Block 1:
   glBegin(GL_POLYGON);
      glVertex3f(20.0, 20.0, 0.0);
      glVertex3f(80.0, 20.0, 0.0);
      glVertex3f(40.0, 40.0, 0.0);
      glVertex3f(20.0, 80.0, 0.0);
   glEnd();

Block 2:
   glBegin(GL_POLYGON);
      glVertex3f(80.0, 20.0, 0.0);
      glVertex3f(40.0, 40.0, 0.0);
      glVertex3f(20.0, 80.0, 0.0);
      glVertex3f(20.0, 20.0, 0.0);
   glEnd();

Block 3:
   glBegin(GL_POLYGON);
      glColor3f(0.0, 0.0, 0.0);
      glVertex3f(80.0, 20.0, 0.0);
      glColor3f(1.0, 0.0, 0.0);
      glVertex3f(40.0, 40.0, 0.0);
      glColor3f(0.0, 0.0, 0.0);
      glVertex3f(20.0, 80.0, 0.0);
      glVertex3f(20.0, 20.0, 0.0);
   glEnd();

Block 4:
   glBegin(GL_POLYGON);
      glVertex3f(50, 10, 0);
      glVertex3f(40, 50, 0);
      glVertex3f(10, 60, 0);
      glVertex3f(90, 60, 0);
      glVertex3f(60, 50, 0);
   glEnd();

Block 5:
   glBegin(GL_POLYGON);
      glColor3f(0.0, 0.0, 0.0); 
      glVertex3f(20.0, 20.0, 0.0);
      glVertex3f(50.0, 20.0, 0.0);
      glVertex3f(80.0, 50.0, 0.0);
      glVertex3f(80.0, 80.0, 0.0);
      glColor3f(1.0, 0.0, 0.0); 
      glVertex3f(20.0, 80.0, 0.0);
   glEnd();

Block 6:
   glBegin(GL_POLYGON);
      glColor3f(0.0, 0.0, 0.0); 
      glVertex3f(50.0, 20.0, 0.0);
      glVertex3f(80.0, 50.0, 0.0);
      glVertex3f(80.0, 80.0, 0.0);
      glColor3f(1.0, 0.0, 0.0); 
      glVertex3f(20.0, 80.0, 0.0);
      glColor3f(0.0, 0.0, 0.0); 
      glVertex3f(20.0, 20.0, 0.0);
   glEnd();