flag.ps

%!PS-Adobe-3.0

% Texas flag.
% https://github.com/srl295/txflag.git

% Copyright © 2020 by Steven R. Loomis
%
% Licensed under the Apache License, Version 2.0 (the "License");
% you may not use this file except in compliance with the License.
% You may obtain a copy of the License at
%     http://www.apache.org/licenses/LICENSE-2.0


/in {72 mul} def
/GRAY { 0.1 setgray  } def
/BLUE { 0.25 setgray 0 0.12549019607843137 0.3568627450980392 setrgbcolor } def
/RED { 0.75 setgray 191 256 div 13 256 div 62 256 div setrgbcolor} def
/WHITE { 1.0 setgray 1 1 1 setrgbcolor } def

/height 3 in def
/width 3 2 div height mul def
/inset 1 in def

% add text

/Helvetica findfont 0.1 in scalefont setfont
3 in 0.5 in moveto
(https://github.com/srl295/txflag.git) show

% number of points
/starpt 5 def
% 0 = no depth (polygon). 1 = starfish.
% This is the multiplied against (𝜃/2) to calculate the outside angle of the star's "cut in"
/stardepth 1 def

% set this to 1 for debug or 0 for no debug
% shows the legally specified circle of reference, plus shows a polygon behind the star (in red)
/DEBUG 0 def

% Internal Defs
% blue width
/bwid width 3 div def
% half blue width
/hbwid bwid 2 div def
% half-height
/hheight height 2 div def
% white width - twice the blue width
/wwid bwid 2 mul def
% now the star
/starwidth width 3 div .75 mul def
/hstarwidth starwidth 2 div def

% interior angle of nominal polygon
/theta 360 starpt div def
% 𝜃 = 360°/starpt

% edge of nominal polygon
/ell
    starwidth 2 div
    theta 2 div sin 
  mul 2 mul def
  % lengt of each edge =
  % l = 2r × sin (𝜃/2)
  % where r = 2w

% gamma  is the "cut in" angle
/gamma theta 2 div stardepth mul def
% m is the length of the single cut-in line
/emm
    ell 2 div
    gamma cos
        mul def
DEBUG {
    gsave
        0 setgray
        gsave
            1 in height 2 mul  translate
            0.5 setlinewidth 
            0 0 moveto 1 in 0 rlineto stroke
            2 setlinewidth
            theta neg rotate
            newpath
                0 0 moveto
                    % 0 1 inch rlineto 0 .5 inch neg rlineto 
                    ell 0 rlineto 
                    % 0 1 inch rlineto 0 .5 inch neg rlineto 
            stroke
        grestore

        gsave
            4 in height 2 mul  translate
            0.5 setlinewidth 
            0 0 moveto 1 in 0 rlineto stroke
            2 setlinewidth
            gamma neg rotate
            newpath
                0 0 moveto
                    % 0 1 inch rlineto 0 .5 inch neg rlineto 
                    emm 0 rlineto 
                    % 0 1 inch rlineto 0 .5 inch neg rlineto 
            stroke
        grestore
        
    grestore
} repeat

% ----- begin

% box
inset inset translate

% /gray 0.5 0.5 0.5 setcolor def


% blue
BLUE
0 0 moveto
bwid 0 rlineto
0 height rlineto
bwid neg 0 rlineto
0 height neg rlineto
fill

% WHITE
WHITE
% .9 setgray % TEST
bwid hheight moveto
wwid 0 rlineto
0 hheight rlineto
wwid neg 0 rlineto
0 hheight neg rlineto
fill


RED
bwid 0 moveto
wwid 0 rlineto
0 hheight rlineto
wwid neg 0 rlineto
0 hheight neg rlineto
fill


% DEBUG: red polygon under the star
DEBUG {
    RED
    gsave
        bwid 2 div
        height 2 div
        translate
        % -45 rotate % DEBUG
        newpath
        0 hstarwidth moveto
        theta 2 div rotate

        starpt {
            % currentpoint starwidth 10 div 0 360 arc 
            currentpoint translate
            theta neg rotate
            ell  0  rlineto

            
            %     % 0 starwidth 2 div starwidth 10 div 0 360 arc 
            %     % stroke
            % % starwidth 5 div starwidth 2 div neg rlineto
            % 0 0 moveto 360 starpt div rotate
            % 0 starwidth 2 div lineto
        } repeat
        % closepath 
        fill
    grestore
} repeat % END debug


% the actual star!
WHITE
% GRAY
gsave
    hbwid
    hheight
    translate
    % -45 rotate % DEBUG
    newpath
    0 hstarwidth moveto
    % gamma  rotate
    % -90 rotate
    theta neg rotate
    theta 90 sub rotate
    starpt
    starpt {
        currentpoint translate
        gamma 2 div neg rotate
        emm 2.5 mul 0  rlineto % why 2.5?
        90 gamma 2 div sub rotate
        emm 2.5 mul 0 rlineto % why 2.5?
        theta 270 sub rotate
    } repeat
    % closepath 
    fill
grestore

DEBUG {
    % now the star's circle for ref
    gsave 
        GRAY
        3 setlinewidth
        [ 1 3  ] 2 setdash
        0 1 0 setrgbcolor % green
        newpath
        hbwid
        hheight
        starwidth 2 div
        0 360 arc
        stroke
    grestore
} repeat % end DEBUG

% gray (outer box)
GRAY

0 0 moveto
    0 height rlineto
    width 0 rlineto
    0 height neg rlineto
    width neg 0 rlineto
stroke



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