Now we need to specify the vertices for the lines. This is done with
glVertex2f( -0.7, -0.7 ); glVertex2f( 0.7, -0.7 ); glVertex2f( 0.7, 0.7 ); glVertex2f( -0.7, 0.7 ); glVertex2f( -0.7, -0.7 );