Main

  janelaMain=glutCreateWindow("OpenGL");
  glutReshapeFunc(myReshapeMain);
  glutDisplayFunc(displayMain);
  glutKeyboardFunc(keyboard);
  glutTimerFunc(30, Timer, 0);
  glutSpecialFunc(special);
  glutSpecialUpFunc(specialUp);

  myInit();

  janela1=glutCreateSubWindow(janelaMain,10,10,10,10);// dentro do Reshape da main os valores são alterados
  glutReshapeFunc(myReshapeJanela1);
  glutDisplayFunc(display);
	glutKeyboardFunc(keyboard);
  glutSpecialFunc(special);
  glutSpecialUpFunc(specialUp);

  myInit();

  janela2=glutCreateSubWindow(janelaMain,300,20,30,30);// dentro do Reshape da main os valores são alterados
  glutReshapeFunc(myReshapeJanela2);
  glutDisplayFunc(display);
  glutKeyboardFunc(keyboard);
  glutSpecialFunc(special);
  glutSpecialUpFunc(specialUp);

  myInit();


  glutMainLoop();

Reshapes

#define GAP       40

void myReshapeMain(int w, int h)
{	
    GLint tamJan,altJan;

    tamJan=(w-3*GAP)/2;
    altJan=h-2*GAP;

	  glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    gluOrtho2D(0,w,h,0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    glutSetWindow(janela1);
    glutPositionWindow(GAP,GAP);
    glutReshapeWindow(tamJan,altJan);
    glutSetWindow(janela2);
    glutPositionWindow(GAP+tamJan+GAP,GAP);
    glutReshapeWindow(tamJan,altJan);

}


void myReshapeJanela1(int w, int h)
{	
	glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();


    gluPerspective(60, (GLfloat)w/h, 1,100);
    gluLookAt(0,30,30, 0,0,0, 0,0,1);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void myReshapeJanela2(int w, int h)
{	
    escala=5;
	  glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    if (w <= h)
        glOrtho(-10.0 * (GLfloat) escala, 10.0 * (GLfloat) escala, -10.0  * (GLfloat) escala* (GLfloat) h / (GLfloat) w,
            10.0  * (GLfloat) escala* (GLfloat) h / (GLfloat) w, -50.0, 50.0);
    else
        glOrtho(-10.0  * (GLfloat) escala * (GLfloat) w / (GLfloat) h,
            10.0  * (GLfloat) escala * (GLfloat) w / (GLfloat) h, -10.0 * (GLfloat) escala, 10.0 * (GLfloat) escala, -50.0, 50.0);
    glRotatef(45,-1,0,0);
    glRotatef(45,0,0,1);
  
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

Redisplay All

void RedisplayAll()
{
glutSetWindow(janelaMain);
glutPostRedisplay();
glutSetWindow(janela1);
glutPostRedisplay();
glutSetWindow(janela2);
glutPostRedisplay();
}

Strings

/* font pode ser
GLUT_BITMAP_8_BY_13
GLUT_BITMAP_9_BY_15
GLUT_BITMAP_TIMES_ROMAN_10
GLUT_BITMAP_TIMES_ROMAN_24
GLUT_BITMAP_HELVETICA_10
GLUT_BITMAP_HELVETICA_12
GLUT_BITMAP_HELVETICA_18
*/

void drawstr(GLfloat x, GLfloat y, void *font, char* format, ...)
{
  va_list args;
  char buffer[255], *s;

  va_start(args, format);
  vsprintf(buffer, format, args);
  va_end(args);

  glRasterPos2f(x, y);
  for (s = buffer; *s; s++)
    glutBitmapCharacter(font, *s);
}


/* font pode ser
GLUT_STROKE_ROMAN
GLUT_STROKE_MONO_ROMAN
*/

void drawstroke(GLfloat x, GLfloat y, GLfloat z, void *font, char* format, ...)
{
  va_list args;
  char buffer[255], *s;

  va_start(args, format);
  vsprintf(buffer, format, args);
  va_end(args);

  glTranslatef(x, y, z);

  for (s = buffer; *s; s++)
    glutStrokeCharacter(font, *s);
}

Exemplo de desenho de strings

drawstr(5,10, GLUT_BITMAP_8_BY_13,"Texto Bitmap");
glPushMatrix();
glScalef(0.3,-0.3,0.3);
drawstroke(505,-100, 0, GLUT_STROKE_ROMAN,"Texto Stroke");
glPopMatrix();