Hello,
I want to reproduce this figure.


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In the example below, it seemed to me that he had to write  dir(180-angle(1,0.5)), but not.

\starttext

\startMPcode

path p ;
p := (3.5cm,-1.5cm)--(0cm,0.25cm)--1.2cm*dir(180-angle(1,0.5)) ;

draw p dashed evenly withcolor 0.625white;

draw p reflectedabout ((3.75cm,-1.5cm),(3.75cm,1.5cm)) dashed evenly withcolor 0.625white ;

draw (-1cm,-1.5cm)--(8.5cm,-1.5cm)--(8.5cm,0.9cm)--(-1cm,0.9cm)--cycle withcolor 0.625white ;

for i=0 upto 14 :
        draw unitsquare scaled 0.5cm shifted(i/2*cm,0*cm) ;
endfor ;

for i=0 upto 10 :
        draw unitsquare scaled 0.5cm shifted((i+2)/2*cm,-1/2*cm) ;
endfor ;

for i=0 upto 6 :
        draw unitsquare scaled 0.5cm shifted((i+4)/2*cm,-1*cm) ;
endfor ;

for i=0 upto 2 :
        draw unitsquare scaled 0.5cm shifted((i+6)/2*cm,-3/2*cm) ;
endfor ;

\stopMPcode

\stoptext


Thank you.