20. Some Larger Examples

Here are a few larger examples, with complete source code. One of our earlier examples is generated in an instructive way using a for loop:

.PS
# Draw a demonstration up left arrow with grid box overlay
define gridarrow
{
    move right 0.1
    [
        {arrow up left $1;}
        box wid 0.5 ht 0.5 dotted with .nw at last arrow .end;
        for i = 2 to ($1 / 0.5) do
        {
            box wid 0.5 ht 0.5 dotted with .sw at last box .se;
        }
        move down from last arrow .center;
        [
            if ( $1 == boxht ) \
            then { "\fBline up left\fP" } \
            else { sprintf("\fBarrow up left %g\fP", $1) };
        ]
    ]
    move right 0.1 from last [] .e;
}
gridarrow(0.5);
gridarrow(1);
gridarrow(1.5);
gridarrow(2);
undef gridarrow
.PE

Figure 20-1: Diagonal arrows (dotted boxes show the implied 0.5-inch grid)

Here’s an example concocted to demonstrate layout of a large, multiple-part pattern:

.PS
define filter {box ht 0.25 rad 0.125}
lineht = 0.25;
Top: [
    right;
    box "\fBms\fR" "sources";
    move;
    box "\fBHTML\fR" "sources";
    move;
    box "\fBlinuxdoc-sgml\fP" "sources" wid 1.5;
    move;
    box "\fBTexinfo\fP" "sources";

    line down from 1st box .s lineht;
    A: line down;
    line down from 2nd box .s; filter "\fBhtml2ms\fP";
    B: line down;
    line down from 3rd box .s; filter "\fBformat\fP";
    C: line down;
    line down from 4th box .s; filter "\fBtexi2roff\fP";
    D: line down;
]
move down 1 from last [] .s;
Anchor: box wid 1 ht 0.75 "\fBms\fR" "intermediate" "form";
arrow from Top.A.end to Anchor.nw;
arrow from Top.B.end to 1/3 of the way between Anchor.nw and Anchor.ne;
arrow from Top.C.end to 2/3 of the way between Anchor.nw and Anchor.ne;
arrow from Top.D.end to Anchor.ne
{
    # PostScript column
    move to Anchor .sw;
    line down left then down ->;
    filter "\fBpic\fP";
    arrow;
    filter "\fBeqn\fP";
    arrow;
    filter "\fBtbl\fP";
    arrow;
    filter "\fBgroff\fP";
    arrow;
    box "PostScript";

    # HTML column
    move to Anchor .se;
    line down right then down ->;
    A: filter dotted "\fBpic2img\fP";
    arrow;
    B: filter dotted "\fBeqn2html\fP";
    arrow;
    C: filter dotted "\fBtbl2html\fP";
    arrow;
    filter "\fBms2html\fP";
    arrow;
    box "HTML";


    # Nonexistence caption
    box dashed wid 1 at B + (2,0) "These tools" "don’t yet exist";
    line chop 0 chop 0.1 dashed from last box .nw to A.e ->;
    line chop 0 chop 0.1 dashed from last box .w  to B.e ->;
    line chop 0 chop 0.1 dashed from last box .sw to C.e ->;
}
.PE

Figure 20-2: Hypothetical production flow for dual-mode publishing

Figure 20-3: Three-dimensional Boxes

Here the source code for figure 20-3:

.PS
# a three-dimensional block
#
# tblock(<width>, <height>, <text>)

define tblock { [
  box ht $2 wid $1 \
      color "gold" outlined "black" \
      xslanted 0 yslanted 0 \
      $3;
  box ht .1 wid $1 \
      color "yellow" outlined "black" \
      xslanted .1 yslanted 0 \
      with .sw at last box .nw;
  box ht $2 wid .1 \
      color "goldenrod" outlined "black" \
      xslanted 0 yslanted .1 \
      with .nw at 2nd last box .ne;
] }


tblock(1, .5, "Master" "1");
move -.1
tblock(.5, 1, "Slave");
.PE