summaryrefslogtreecommitdiff
path: root/Master/texmf-dist/metapost/cmarrows/sgbx0015.mp
blob: 838219b64e2da254a2af5523b9b32524bd8f593c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
%% sgbx0015.mp
%% Copyright 2006 Tommy Ekola <tek@kth.se>
%
% This work may be distributed and/or modified under the conditions of
% the LaTeX Project Public License, either version 1.3 of this license
% or (at your option) any later version.  The latest version of this
% license is in http://www.latex-project.org/lppl.txt
%
% This work has the LPPL maintenance status `maintained'.  The Current
% Maintainer of this work is Tommy Ekola.  The Base Interpreter is
% MetaPost.

vardef setup_lefthalfarrow (expr source_file, cmdname) =

  scantokens ("input tgbx0000");

  scantokens ("input " & source_file);

  expandafter def scantokens cmdname expr p =
    scantokens (cmdname & "__sgbxww")(p)
  enddef;

  expandafter vardef scantokens (cmdname & "__sgbxww " & "(expr apth) " &
    "text text_ = " &

    "save math_spread, x_height, u, rule_thickness, bar, math_axis," &
    "     asc_height, eps, monospace, fudge, crisp, hair;" &
    "boolean monospace;" &

    "math_spread     :=" & decimal math_spread & ";" &
    "x_height#       :=" & decimal x_height# & ";" &
    "u#              :=" & decimal u# & ";" &
    "rule_thickness# :=" & decimal rule_thickness# & ";" &
    "bar#            :=" & decimal bar# & ";" &
    "math_axis#      :=" & decimal math_axis# & ";" &
    "asc_height#     :=" & decimal asc_height# & ";" &
    "eps             :=" & decimal eps & ";" &
    "monospace       :=" & if monospace: "true" else: "false" fi & ";" &
    "fudge           :=" & decimal fudge & ";" &
    "crisp#          :=" & decimal crisp# & ";" &
    "hair#           :=" & decimal hair# & ";")
      
    save prevpen;
    prevpen:=savepen;

    save x,y;
    numeric x[], x[]', x[]l, x[]'l, x[]r, x[]'r,
            y[], y[]', y[]l, y[]'l, y[]r, y[]'r;
    save spread, w;
    numeric spread, w;
  
    if crisp#>fudge*hair#:
      crisp#:=fudge*hair#;
    fi
    pickup if crisp#=0: nullpen else: pencircle scaled crisp# fi;

    spread = math_spread[.45x_height#, .55x_height#];
    w = 18u#;

    penpos1(rule_thickness#, 90); penpos2(rule_thickness#, 90);
    penpos3(rule_thickness#,  0); penpos4(rule_thickness#,  0);
    y0=y1=y2=math_axis#; x1-.5rule_thickness#=u#; rt x0=w-u#;
    y3-y0=y0-y4=.36asc_height#+eps;
    x3=x4=x0-4u#-eps;
    penpos5(rule_thickness#, angle(z4-z0)); z5l=z0;
    penpos6(rule_thickness#, angle(z3-z0)); z6l=z0;
    save t; numeric t; 
    save pq; path pq;    pq = z4l..{2(x0-x4),y0-y4}z6r;
    t=xpart(pq intersectiontimes ((0,y2l)--(w,y2l))); x2=xpart point t of pq;
    z9=.2[.5[z3,z4],z0];

    save mapto, n;
    vardef mapto(text t) =
      hide(numeric n; n:=0;
           numeric x,x_[],y,y_[];
           for z=t: z_[incr n]:=z; endfor;
           transform T;
           z_2 = z_1 transformed T;
           z_4 = z_3 transformed T;
           z_6 = z_5 transformed T;)
      T
    enddef;
  
    save T;   transform T;
    save tt;  numeric tt;  tt  = arctime(arclength apth - (x0-x9)) of apth;
    save ttt; numeric ttt; ttt = arctime(arclength apth - (x0-x2)) of apth;

    % Draw the arrow head

    save pp; path pp; pp := (z3l..{2(x0-x3),y0-y3}z5r);
    save pq; path pq; pq := (z3r..{2(x0-x3),y0-y3}z5l);

    save halfarrowhead, pa;
    vardef halfarrowhead(expr T, s) =
      (z0--(x0,y2l)--z2l--z2r
         ..subpath(t,s) of pp
         --subpath(xpart( pq intersectiontimes
	             (point s of pp -- point s of pp +(2rule_thickness#,0))),
	           length (z3r..{2(x0-x3),y0-y3}z5l)) of pq --cycle)
      transformed T
    enddef;
  
    if     arclength apth = 0:
      T:=identity shifted (point (length apth) of apth - z0);
    elseif arclength apth < x0-x3l:
      T:=identity rotatedaround(z0,angle (direction (length apth) of apth))
                  shifted (point (length apth) of apth -z0);
    else:
      T:=mapto(z0,
               point (length apth) of apth,
               z2,
               point ttt of apth,
               z9+(0,3rule_thickness#),
               point tt of apth + 3rule_thickness#*
                     (unitvector (direction tt of apth) rotated 90));

    fi

    save f,s;
    vardef f(expr s) =
      length(point s of (pp transformed T) - point tt of apth)
      < length(point 0 of pp - z9)
    enddef;

    if f(0) or (arclength apth < x0-x3l): s := 0;
    else:    s := solve f(length pp, 0);
    fi

    filldraw halfarrowhead(T,s) text_;
    
    % Draw the path

    if arclength apth > x0-x2: draw subpath(0,ttt) of apth
      withpen pencircle scaled rule_thickness# text_;
    fi

    pickup prevpen;

  enddef;

enddef;