%фрактальная лесопосадка  beginfig(1) ;    u:=1mm; branchrotation := 50;    offset := 180-branchrotation;    thinning := 0.7;    shortening := 0.8;    def drawit(expr p, linethickness,col) =      draw p withpen pencircle scaled linethickness withcolor col;    enddef;    %A- основание B- направление роста, n - число бранчей,    %size толщина дерева, col цвет    vardef tree(expr A,B,n,size,col) =      save C,D,thickness; pair C,D;      thickness := size;      C := shortening[B, A rotatedaround(B,        offset+uniformdeviate(branchrotation))];      D := shortening[B, A rotatedaround(B,        -offset-uniformdeviate(branchrotation))];      if n>0:        drawit(A--B, thickness, col);        thickness := thinning*thickness;        tree(B, C, n-1, thickness,col);        tree(B, D, n-1, thickness,col);      else:        drawit(A--B,thickness,col);        thickness := thinning*thickness;        drawit(B--C, thickness,col);        drawit(B--D, thickness,col);      fi;    enddef;    numeric nbr,nx,ny,ell,size;    color col;    nx:=10;ny:=5;    pair A;    for ix:=1 upto nx:      for iy:=1 upto ny:        nbr:=4+uniformdeviate 5;        ell:=nbr*u;        x:=ix*(1+1/20*normaldeviate);        y:=iy*(1+1/20*normaldeviate);        A:=(20u*(x+y*sqrt(2)/2),20u*y*sqrt(2)/2);        size:=ell/5;        col:=(uniformdeviate 1,uniformdeviate 1,uniformdeviate 1);        show ix,iy,A,ell,nbr,size,col;        tree(A, A+(0,ell), nbr, size,col);      endfor;    endfor;  endfig;