Re: metapost spiral

Hi,

The secret is in dir that takes an angle and outputs a vector pointing
in the corresponding direction. When t = 7 for example

  .. 1/12 t * dir 16t

will equal

.. 1/12 * 7 * (cosd(16*7),sind(16*7))

/Mikael

On Mon, 30 Mar 2026 at 12:56, Hraban Ramm <[email protected]> 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?
>
> 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 randomize the points a bit to make it look hand-drawn.
>
> Hraban
>
>
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