vlasakm
commented
2 months ago Hello!
optex-minim in this repository is more or less obsolete - I should maybe archive the repository. It is not needed at all, as it has been integrated into OpTeX itself - i.e. there are minim .opm files in https://github.com/olsak/OpTeX/tree/master/optex/pkg. I hope you are using that! Because of that I think it would be best to discus things there, as the any potential change needs to happen there.
\setHEXcolor
Actually I don't know that one. Where does it come from?
Anyways, unfortunately I wouldn't even call myself a Metapost novice, since I have hardly used it (funnily enough, since I integrated it with optex through minim), but I think I can fill some details for you.
My impression from the Metapost manual and a tugboat article is, that withcolor expects to be followed by a color expression, which in turn is a "normal metapost expression". This is kind of subtle, because there is a trick - colors in metapost are essentially triplets (in case of rgb colors, i.e. (R, G, B) where R G and B are numbers between 0 and 1), quadruplets (n case of cmyk colors, i.e. (C, M, Y, K) where C M Y and K are numbers between 0 and 1) or plain numbers (in n case of grey, i.e. G where G is a number between 0 and 1).
So either of this rows is a basic metapost expression, that may be interpreted as a color:
1 % black
(0,0,0) % rgb black
(1,0,0,0) % cyanIn fact I vaguely remember, that since Metapost has just pairs for 2D coordinates, people abuse RGB colors for 3D coordinates, since they are essentially triplets built into Metapost. And it seems that Metapost really handles colors specially only after it has been instructed to handle a triplet or quadruplet or number as a color - only then it actually "clamps" the components to the range 0 - 1. But maybe there are more details that I haven't yet come by.
With these essentially normal tuples or number we can form expressions, just like for pairs or ordinary numbers:
230/255 % light grey
(1,0,0) + (0,1,0) % yellow
.8 [(1,0,0), (0,0,1)] % purple, closer to blue than redI.e. what works for points works for mixing colors as well. Even linear equations with variables. But since I am no Metapost expert, I restrained myself to these, since these seem good for basic color mixing.
Of course it would be a bit inconvenient to only use raw numbers everywhere, so Metapost defines this:
% color constants
color black, white, red, green, blue, background;
black = (0,0,0);
white = (1,1,1);
red = (1,0,0);
green = (0,1,0);
blue = (0,0,1);
background = white; % The user can reset thisSo it seems that these "names" are not that special, and defining new ones in Metapost is not a problem.
Our problem is then how to make something defined in OpTeX as:
\def \CornerDarkGreen {\setrgbcolor{0.655 0.741 0.690}}expand in Metapost to:
(0.655, 0.741, 0.690)This is just a matter of separaating the numbers by whitespace, anad inserting commas between them. Minim conveniently recently introduced a way to add definitions before and after each \directmetapost with \everymp. So then I think we can do this:
\fontfam[lm]
\load[minim-mp]
\_let\_optex_rgb=\_setrgbcolor
\_let\_optex_cmyk=\_setcmykcolor
\_let\_optex_grey=\_setgreycolor
\_def\_mp_rgb #1 #2 #3 ;{(#1, #2, #3)\_space}
\_def\_mp_cmyk #1 #2 #3 #4 ;{(#1, #2, #3, #4)\_space}
\_def\_mp_grey #1 ;{#1\_space}
\expandafter\toksapp\everymp0{pre}{tex}{
\_def\_setrgbcolor#1{\_mp_rgb #1 ;}%
\_def\_setcmykcolor#1{\_mp_cmyk #1 ;}%
\_def\_setgreycolor#1{\_mp_grey #1 ;}%
}
\expandafter\toksapp\everymp0{post}{tex}{
\_let\_setrgbcolor=\_optex_rgb
\_let\_setcmykcolor=\_optex_cmyk
\_let\_setgreycolor=\_optex_grey
}
{\Red before in red}
\directmetapost{
beginfig(1)
draw fullcircle scaled 10mm shifted (0mm, 0) withcolor \Green;
draw fullcircle scaled 20mm shifted (15mm,0) withcolor .1\Green;
draw fullcircle scaled 5mm shifted (30mm,0) withcolor .8[\Red,\Blue];
endfig;
}
{\Blue after in blue}
\byeI set \_setrgbcolor etc. to my definitions before \directmetapost through the pre hook of \everymp, then because \directmetapost doesn't seem to be a group, I need to revert these definitons in the post hook (both are "tex" and both are apply to instance 0, which is special instance number meaning all instances. The reparsing is relatively straightforward, though I am not sure whether it is better or not to include a \space after the colors.
I can then use OpTeX colors inside \directmetapost, but after \directmetapost the colors revert to their original meaning of "set TeX color", instead of "expand to text that metapost understands as color".
Unfortunately, mixing colors has some subtle problems. E.g. the following fails:
draw fullcircle scaled 20mm shifted (55mm,0) withcolor .1[\White,\Red];This is because I am trying to do an arithmetic on white (which in OpTeX is defined as grey color) and red (which in OpTeX is defined as CMYK color), and Metapost doesn't know how to do arithmetic on CMYK and number:
Not implemented: (cmykcolor)-(known numeric).Also, metapost definitions like white are mostly based on RGB (and RGB is the default color space), while in OpTeX it is CMYK (and grey for white / black), so mixing them is not possible out of the box. Use of \onlyrgb would in theory help, but this breaks, since it redefines \_setcmykcolor - a change my macros have no idea about.
There is probably a better solution for handling colors, so I will probably post an issue to the OpTeX repository asking for feedback, and possibilities on what to do with colors.
By the way, this works:
draw fullcircle scaled 20mm shifted (55mm,0) withcolor .625red + .8blue;just as well as this:
\def\mycolor{.625red + .1blue}
[...]
draw fullcircle scaled 20mm shifted (55mm,0) withcolor \mycolor;Metapost sees only the first text in both cases. The macro \mycolor gets expanded to .625red + .1blue before Metapost even runs. The syntax \def\mycolor{.625red + .1blue} is "primitive" (i.e. most basic way on which e.g. \newcommand in LaTeX is built upon), which allows to define a macro. It means that "\mycolor should from now on expand to .625red + .1blue. The brackets ({, }) are just delimiters that designate start and end of what is should be the meaning of the macro. Because you could also have:
\def \mycolor { .625red + .1blue }Where the spaces sometimes are and sometimes aren't significant - the good old weird TeX.
And yes indeed, you are right that this deserves a case in examples after I figure out a good way to implement usage of OpTeX colors in minim Metapost - the above is just a rough idea (though you can probably use it in the mean time, since from above you know the limitations).
reuleaux
Hi, thanks for creating optex-minim - I am doing my first baby steps with optex + minim (your optex-minim i.e.) + metapost (while also looking at the context docs) etc. - having some experience with latex/context, but less so with plain tex - i.e. I am learning all these at the same time - so bear with me, please.
I can (partly) set the background of some pages in optex with metapost in color, like so:
i.e. I want to use slightly more complicated colors - than the usual red/green/blue...
Now, ideally I would use my optex color definitions - there are various ways to do them: (with
\setrgbcolor,\setHEXcoloretc. - you know the optex docs)etc. - now, I am having a hard time accessing / using such definitions in metapost (and I am not sure: do I need to write a macro to do so? Can I directly access optex definitions within minim - the minim docs seem to suggest so: there is a mention of
\mpcolor- well for latex, not optex - and then: a (very general) section "running tex from within metapost" - but there are not really any examples given.note that this works (but sets only a certain red level):
I don't really know: maybe this is general TeX knowledge - but I am not aware: where does this syntax come from:
{.625red}- and more importantly: how to use it a little more generally: this does not workmaybe I need a comma in between red and blue, maybe
+- I think I have tried everything.maybe I can just use
\mpcolor{\CornerDarkGreen}in the metapost above - I think I have tried this, without success!Maybe you could provide some hints - or ideally even add an example (to your examples directory)? Thanks!