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

  glMatrixMode(GL_PROJECTION);
  glPushMatrix();
    glLoadIdentity();
    glOrtho(0, winWidth, 0, winHeight, -1, 1);
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
      glLoadIdentity();
      glColor3f(1.0f, 1.0f, 0.0f);
      glRasterPos2i(x, y);
      len = strlen(msg);
      for (i=0; i<len; i++)
        glutBitmapCharacter(GLUT_BITMAP_HELVETICA_12, msg[i]);
    glPopMatrix();
  glPopMatrix();
}