> Fabrice Couvreur <mailto:fabrice1.couvreur@gmail.com>
> 24. Januar 2016 um 12:39
> Hello everyone,
> I tested the code and it does not work: I get one page with buttons 
> for animation is not working.
> thank you,
> Fabrice
>
> \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}}
You have nested definition which is wrong,the correct way is one of the 
following ones (2 or 3 are recommended):

\unexpanded\def\MyGraphics#1%
   {\startMPcode
      ...
    \stopMPcode}

or

\define[1]\MyGraphics
   {\startMPcode
      ...
    \stopMPcode}

or

\starttexdefinition unexpanded MyGraphics #1
     \startMPcode
         ...
     \stopMPcode
\stoptexdefinition

Wolfgang