Re: metapost spiral

Thanks for the answers, Mikael, Taco & Hans!


Am 30.03.26 um 13:30 schrieb Hans Hagen via ntg-context:
> 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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