static void drawText(GLfloat x, GLfloat y, char * msg)
{
  int   i, len;

  glPushMatrix();
    glLoadIdentity();
    glTranslatef( 0.0, 0.0, -10.0 ); /* -10 from 10 in frustum */
    glColor3f(1.0f, 1.0f, 0.0f);
    glRasterPos2f(x, y); /* relative to -1.0 1.0 in frustum */
    len = strlen(msg);
    for (i=0; i<len; i++)
      glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18, msg[i]);
  glPopMatrix();
}