#include <OpenGL/gl.h>  // pour MacOSX
#include <OpenGL/glu.h> // pour MacOSX
#include <GLUT/glut.h>  // pour MacOSX

// #include "glut.h"    // pour PC

/*
Compilation sur MacOSX :
gcc -framework OpenGL -framework GLUT -framework Cocoa -o transf transf.c

Compilation sur PC :
gcc transf.c -o transf -L/usr/X11R6/include/GL -L/usr/X11R6/lib -lGL -lGLU -lglut -lm -lX11

22/04/04 - Didier STRAUS - Info. graphique - Carre qui tourne en OpenGL
Un carre qui tourne sur lui meme et qui decrit un cercle.
http://www.Software-DS.com
*/

/* variables globales */
int a=0,b=0;
int inca=2,incb=2;

/* prototypes */
void affichage();
void clavier(unsigned char touche,int x,int y);
void reshape(int x,int y);
void idle();


/* main */
int main(int argc,char **argv) {
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutInitWindowPosition(200,200);
glutInitWindowSize(500,500);
glutCreateWindow("transf - DS");

glClearColor(0,0,0,0);
glColor3f(1,1,1);
glShadeModel(GL_FLAT);

glutDisplayFunc(affichage);
glutKeyboardFunc(clavier);
glutReshapeFunc(reshape);
glutIdleFunc(idle);

glutMainLoop();
return 0;
}

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

void affichage() {
 glClear(GL_COLOR_BUFFER_BIT);

 // dessin
 glLoadIdentity();
 glRotatef(b,0,0,1);
 glTranslatef(0.5,0,0);
 glRotatef(a,0,0,1);

 glBegin(GL_POLYGON);
 glVertex3f(-0.2,-0.2,0);
 glVertex3f( 0.2,-0.2,0);
 glVertex3f( 0.2, 0.2,0);
 glVertex3f(-0.2, 0.2,0);
 glEnd();

 glFlush();
 glutSwapBuffers();
} /* affichage */

void clavier(unsigned char touche,int x,int y) {
switch(touche) {
 case 'a':
  inca++;
  if (inca>10)
   inca=10;
  glutPostRedisplay();
  break;

case 'A':
  inca--;
  if (inca<(-10))
   inca=-10;
  glutPostRedisplay();
  break;

case 'b':
  incb++;
  if (incb>10)
   incb=10;
  glutPostRedisplay();
  break;

case 'B':
  incb--;
  if (incb<(-10))
   incb=-10;
  glutPostRedisplay();
  break;

case 'q':
 exit(0);
}

} /* clavier */

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

void reshape(int x,int y) {
 if (x<y)
  glViewport(0,(y-x)/2,x,x);
 else
  glViewport((x-y)/2,0,y,y);  
} /* reshape */

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

void idle() {
 a+=inca;
 if (a>360)
  a-=360;
 b+=incb;
 if (b>360)
  b-=360;
 
 glutPostRedisplay();
} /* idle */