[NTG-context] Problem with a defined colour in MetaFun

[Fabrice L]

Sorry, I was a little too enthusiastic, here here is the code :

> Le 28 avr. 2022 à 08:41, Fabrice L <fabrice.alpha at gmail.com> a écrit :
> 
> Hi Keith,
> 
>> Le 28 avr. 2022 à 06:05, Keith McKay via ntg-context <ntg-context at ntg.nl <mailto:ntg-context at ntg.nl>> a écrit :
>> 
>> Hi,
>> 
>> In the MWE below I define an rgb colour, myColor1, using random numbers for the r, g and b components. I then use it to fill a unitsquare the size of the page, which works as expected. In the loop that follows I then use the defined colour, myColor1, along with white and the variable r to create shades of myColor1 as in the MWE below. However, myColor1 is not recognised in the loop and seems to be replaced by black, although if I use a predefined colour, in this case BurntSienna from the crayola collection, it works as expected.  I have tried a number of ways to get this to work as shown in the code but without success. I would be grateful for any suggestions.
>> 
>> Best Wishes
>> 
>> Keith McKay
>> 
>> %%%%%%%%%%%%%%%%%%%%MWE%%%%%%%%%%%%%
>> \setuppapersize[A4,portrait]
>> \usecolors[crayola]
>> \starttext
>> \dorecurse{10}{
>> \startMPpage
>> StartPage;
>> \definecolor[name="myColor1", r =  uniformdeviate(1), g = uniformdeviate(1), b = uniformdeviate(1) ] ;
>> fill unitsquare xscaled PaperWidth yscaled PaperHeight withcolor  "myColor1";
>> for i =2 step 2 until 10:
>> r := i/10;
>> fill unitsquare xscaled 5cm yscaled .5cm shifted (1cm,i*cm) withcolor(r[\MPcolor{BurntSienna},white]);
>> fill unitsquare xscaled 5cm yscaled .5cm shifted (7cm,i*cm) withcolor(r[\MPcolor{myColor1}, white]);
>> fill unitsquare xscaled 5cm yscaled .5cm shifted (13cm,i*cm) withcolor(r[\MPcolor{"myColor1"}, white]);
>> %fill unitsquare xscaled 5cm yscaled .5cm shifted (13cm,i*cm) withcolor(r[myColor1 ,  white]); This line causes an error.
>> endfor;
>> StopPage;
>> \stopMPpage
>> }
>> 
>> \stoptext
>> %%%%%%%%%%%%%%%%%%%%%%%%%%%end MWE%%%%%%%%%%%
>> 
> 
> Here is a solution, with works here, defining in another way the color «  myColor »:
> 
> \setuppapersize[A4,portrait]
> \usecolors[crayola]
> \starttext
> \dorecurse{2}{
> \startMPpage
> StartPage;
> color myColor ;
> myColor := (uniformdeviate(1),uniformdeviate(1),uniformdeviate(1));
> fill unitsquare xscaled PaperWidth yscaled PaperHeight withcolor myColor;
> for i =2 step 2 until 10:
> r := i/10;
> fill unitsquare xscaled 5cm yscaled .5cm shifted (1cm,i*cm) withcolor(r[\MPcolor{BurntSienna},white]);
> fill unitsquare xscaled 5cm yscaled .5cm shifted (7cm,i*cm) withcolor(r[\MPcolor{myColor1}, white]);
> fill unitsquare xscaled 5cm yscaled .5cm shifted (13cm,i*cm) withcolor(r[\MPcolor{"myColor1"}, white]);
> %fill unitsquare xscaled 5cm yscaled .5cm shifted (13cm,i*cm) withcolor(r[myColor1 ,  white]); This line causes an error.
> endfor;
> StopPage;
> \stopMPpage
> }
> 
> \stoptext

I forgot to remove « myColor1 » from the others parts of the code. 
\setuppapersize[A4,portrait]
\usecolors[crayola]
\starttext
\dorecurse{10}{
\startMPpage
StartPage;
color myColor ;
myColor := (uniformdeviate(1),uniformdeviate(1),uniformdeviate(1));
fill unitsquare xscaled PaperWidth yscaled PaperHeight withcolor myColor;
for i =2 step 2 until 10:
r := i/10;
fill unitsquare xscaled 5cm yscaled .5cm shifted (1cm,i*cm) withcolor(r[\MPcolor{BurntSienna},white]);
fill unitsquare xscaled 5cm yscaled .5cm shifted (7cm,i*cm) withcolor(r[myColor, white]);
fill unitsquare xscaled 5cm yscaled .5cm shifted (13cm,i*cm) withcolor(r[myColor, white]);
%fill unitsquare xscaled 5cm yscaled .5cm shifted (13cm,i*cm) withcolor(r[myColor1 ,  white]); This line causes an error.
endfor;
StopPage;
\stopMPpage
}

\stoptext


> 
> Fabrice.
>> 
>>     
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