Jeong Dal
21. Januar 2016 um 15:55
Thanks Hans, Wolfgang, Luigi

The new beta with Luatex 0.88 makes \fieldstacks and \startanimation work.
The following example of Wolfgang is now working well.

\def\MyGraphics#1{%
\unexpanded\def\MyGraphics#1{%
\startMPcode
path p,q;
p:=fullcircle scaled 72;
L:=length p;
N:=20;
q:=subpath (0,#1/N*L) of p;
draw q withcolor red;
fill fullcircle scaled 3 shifted point length q of q withcolor blue;
setbounds currentpicture to unitsquare shifted (-0.5,-0.5) scaled 75;
\stopMPcode}
\usemodule[animation]
\setupinteraction[state=start]

\starttext
\startanimation[menu=yes]
{\MyGraphics {5}}
{\MyGraphics {10}}
{\MyGraphics {15}}
{\MyGraphics {20}}
\stopanimation

\stoptext

One more question. Is there any convenient way to list \MyGraphics{#1}? I tried \dorecurse, but it just display figures one by one.  I also tried lua, but it stops with the error message  “unexpected symbol near ‘\'”.
\startanimation[menu=yes]
\dorecurse{20}{\expanded{\startframe \MyGraphics{\recurselevel} \stopframe}}
\stopanimation

Wolfgang