Re: Metapost Animation of Sine

[Fabrice L <fabrice.alpha@gmail.com>]

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Hi,

> Le 21 juill. 2021 à 10:08, Jeroen <contextntg@gmail.com> a écrit :
> 
> I use this small animation to enlarge a circle
> 
> 
> \usemodule[animation]
> \setupinteraction[state=start]
> \starttext
> \startanimation[menu=yes,framerate=10]
> \dorecurse{7}{\expanded
>   {\startframe
>     \startMPcode
>     path p;
>     numeric n, u;
>     u := 1cm;
>     n:=\recurselevel*u;
>     p := fullcircle scaled n;
>     draw p;
>     \stopMPcode
>   \stopframe}}
> \stopanimation
> \stoptext
> 
> 
> This I use to draw a sine
> 
> 
> \starttext
> \startMPcode
>   draw(-90/360*1.5cm,-0.9cm) for i = -90 upto 630: .. (i/360*1.5cm,0.9cm*(sind(i)))endfor;
> \stopMPcode
> \stoptext
> 
> 
> When I put it together to animate the sine as following, it does not entirely create the sine animation I am looking for
> 
> 
> \usemodule[animation]
> \setupinteraction[state=start]
> \starttext
> \startanimation[menu=yes,framerate=10]
> \dorecurse{7}{\expanded
>   {\startframe
>     \startMPcode
>     path p;
>     numeric n, u;
>     u := 1cm;
>     n:=\recurselevel*u;
>     p := (-90/360*1.5cm,-0.9cm) for i = -90 upto 630: .. (i/360*1.5cm,0.9cm*(sind(i))) endfor shifted (n,0);
>     draw p;
>     \stopMPcode
>     \stopframe}}
> \stopanimation
> \stoptext
> 
> 
> What better way can I create a sine animation with Metapost?
>  
> 

Here is another way to do your animation. This is doing something, but I guess not what you want. Could you describe what do you have in mind ?

\starttext
\dorecurse{7}{ % 3180
\startMPpage
	myvariable := #1 ;
	path p;
    numeric n, u;
    u := 1cm;
    n:=myvariable*u;
    p := (-90/360*1.5cm,-0.9cm) for i = -90 upto 630: .. (i/360*1.5cm,0.9cm*(sind(i))) endfor shifted (n,0);
    draw p;
\stopMPpage
}
\stoptext

Fabrice.



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