/* Auteur: Nicolas JANEY           */
/* nicolas.janey@univ-fcomte.fr    */
/* Septembre 2004                  */
/* Un programme OpenGL tout simple */

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

void scene(void) {
  glPushMatrix() ;
  glBegin(GL_POLYGON) ;
  glVertex2f(-0.5F,-0.5F) ;
  glVertex2f(-0.5F,0.5F) ;
  glVertex2f(0.5F,0.5F) ;
  glVertex2f(0.5F,-0.5F) ;
  glEnd() ;
  glPopMatrix() ;
}

void reshape(int x,int y) {
  glViewport(0,0,x,y); 
  glMatrixMode(GL_PROJECTION) ;
  glLoadIdentity() ;
  glOrtho(-1.0,1.0,(double) -y/x,(double) y/x,-1.0,1.0) ;
  glMatrixMode(GL_MODELVIEW) ;
  glLoadIdentity() ;
}

void display(void) {
  glClear(GL_COLOR_BUFFER_BIT) ;
  glPushMatrix() ;
  scene();
  glPopMatrix() ;
  glFlush();
}

int main(int argc,char **argv) {
  glutInit(&argc,argv);
  glutInitDisplayMode(GLUT_RGBA|GLUT_SINGLE);
  glutInitWindowSize(200,200); 
  glutInitWindowPosition(50,50); 
  glutCreateWindow("Simple"); 
  glutReshapeFunc(reshape);
  glutDisplayFunc(display);
  glutMainLoop();
  return(0);
}