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/First « //uniformdeviate(1) - 0.5// » could be modified to « //uniformdeviate(0.5)//»./ / / /To add noise, you can use the randomized function of Metafun. For exemple, you can write:/ / / /draw pp randomized 1cm ;/ / / That's true Fabrice but in this use case I wanted a random number between -0.5 and +0.5, and I wasn't sure I would get that with randomized. Thanks again Keith McKay/ / On 26/11/2020 17:20, Fabrice L wrote:
Keith,
Le 26 nov. 2020 à 12:12, Keith McKay
mailto:mckaymeister@gmail.com> a écrit : Thanks Fabrice and Hans.
I now see I can simplify some lines of the code:
pp := ((xpart a[i])/cf*cm, (ypart a[i])/cf*cm); now becomes pp:= a[i];
and
pp := pp --- ((xpart a[i+1]/cf)*cm, (ypart a[i+1])/cf*cm); now becomes pp := pp --- a[i +1] ;
However I still have the problem in the calculation of xcoord and ycoord which are used in the creation of path pp: for squig = 1 step 1 until 15: xcoord := uniformdeviate(1) - 0.5 + (xpart a[i]/cf); ycoord := uniformdeviate(1) - 0.5+ (ypart a[i]/cf); pp := pp .. {curl 100}(xcoord*cm, ycoord*cm); endfor; I'm adding a small random amount to the x and ypart of the pair a[i] to produce a path that is like a squiggle (gribouiller in French, according to Google). I have to use cf to convert to the x and yparts to centimeters since they seem to loose the centimeter units on separation. I can't see anyway round this, or am I missing something? Thanks Keith McKay
First « uniformdeviate(1) - 0.5 » could be modified to « uniformdeviate(0.5)».
To add noise, you can use the randomized function of Metafun. For exemple, you can write:
draw pp randomized 1cm ;
Fabrice.
On 26/11/2020 15:19, Fabrice L wrote:
Hi keith,
Le 26 nov. 2020 à 10:09, Keith McKay
mailto:mckaymeister@gmail.com> a écrit : Hi,
I have been using xpart and ypart to extract these values from pairs of points in a path but I wasn't getting the correct result. I was expecting:
pair (2cm, 11cm) to give xpart 2 and ypart 11
However I was getting:
pair (2cm, 11cm) -> xpart 56.6929 and ypart 311.8096
After much head scratching and reading the MetaPost and MetaFun manuals, I realised that the units of xpart or ypart are in Postcript points or Big Points (bp), and 1 bp is 1/72 of an inch, and thus to get the values of xpart or ypart in cm I would have to use a correction factor. I had made the assumption that since the x and ypart in the pair was in cm that the result would be in cm, but I see now that this is not the case. Will I have to continue doing this or is there some magic within MetaFun which takes account of the units in a pair and outputs the result of x and ypart in the same units?
The MWE belows shows what I have been doing.
Thanks
Keith McKay
%%% MWE %%% \setuppapersize [A5, landscape][A4, portrait] \usecolors[crayola] \starttext \startMPpage StartPage; width := PaperWidth ; height := PaperHeight ; unit := cm ; numeric squig; pair a[]; a0 = (2cm,11cm); a1 = (4cm,10cm); a2 = (6cm,9cm); a3 = (8cm,8cm); show xpart a[0], ypart a[0]; %Example of result from x and ypart before applying correction factor (cf) % cf := 72/2.54; %Converts points/in to points/cm% path pp; for i = 0 step 1 until 3: pp := ((xpart a[i])/cf*cm, (ypart a[i])/cf*cm); for squig = 1 step 1 until 15: xcoord := uniformdeviate(1) - 0.5 + (xpart a[i]/cf); ycoord := uniformdeviate(1) - 0.5+ (ypart a[i]/cf); pp := pp .. {curl 100}(xcoord*cm, ycoord*cm); endfor; pp := pp --- cycle; if i < 3 : pp := pp --- ((xpart a[i+1]/cf)*cm, (ypart a[i+1])/cf*cm); fi; f :=((1.4 - 0.6) * uniformdeviate(1)) + 0.8; % Factor to lighten/darken colour % draw pp withpen pencircle xscaled 0.5mm yscaled .1mm rotated 45 withcolor (f[white,\MPcolor{BurntSienna}]); endfor; StopPage; \stopMPpage \stoptext %%%%%%%%%%%%%%
MetaPost (MetaFun) is taking care of everything regarding units. As you ave discovered, everything is translated to a unique internal dimension. So you can write:
a := (1cm,2in) ;
with no problem. The « cm » and « in » parts of the expression will become numbers to translate this number on the right unit. Fabrice.
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