,0.0,0.0,0.0,0.0,1.0,0.0);
}
/* Fonction executee lors de l'appui */
/* d'une touche de curseur ou d'une touche */
/* page up ou page down */
void special(int key,int x,int y) {
switch(key) {
case GLUT_KEY_UP :
rx++;
glutPostRedisplay() ;
break;
case GLUT_KEY_DOWN :
rx--;
glutPostRedisplay() ;
break;
case GLUT_KEY_LEFT :
ry++;
glutPostRedisplay() ;
break;
case GLUT_KEY_RIGHT :
ry--;
glutPostRedisplay() ;
break;
case GLUT_KEY_PAGE_UP :
rz++;
glutPostRedisplay() ;
break;
case GLUT_KEY_PAGE_DOWN :
rz--;
glutPostRedisplay() ;
break; }
}
void myinit(void) {
glClearColor(0.0,0.0,0.0,1.0);
glEnable(GL_DEPTH_TEST);
glShadeModel(GL_FLAT);
glDepthFunc(GL_LESS);
glEnable(GL_AUTO_NORMAL);
glEnable(GL_NORMALIZE);
}
void keyboard(unsigned char key,int x,int y) {
switch ( key ) {
case 43 :
nbp++;
glutPostRedisplay();
break;
case 45 :
nbp--;
if ( nbp < 2 )
nbp = 2;
glutPostRedisplay();
break;
case 0x1B :
exit(0);
break;
case 0x20 :
{ static int anim = 0;
anim = !anim;
glutIdleFunc(( anim ) ? idle : NULL); }
break;
case 0x0D :
aff++;
if ( aff == 9 )
aff = 2;
pl.n = aff;
glutPostRedisplay();
break; }
}
int main(int argc,char **argv) {
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_RGBA|GLUT_DEPTH|GLUT_DOUBLE);
glutInitWindowSize(300,300);
glutInitWindowPosition(50,50);
glutCreateWindow("Courbe de Bezier");
myinit();
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutSpecialFunc(special);
glutDisplayFunc(display);
glutMainLoop();
return(0);
}
RETOUR