prologues := 2 ;

beginfig(1)

    numeric u ;
    u = 1 cm ;

    color yellow ;
    color orange ;

    yellow = red + green ;
    orange = red + 1/3 green ;

    for i = 10 downto 0 :
        fill (0,0)--(i*u,0)--(i*u,i*u)--cycle withcolor (i/10)[yellow,orange] ;
    endfor ;

    for i = 200 downto 0 :
        fill (0,0)--(0,i*u/20)--(i*u/20,i*u/20)--cycle withcolor (i/200)[orange,yellow] ;
    endfor ;

    draw (0,0)--(10u,0)--(10u,10u)--cycle ;
    draw (0,0)--(0,10u)--(10u,10u) ;

endfig ;

end