On utilise la fonction gluLookAt de la librairie glu. L'axe de la verticale est l'axe (0.0, 1.0, 0.0).
/* Auteur: Nicolas JANEY */
/* nicolas.janey@univ-fcomte.fr */
/* Octobre 2008 */
/* Un programme OpenGL de placement */
/* d'une camera au sein d'une scene */
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <GL/glut.h>
#include <GL/gl.h>
#include <GL/glu.h>
/* Variables globales */
static double dist;
/* Fonction de modelisation de la scene */
void element(GLfloat *c1,GLfloat *c2,GLfloat *c3) {
glPushMatrix();
glMaterialfv(GL_FRONT,GL_DIFFUSE,c1);
glutSolidTorus(0.75,10.0,90,90);
glPushMatrix();
glMaterialfv(GL_FRONT,GL_DIFFUSE,c2);
glTranslatef(6.0F,0.0F,0.0F);
glScalef(12.0F,1.5F,1.5F);
glutSolidCube(1.0);
glPopMatrix();
glPushMatrix();
glMaterialfv(GL_FRONT,GL_DIFFUSE,c3);
glTranslatef(-6.0F,0.0F,0.0F);
glScalef(12.0F,1.5F,1.5F);
glutSolidCube(1.0);
glPopMatrix();
glPopMatrix();
}
void scene(void) {
const GLfloat l_pos0[] = { 1.0F,1.0F,1.0F,0.0F };
const GLfloat l_pos1[] = { -1.0F,1.0F,1.0F,0.0F };
const GLfloat blanc[4] = { 1.0F,1.0F,1.0F,1.0F };
const GLfloat gris[4] = { 0.6F,0.6F,0.6F,1.0F };
const GLfloat rouge[4] = { 1.0F,0.0F,0.0F,1.0F };
const GLfloat vert[4] = { 0.0F,1.0F,0.0F,1.0F };
const GLfloat bleu[4] = { 0.0F,0.0F,1.0F,1.0F };
const GLfloat jaune[4] = { 1.0F,1.0F,0.0F,1.0F };
const GLfloat cyan[4] = { 0.0F,1.0F,1.0F,1.0F };
const GLfloat magenta[4] = { 1.0F,0.0F,1.0F,1.0F };
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_LIGHT1);
glEnable(GL_DEPTH_TEST);
glEnable(GL_NORMALIZE);
glLightfv(GL_LIGHT0,GL_POSITION,l_pos0);
glLightfv(GL_LIGHT1,GL_POSITION,l_pos1);
glLightfv(GL_LIGHT0,GL_DIFFUSE,gris);
glLightfv(GL_LIGHT1,GL_DIFFUSE,gris);
glPushMatrix();
element((GLfloat *) blanc,(GLfloat *) rouge,(GLfloat *) jaune);
glPopMatrix();
glPushMatrix();
glRotatef(90.0F,1.0F,0.0F,0.0F);
glRotatef(90.0F,0.0F,0.0F,1.0F);
element((GLfloat *) blanc,(GLfloat *) vert,(GLfloat *) cyan);
glPopMatrix();
glPushMatrix();
glRotatef(90.0F,0.0F,1.0F,0.0F);
glRotatef(90.0F,0.0F,0.0F,1.0F);
element((GLfloat *) blanc,(GLfloat *) bleu,(GLfloat *) magenta);
glPopMatrix();
}
/* Fonction executee lors d'un rafraichissement */
/* de la fenetre de dessin */
void display(void) {
glClearColor(0.6F,0.6F,0.6F,1.0F) ;
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT) ;
/* Affichage de la scene */
glPushMatrix();
glTranslatef(-100.0F,-100.0F,-100.0F);
scene();
glPopMatrix();
glFlush();
glutSwapBuffers();
int error = glGetError();
if ( error != GL_NO_ERROR )
printf("Attention, erreur OpenGL %d\n",error);
}
/* Fonction executee lors d'un changement */
/* de la taille de la fenetre OpenGL */
/* Configuration d'une camera de visualisation */
/* en projection en perspective */
void reshape(int tx,int ty) {
dist = 100.0*sqrt(3.0);
glViewport(0,0,tx,ty);
double ratio =(double) tx/ty;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(8.0,ratio,dist-15.0,dist+15.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt( 0.0, 0.0, 0.0,
-100.0,-100.0,-100.0,
0.0, 1.0, 0.0);
}
/* Fonction executee lors de la frappe */
/* d'une touche alphanumerique du clavier */
void keyboard(unsigned char key,int x,int y) {
switch ( key ) {
case 0x1B : exit(0); }
}
/* Fonction principale */
int main(int argc,char **argv) {
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE|GLUT_DEPTH);
glutInitWindowSize(250,250);
glutInitWindowPosition(50,50);
glutCreateWindow("Placement de camera");
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutDisplayFunc(display);
glutMainLoop();
return(0);
}
RETOUR