An example of dmmlib

This is a simple example of how I create diagrams in postscript. It makes heavy use of dmmlib, my personal postscript library, as well as some ad-hoc functions. A certain amount of existing postscript knowledge is helpful to understand it but if you know that it's a stack-based language for drawing text and images on a page, and that % is the comment marker and that { } creates a block, you can probably make sense of it.

The image is meaningless, created when "doodling" in ps for fun.

%!
(dmmlib/base.ps) run
(dmmlib/lines.ps) run
%
% I have defined "circle" and "spcircle" as taking the arguments x y rad.
% This takes that plus one argument, so that tcircle and hcircle below
% can provide n and then match the signature of circle.
%
% arg = exch def. Handy way to pull arguments off the stack.
% I've started tucking the arguments to functions and for-loops here.
/ncircle { /n arg /rad arg /y arg /x arg
    % My spcircle has thick points at 0 and 180.  For the orientation and 
    % symmetry of this design, I wanted a thick point at 90 and 3 or 6
    % points total.
    x y translate
    % n block circrepeat = repeat with a 360/n rotate after each block.
    % Everything happens in the current reference frame and rotates back
    % around, so I can add to the current path and then closepath to make
    % symmetrical shapes and such.
    n {
        % sparc is a drop-in replacement for arc that does its own spline
        % calculation, which matters when using cstroke.
        % The built-in arc makes a new spline every 90 degrees.
        0 0 rad 90 dup 360 n div add sparc
    } circrepeat
    closepath
    x neg y neg translate
} def
/tcircle { 3 ncircle } def
/hcircle { 6 ncircle } def
%
% cstroke is a changeable alias to brushystroke, defined in lines.ps.
% brushystroke is thick along the path where a new spline or line
% starts or ends.
% I'm defining hstroke here as a tiny replacement for cstroke to set
% a hue based on an angle to make it easier to see what each section does.
/hstroke {
    360 div 1 0.7 sethsbcolor cstroke 0 setgray
} def

/HexaSomething {
    gsave
        % I like using powers of 2 for line thickness and 0.03125 is a pain.
        32 recip setlinewidth
        0 0 0.5 tcircle 0 hstroke
        0 0 1 tcircle 30 hstroke 
        % Using circrepeat provides automatic triangular rotational symmetry.
        3 {
            gsave
            0 -1 translate
                0 0 1 hcircle 60 hstroke 
            % hmirror - run the block with and without a horizontal flip.
                % hmirror _does_ act inside a gsave block.
                % there is also a vmirror defined.
                { 0.5 -0.5 goto 0.5 -1.25 goto 90 hstroke } hmirror 
            grestore
        } circrepeat
        % I actually intended to make this a rounded hexagon but got
        % the rotation direction wrong (-3 {foo} circrepeat would have worked)
        % and I liked this accident better.
        3 { 0 -1 1.5 -60 -120 arcn } circrepeat
        closepath 120 hstroke 
        3 {
            0 1 1.5 60 120 arc
            0 1 goto
            closepath
            150 hstroke 
            0 2 0.5 tcircle 180 hstroke 
        } circrepeat
        6 { 0 2 goto } circrepeat closepath 210 hstroke 
        %
        % dot is just a filled circle that's 3 times as thick as the current
        % line width, which I've found to harmonize well.
        6 { 2.250 0 dot } circrepeat
        6 { 0 2.5 goto 0 2.75 goto 240 hstroke } circrepeat 
        0 0 2.75 hcircle 270 hstroke 
        0 0 3 hcircle 300 hstroke 
    grestore
} def
%%EndProlog
% I've defined "softscale" to scale by the given number in both dimensions,
% and to divide the current line width by the same amount.
% I usually work at one unit per inch, and start in the center of the page.
72 softscale
4.25 5.5 translate
% for the printed version I want this to fill up more of the page.
1.25 softscale
HexaSomething
showpage

hexasomething.ps
hexasomething.pdf