Hi Aditya, Thank you very much ! That's great indeed, you gave me an elegant solution. One more question, in order for me to understand a little more: when defining a new dotlabel as you do, might it not conflict with the internal definitions of dotlabel in Metafun in some other place? Maybe it is safer for me to call it something like « dotshapelabel » ? Best regards and agin many thanks: Otared

On 10 Dec 2020, at 18:44, Aditya Mahajan wrote:

On Thu, 10 Dec 2020, Otared Kavian wrote:

...

Hi all,

In Metafun when representing a point I woul dlike to have some dots represented by a square (or even by another scalable symbol): for instance in the following I would like the dot at the point B to be a square:

\starttext \startMPcode draw (2cm,3cm) -- (3cm,5cm) ; dotlabel(textext("\switchtobodyfont[8pt]" & "A"), (2cm,3cm)) withpen pencircle scaled 12pt withcolor transparent("exclusion",.5,red) ;

dotlabel(textext("\switchtobodyfont[8pt]" & "B"), (3cm,5cm)) withpen pencircle scaled 12pt withcolor transparent("exclusion",.5,red) ; \stopMPcode \stoptext

I wonder whether it is possible to define something like « drawsquaredot » or « squaredotlabel » in order to do this.

dotlabel uses a pen to draw the dot, and I am not sure why it uses that rather than a path. Here is a (to me) simpler definition, where you can change the shape:

\startMPdefinitions newpath dotlabelshape;

dotlabelshape := fullcircle;

vardef dotlabel@#(expr s,z) text t_ = label@#(s,z) t_ ; fill (dotlabelshape scaled 2dotlabeldiam) shifted z t_; enddef ; \stopMPdefinitions

\starttext \startMPcode newpath p ; p := (2cm, 3cm) -- (3cm, 5cm); dotlabeldiam := 12pt;

% Default draw p; dotlabel(textext("\switchtobodyfont[8pt]" & "A"), point 0 of p) withcolor transparent("exclusion",.5,red) ;

dotlabel(textext("\switchtobodyfont[8pt]" & "B"), point 1 of p) withcolor transparent("exclusion",.5,red) ;

% Using a square "dot" p := p shifted (5cm, 0); dotlabelshape := fullsquare;

draw p; dotlabel(textext("\switchtobodyfont[8pt]" & "A"), point 0 of p) withcolor transparent("exclusion",.5,red) ;

dotlabel(textext("\switchtobodyfont[8pt]" & "B"), point 1 of p) withcolor transparent("exclusion",.5,red) ; \stopMPcode \stoptext

These types of macros are also a good candidate for the new LMTX syntax, where we can make all components configurable via a key-value interface (labeldistance etc. as well).

Aditya

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On 12/10/2020 7:04 PM, Aditya Mahajan wrote:

On Thu, 10 Dec 2020, Otared Kavian wrote:

...

Hi Aditya, Thank you very much ! That's great indeed, you gave me an elegant solution.

One more question, in order for me to understand a little more: when defining a new dotlabel as you do, might it not conflict with the internal definitions of dotlabel in Metafun in some other place? Maybe it is safer for me to call it something like « dotshapelabel » ?

In general, I agree. Redefining internal macros has the advantage that your code doesn't have to change. See, for example:

it depends a bit ... redefing dotlabel in a compatible way is kind of ok, but using/redefining \foo_bar_something_internal is a real bad idea as that is not part of the interface (okay, i know that there are macro packages out there where it's part of the concept to redefine low level stuff for styles but in context we should try to avoid it ... we should then adapt the high level interface to suport something) it also depends who does it ... i know that aditya knows the internals well enough to deal with it (one of my concerns is always that while we try to come up with efficient solutions it's easy to make things inefficient but that's not the case here ... unless of course we want to nurture the 'context is slow' meme) Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------

On Thu, 10 Dec 2020, Hans Hagen wrote:

...

dotlabel uses a pen to draw the dot, and I am not sure why it uses that rather than a path. Here is a (to me) simpler definition, where you can change the shape:

just look in the pdf ... in your case the dot is a n point path while otherwise it uses the default postscript pen (which is a dot)

Ah, that makes sense.

it surprised me that a math guru like you doesn't do this:

vardef dotlabel@#(expr s,z) text t_ = % draw textext("$\bullet$") scaled (1/2) shifted z ; % draw textext("$\blacktriangle$") scaled (1/4) shifted z ; draw textext("$\blacksquare$") scaled (1/4) shifted z ; label@#(s,z) t_ ; enddef ; \stopMPdefinitions

Ha! I know that you said this as a joke, but as someone who did try to use the old font-based picture environment in LaTeX back in the day, I would never try to use fonts for "drawing". Especially, math fonts, where every designer has a different idea of what the shape should look like. Aditya