# [NTG-context] Metfun macro for triangle

Stefan Müller warrence.stm at gmx.de
Thu Mar 24 11:29:53 CET 2011

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On 24.03.2011 10:57, Otared Kavian wrote:
> Hi Stefan,
>
> Thanks for the quick answer and solution!
> Your solution works perfectly in mkiv; however typesetting with mkii results in
> 	! Undefined control sequence.
> 	l.3 \startMPdefinitions
> Is there a solution with mkii?

Then just drop the MPdefinitions section and put the complete vardef
before your normal mp code in the MPcode section. That should work, I think.

> May I ask one more question?
> In the macro you wrote
> 		Triangle((0cm,0cm), (5cm,0cm), 8cm, 6cm)
> one has to specify the double of the length of each side (because a unit circle in MetaPost is a circle having diameter one). Would it be possible to change slightly the lines

Now that's strange... But I see what you mean. I didn't notice.

> 		p := fullcircle scaled la shifted za ;
> 		q := fullcircle scaled lb shifted zb ;
> so that la and lb are replaced with their doubled values? I tried
> 		p := fullcircle scaled 2*la shifted za ;

Yeah, you need parentheses here, because otherwise Metapost tries to
scale by 2 and then doesn't know how to multiply the result (the path
"fullcircle scaled 2") with "la".

p := fullcircle scaled (2 * la) shifted za ;
q := fullcircle scaled (2 * lb) shifted zb ;

> but this does not work.
>
> Thanks for your attention: OK

np, Stefan.

> On 24 mars 2011, at 10:29, Stefan Müller wrote:
>
>> Hi,
>>
>>
>> \startMPdefinitions
>> 	vardef Triangle(expr za, zb, la, lb) =
>> 		path p, q ;
>> 		pair zc ;
>> 		pickup pencircle scaled 2mm ;
>> 		drawdot za ;
>> 		drawdot zb ;
>> 		p := fullcircle scaled la shifted za ;
>> 		q := fullcircle scaled lb shifted zb ;
>> 		zc = p intersectionpoint q ;
>> 		drawdot zc ;
>> 		pickup pencircle scaled 1mm ;
>> 		za--zb--zc--cycle
>> 	enddef;
>> \stopMPdefinitions
>>
>> \starttext
>> \startMPcode
>> 	draw Triangle((0cm,0cm), (5cm,0cm), 8cm, 6cm) withcolor blue ;
>> \stopMPcode
>> \stoptext
>>
>> Stefan
>>
>> On 24.03.2011 09:59, Otared Kavian wrote:
>>> Hi all,
>>>
>>> I have a document in which I must draw several triangles for which two summits, say z0, z1, and the length of the two other sides are known, so that the third summit, say z2, is completly determined.
>>> In order to draw one triangle the following works fine:
>>>
>>> \setupcolors[state=start]
>>> \starttext
>>> \startMPcode
>>> 	z0 = (0cm,0cm) ;
>>> 	z1 = (5cm,0cm) ;
>>> 	path p, q ;
>>> 	pickup pencircle scaled 2mm ;
>>> 	drawdot z0 ;
>>> 	drawdot z1 ;
>>> 	p := halfcircle scaled 8 cm ; % twice the length of the second side at z0
>>> 	p := p shifted z0 ;
>>> 	q := halfcircle scaled 6 cm ;  % twice the length of the second side at z1
>>> 	q := q shifted z1  ;
>>> 	z2 = p intersectionpoint q ;
>>> 	drawdot z2 ;
>>> 	pickup pencircle scaled 1mm ;
>>> 	draw z0--z1--z2--cycle withcolor blue ;
>>> \stopMPcode
>>> \stoptext
>>>
>>> However I would like to have a macro, for instance named Triangle, which accepts four arguments z0,z1, length_1, length_2, so that in a MetaPost code i can use
>>> 	draw Triangle(z0,z1, 4, 3) withcolor blue ;
>>> in order to draw the above triangle.
>>> Has anyone any idea about how to do this?
>>>
>>> ___________________________________________________________________________________
>>> If your question is of interest to others as well, please add an entry to the Wiki!
>>>
>>> maillist : ntg-context at ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
>>> webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
>>> archive  : http://foundry.supelec.fr/projects/contextrev/
>>> wiki     : http://contextgarden.net
>>> ___________________________________________________________________________________
>>>
>> ___________________________________________________________________________________
>> If your question is of interest to others as well, please add an entry to the Wiki!
>>
>> maillist : ntg-context at ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
>> webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
>> archive  : http://foundry.supelec.fr/projects/contextrev/
>> wiki     : http://contextgarden.net
>> ___________________________________________________________________________________
>
> %%%%%%%%%%%%%%%%%%
> Otared Kavian
> Département de Mathématiques
> Université de Versailles Saint-Quentin
> Bâtiment Fermat
> 45 avenue des Etats Unis
> 78035 Versailles cedex
>
> Téléphone: +33 1 39 25 46 42
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> Secrétariat: +33 1 39 25 46 46
>
> e-mail: Otared.Kavian at math.uvsq.fr
>
>
>
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
>
> maillist : ntg-context at ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive  : http://foundry.supelec.fr/projects/contextrev/
> wiki     : http://contextgarden.net
> ___________________________________________________________________________________
>
```