Re: [NTG-context] simplifying repeated macro calls in metafun

23 Jun 2021

      Dear Otared,
...
Regarding the way Aditya uses \startuseMPgraphic, it is also very instructive. 
Dalyoung, can you also share the animation example for the foldings ? I am sure we are a few on the list to learn something…
1. Here is the working sample of animation using \processMPbuffer which I did before. You can see it using adobe reader.

\startbuffer[UDBasic]
  pair A,B,C,D;
  pair E, F, G, H;
  path p,q;
  numeric ang,maxNum;
  u:=1in;
  A=(.95*TextWidth,u); B=(0,u); C=(0,0); D=(.95*TextWidth,0);
  p := A--B--C--D;
  q := (TextWidth,1.5u)--(0,1.5u)--(0,-.5u)--(TextWidth,-.5u)--cycle;
  z0=(.1u,0);

   vardef nextPt (expr M,N) = 
   if ypart(N) = 0: 
       H := whatever[N, N + dir(.5*angle(M-N))*u] = whatever[A,B];
   else:
       H := whatever[N, N + dir(.5*angle(M-N))*u] = whatever[C,D];
   fi;
   H
   enddef;

   def grayUD(expr i) =
      draw G -- if ypart(B)=ypart(G): B -- C else: C -- B fi --z[i];
      filldraw z[i]+2*(G-z[i])*u -- z[i] -- z[i+1] -- z[i+1]+(G-z[i])*u -- cycle withcolor .75white; 
      draw G -- z[i+1] dashed evenly;
      draw z[0] for k=0 upto i: --z[k] endfor dashed evenly;
      clip currentpicture to q;
      setbounds currentpicture to boundingbox q;
   enddef;

   def linesUD(expr i) =
      draw p;
      draw z0 for k=0 upto i+1: --z[k] endfor dashed evenly;
      setbounds currentpicture to boundingbox q;
   enddef;
\stopbuffer

\startbuffer[UDpts]
   ang := 40;
   z[1] = whatever[z[0], z[0]+dir(ang)*u] = whatever[A,B];
   G := whatever[z[0], z[0]+dir(2*ang)*u] = whatever[A,B];
   for k = 2 upto 20:
      z[k] = nextPt(z[k-2],z[k-1]);
      maxNum := k;
      exitif xpart(z[k]) > TextWidth;
   endfor;
\stopbuffer
\startbuffer[UD0]
   draw p;
   setbounds currentpicture to boundingbox q;
\stopbuffer
\startbuffer[UD1]
   grayUD(0);
\stopbuffer
\startbuffer[UD11]
   linesUD(0);
\stopbuffer
\startbuffer[UD2]
   G := z0;
   grayUD(1)
\stopbuffer
\startbuffer[UD21]
   linesUD(1);
\stopbuffer
\startbuffer[UD3]
   G := z1;
   grayUD(2);
\stopbuffer
\startbuffer[UD31]
   linesUD(2);
\stopbuffer
\startbuffer[UD4]
   G := z2;
   grayUD(3);
\stopbuffer
\startbuffer[UD41]
   linesUD(3);
\stopbuffer
\startbuffer[UD5]
   G := z3;
   grayUD(4);
\stopbuffer
\startbuffer[UD51]
   linesUD(4);
\stopbuffer
\startbuffer[UDFinal]
draw p;
draw z0--z1--z2--z3--z4--z5--z6--z7--z8 dashed evenly;
setbounds currentpicture to boundingbox q;
\stopbuffer

\setupinteraction[state=start]
\usemodule[animation]
\starttext
\startanimation[menu=yes]
{\processMPbuffer[UDBasic,UDpts,UD0]}
{\processMPbuffer[UDBasic,UDpts,UD1]}
{\processMPbuffer[UDBasic,UDpts,UD11]}
{\processMPbuffer[UDBasic,UDpts,UD2]}
{\processMPbuffer[UDBasic,UDpts,UD21]}
{\processMPbuffer[UDBasic,UDpts,UD3]}
{\processMPbuffer[UDBasic,UDpts,UD31]}
{\processMPbuffer[UDBasic,UDpts,UD4]}
{\processMPbuffer[UDBasic,UDpts,UD41]}
{\processMPbuffer[UDBasic,UDpts,UD5]}
{\processMPbuffer[UDBasic,UDpts,UD51]}
{\processMPbuffer[UDBasic,UDpts,UDFinal]}
\stopanimation
\stoptext

Now, I am trying to do the same thing using \startuseMPgraphic, but I don’t the correct result yet.
Using \startuseMPgraphic, and \dorecurse, the code is simpler. But, it seems to me that \startanimation … \stopanimation is not working with \dorecurse{}{} …
It just list all the graphics.
Any hint is welcome.

\startMPinitializations%{UDBasic}
  pair A,B,C,D;
  pair E, F, G, H;
  path p,q;
  numeric ang,maxNum;

  numeric n; %AM Added

  u:=1in;
  A=(.95*TextWidth,u); B=(0,u); C=(0,0); D=(.95*TextWidth,0);
  p := A--B--C--D;
  q := (TextWidth,1.5u)--(0,1.5u)--(0,-.5u)--(TextWidth,-.5u)--cycle;
  z0=(.1u,0);

   vardef nextPt (expr M,N) = 
   if ypart(N) = 0: 
       H := whatever[N, N + dir(.5*angle(M-N))*u] = whatever[A,B];
   else:
       H := whatever[N, N + dir(.5*angle(M-N))*u] = whatever[C,D];
   fi;
   H
   enddef;

   def grayUD(expr i) =
      draw G -- if ypart(B)=ypart(G): B -- C else: C -- B fi --z[i];
      filldraw z[i]+2*(G-z[i])*u -- z[i] -- z[i+1] -- z[i+1]+(G-z[i])*u -- cycle withcolor .75white; 
      draw G -- z[i+1] dashed evenly;
      draw z[0] for k=0 upto i: --z[k] endfor dashed evenly;
      clip currentpicture to q;
   enddef;

   def linesUD(expr i) =
      draw p;
      draw z0 for k=0 upto i+1: --z[k] endfor dashed evenly;

      % AM: removed. Set in in the main code
      % setbounds currentpicture to boundingbox q;
   enddef;

   ang := 40;
   z[1] = whatever[z[0], z[0]+dir(ang)*u] = whatever[A,B];

   % AM: Changed next line from G to z[-1]
   z[-1] = whatever[z[0], z[0]+dir(2*ang)*u] = whatever[A,B];
   for k = 2 upto 20:
      z[k] = nextPt(z[k-2],z[k-1]);
      maxNum := k;
      exitif xpart(z[k]) > TextWidth;
   endfor;

\stopMPinitializations

\startuseMPgraphic{foldUD}{num}
   numeric n;
   n := \MPvar{num}-1;
   G := z[n-1];
   grayUD(n);
\stopuseMPgraphic
\startuseMPgraphic{dotLines}{num}
   numeric n;
   n := \MPvar{num}-1;
   linesUD(n);
\stopuseMPgraphic

\setupinteraction[state=start]
\usemodule[animation]
\starttext
\startanimation[menu=yes]
\dorecurse{7}
{
 {\useMPgraphic{foldUD}{num=\recurselevel}}
 {\useMPgraphic{dotLines}{num=\recurselevel}}
}
\stopanimation
\stoptext

Best regards,

Dalyoung

Re: [NTG-context] simplifying repeated macro calls in metafun

Jeong Dal