\startanimation and \dorecurse

\startanimation and \dorecurse

[Jeong Dal]

Hi,

I tested the following simple code to generate enlarging circles as a test of animation.
But it just draw 5 circles in a row.

\usemodule[animation]
\setupinteraction[state=start]
\startbuffer[Circles]
numeric u; u:= 1cm;
draw fullcircle scaled \MPrawvar{Circles}{s}u;
\stopbuffer
\starttext
\startanimation
{ \dorecurse{5}{%
\setupMPvariables[Circles][s=\recurselevel]
\processMPbuffer [Circles]
}}
\stopanimation
\stoptext

It seems to me that \startanimation just treat the figures 
{\dorecurse … } as just one figure.

Is there a way to treat it 5 figures to generate animation? 

Thank you for reading.

Best regards,

Dalyoung


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Re: \startanimation and \dorecurse

[Wolfgang Schuster]

> Am 20.10.2014 um 13:32 schrieb Jeong Dal <haksan@me.com>:
> 
> Hi,
> 
> I tested the following simple code to generate enlarging circles as a test of animation.
> But it just draw 5 circles in a row.
> 
> \usemodule[animation]
> \setupinteraction[state=start]
> \startbuffer[Circles]
> numeric u; u:= 1cm;
> draw fullcircle scaled \MPrawvar{Circles}{s}u;
> \stopbuffer
> \starttext
> \startanimation
> { \dorecurse{5}{%
> \setupMPvariables[Circles][s=\recurselevel]
> \processMPbuffer [Circles]
> }}
> \stopanimation
> \stoptext
> 
> It seems to me that \startanimation just treat the figures 
> {\dorecurse … } as just one figure.
> 
> Is there a way to treat it 5 figures to generate animation? 
> 
> Thank you for reading.

1. You have to expand the \recurselevel value.

2. Don’t put braces around \dorecurse because when \startanimation sees a opening braces it assumes you want to put each frame into a group of braces.


Variant 1:

\usemodule[animation]

\setupinteraction[state=start]

\startbuffer[Circles]
numeric u; u:= 1cm;
draw fullcircle scaled \MPrawvar{Circles}{s}u;
\stopbuffer

\starttext

\startanimation
\dorecurse{5}
  {\startexpanded
     \startframe
       \setupMPvariables[Circles][s=\recurselevel]
       \processMPbuffer [Circles]
     \stopframe
   \stopexpanded}
\stopanimation

\stoptext


Variant 2:

\usemodule[animation]

\setupinteraction[state=start]

\startuseMPgraphic{Circles}{s}
numeric u; u:= 1cm;
draw fullcircle scaled \MPvar{s}u;
\stopuseMPgraphic

\starttext

\startanimation
\dorecurse{5}
  {\startexpanded
     \frame{\useMPgraphic{Circles}{s=\recurselevel}}%
   \stopexpanded}
\stopanimation

\stoptext

Wolfgang
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Re: \startanimation and \dorecurse

[Jeong Dal]

Dear Wolfgang,

Thank you for a nice solution.

I applied your method to produce an animation which draw a circle using the following:

%%%%%%%%
\usemodule[animation]
\setupinteraction[state=start]
\startuseMPgraphic{Circles}{s}
numeric sn, L, N;
path p, q;
p := fullcircle scaled 72;
L:=length p;
N:=20;
sn:= \MPvar{s};
q := subpath (0, sn/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;
\stopuseMPgraphic
\starttext
\startanimation
\dorecurse{20}
{\startexpanded
%\setupMPvariables[Circles][s]
\useMPgraphic{Circles}{s=\recurselevel}
\stopexpanded}
\stopanimation
\stoptext
%%%%%%%%%%

However, it just draw 20 figures instead of making an animation.

Would you please tell me what is wrong in the above code?

Thank you.

Best regards,

Dalyoung
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Re: \startanimation and \dorecurse

[Wolfgang Schuster]

> Am 21.10.2014 um 14:08 schrieb Jeong Dal <haksan@me.com>:
> 
> Dear Wolfgang,
> 
> Thank you for a nice solution.
> 
> I applied your method to produce an animation which draw a circle using the following:
> 
> %%%%%%%%
> \usemodule[animation]
> \setupinteraction[state=start]
> \startuseMPgraphic{Circles}{s}
> numeric sn, L, N;
> path p, q;
> p := fullcircle scaled 72;
> L:=length p;
> N:=20;
> sn:= \MPvar{s};
> q := subpath (0, sn/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;
> \stopuseMPgraphic
> \starttext
> \startanimation
> \dorecurse{20}
> {\startexpanded
> %\setupMPvariables[Circles][s]
> \useMPgraphic{Circles}{s=\recurselevel}
> \stopexpanded}
> \stopanimation
> \stoptext
> %%%%%%%%%%
> 
> However, it just draw 20 figures instead of making an animation.
> 
> Would you please tell me what is wrong in the above code?

You have to put each meatiest graphic into a frame, there are three ways to create a frame.

1. Use braces around the frame

\startanimation
  {First frame}
  {Second frame}
  {Third frame}
\stopanimation

This method doesn’t work in your case where you use \dorecurse to create the graphics.


2. Use the \frame command.

\startanimation
  \frame{First frame}
  \frame{Second frame}
  \frame{Third frame}
\stopanimation

In this case the \frame command is used store the content for each frame, this can be used
when you create all frames with a loop like in your case, e.g.

\dorecurse{10}{\expanded{\frame{\useMPPgraphic{…}{var=\recurselevel}}}}


3. Use the \startframe environment.

\startanimation
  \startframe First frame \stopframe
  \startframe Second frame \stopframe
  \startframe Third frame \stopframe
\stopaniamtion

This is the same as the second method except that you use star/stop delimiters
for each frame content instead of putting it into a argument.

Wolfgang
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Re: \startanimation and \dorecurse

[Jeong Dal]

Dear Wolfgang,

According to your advice, I am able to make a working example as following.

\usemodule[animation]
\setupinteraction[state=start]

\startuseMPgraphic{Circles}{s}
numeric sn, L, N;
path p, q;
p := fullcircle scaled 72;
L:=length p;
N:=20;
sn := \MPvar{s};

q := subpath (0, sn/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;
\stopuseMPgraphic

\starttext

\startanimation[menu=yes, menucolor=blue, framerate=5]
\dorecurse{20}
{\expanded{\frame{
\useMPgraphic{Circles}{s=\recurselevel}}}}
\stopanimation

\stoptext


One more question.

In metafun document, there is a command \setupMPvariables before \startuseMPgraphic. But we don’t use it in this example. 
Hence I think that it is not necessary always. Is there any case in which we have set the MPvariables?

Thank you.

Best regards,

Dalyoung
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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