china.pl

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/********************************************************************
    Constraint-based Graphical Programming in B-Prolog
    %
    draw the Chinese National flag
*********************************************************************/
go:-
    china(Os),
    cgJava(china,Os).

china([R|Stars]):-
    cgDefaultWindow(Win),
    Win^leftMargin #= LM,
    Win^topMargin #= TM,
    cgRectangle(R), R^color #= red,
    Stars=[S0,S1,S2,S3,S4],
    cgStars(Stars), cgSame(Stars,color,yellow), cgSame(Stars,n,5),
    cgSame([S1,S2,S3,S4],diameter),
    %
    2*R^width #= 3*R^height,
    R^width #> 250,
    %
    5*S0^diameter #= R^width,
    3*S1^diameter #= S0^diameter,
    %
    5*(S0^centerX-LM) #= R^width,
    4*(S0^centerY-TM) #= R^height,
    S0^angle0 #= 90,

    3*(S1^centerX-LM) #= R^width,
    10*(S1^centerY-TM) #= R^height,
    S1^angle0 #= 70,

    25*(S2^centerX-LM) #= 10*R^width,
    5*(S2^centerY-TM) #= R^height,
    S2^angle0 #= 45,

    25*(S3^centerX-LM) #= 10*R^width,
    3*(S3^centerY-TM) #= R^height,
    S3^angle0 #= 90,

    3*(S4^centerX-LM) #= R^width,
    21*(S4^centerY-TM) #=< 10*R^height,
    23*(S4^centerY-TM) #> 10*R^height,
    S4^angle0 #= 65.