Re: metapost spiral

On 3/30/2026 12:52 PM, Hraban Ramm wrote:
> Hi,
> 
> in https://tug.ctan.org/info/drawing-with-metapost/Drawing-with-Metapost.pdf
> I found this code to draw a spiral:
> 
> path S;
> S = origin
> for t=1 upto 90:
>    .. 1/12 t * dir 16t
> endfor;
> draw S;
> 
> I understand it starts at origin and adds a number of points – but where 
> are the points (pairs)? There’s a number (distance?) and a direction 
> (angle?). Could you explain this in layman’s terms?

"dir" produces a pair

\startMPpage
path S;
S := origin for t=1 upto 90 : .. 1/12 t * dir 16t endfor ;
S := S scaled 10 ;
draw S ;
drawpoints S withcolor red ;
\stopMPpage


> If I try a different starting point than origin, the spiral still is 
> drawn around origin. I'd like to add it to another path and also 
hm, if you replace origin by (10,10) it does looks different

 > randomize the points a bit to make it look hand-drawn.

1/12 (t randomized .05t)

Hans

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                                           Hans Hagen | PRAGMA ADE
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