defaultfont := "cmr12";
 defaultscale := 12pt /fontsize defaultfont;
 prologues := 3;
 outputformat := "svg";
 %пример использования slanted
 beginfig(1) ;
  numeric u;
  u = 0.8mm;
  cutdraw (0u,0u)--(20u,0u)--(20u,30u){dir 90}..
      {dir -90}(17u,30u)--(17u,3u)--(0u,3u)
  withpen pencircle scaled 0.5u;
  drawdblarrow (23u,10u)--(23u,1u);
  label.rt("h",1/2[(23u,10u),(23u,1u)]);
  drawdblarrow (30u,30u)--(30u,1u);
  label.lft("H",1/2[(30u,30u),(30u,1u)]);
  picture Base;
  Base:=currentpicture;
  clearit;
  fill (15u,0u)--(20u,0u)--(20u,20u)--(17u,20u)--(17u,3u)--(15u,3u)--cycle
   withcolor 0.7white;
  draw Base;
  draw ((12u,20u)--(20u,20u));
  draw ((12u,10u)--(20u,10u));
  drawdblarrow ((14u,20u)--(14u,10u));
  label.lft("d",(14u,16u));
  picture Slant;
  Slant=currentpicture;
  clearit;
  fill (5u,0u)--(20u,0u)--(20u,10u)--(17u,10u)--(17u,3u)--(5u,3u)--cycle
  withcolor 0.7white;
  draw Base;
 % Собственно говоря, приер линейных преобразований здесь.
  draw Slant yscaled 2/3 slanted 1/2 shifted (40u,0u);
 endfig;