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%NAME: texpictex.tex
% texpictex.tex -- The following macros over-ride certain definitions in the
% PiCTeX macro package. The net effect is that line-drawing is done using
% the \special's used by texpic (tpic). Several DVI printers understand
% and handle these specials.
%
% Currently, only straight lines are translated. Recently, I added a
% clipping routine to clip to the bounding box.
%
% If people extend this to included elliptic circles and quadratics,
% please forward the extensions to me (quads are used in the \arrow
% macro, making them very slow).
%
% Dirk Grunwald
% Univ. of Illinois
% grunwald@m.cs.uiuc.edu
%
\def\makebangletter{\catcode`\!=11\relax}
\def\makebangother{\catcode`\!=12\relax}
%
\makebangletter
%
% The units that texpic deals in. You should define it this way instead
% of simply saying ``0.001in'' because the difference in resolution
% actually makes a big difference
%
\newdimen\!tpu
\!tpu=1in
\divide\!tpu by 1000
%%%
%% \!maptpus -- map a PiCTeX dimension to a TeXPiC dimension
%% using the \!tpu conversion factor.
%%
%% uses: dimen0
%%
\def\!maptpus#1#2 {\dimen0=#1\divide \dimen0 by \!tpu #2=\dimen0}
%
% ** \setplotsymbol ({PLOTSYMBOL} [ ] < , >)
% ** Save PLOTSYMBOL away in an hbox for use with curve plotting routines
% ** See Subsection 5.2 of the manual.
\def\setplotsymbol(#1#2){%
\!setputobject{#1}{#2}
\setbox\!plotsymbol=\box\!putobject%
\!plotsymbolxshift=\!xshift
\!plotsymbolyshift=\!yshift
%
% Additions: compute size of dot, convert to TPUs and issue a pensize
%
\!dimenB=\wd\!plotsymbol
\!dimenC=\ht\!plotsymbol
\advance\!dimenC by \dp\!plotsymbol
\ifdim\!dimenB<\!dimenC \!dimenF=\!dimenC \else \!dimenF=\!dimenB\fi
\!maptpus{\!dimenF}{\!countC}
\special{pn \the\!countC}
\ignorespaces}
\setplotsymbol({\fiverm .})% ** initialize plotsymbol
% ** The following routine is used to draw a "solid" line between (xS,yS)
% ** and (xE,yE). Points are spaced nearly every \plotsymbolspacing length
% ** along the line.
%
% Note: this is a replacement for PicTeX \!linearsolid.
% If line clipping is enabled, the line to be drawn is
% clipped using \!clipline. If there's anything left
% to draw after clipping, it's drawn. If clipping is off,
% the line is simply drawn. In either case, line drawing
% is done by \!texpicline.
%
\def\!linearsolid{%
\let\!nextLinearAct=\!texpicline
\expandafter\ifx \!initinboundscheck \relax
\else \!clipline \if!InBounds \else \let\!nextLinearAct=\relax \fi \fi%
\!nextLinearAct%
}
%
% Texpic has increasing origin in the upper left corner, while
% pictex has origin in bottom left corner. Ergo, we flip the signs
% for y-coordinates.
%
\def\!texpicline{%
\advance\!xS by -\!xorigin
\advance\!xE by -\!xorigin
\advance\!yS by -\!yorigin
\advance\!yE by -\!yorigin
\!maptpus{\!xS}{\!countC} \!maptpus{\!yS}{\!countD} \!countD=-\!countD%
\special{pa \the\!countC \space \the\!countD}%
\!maptpus{\!xE}{\!countC} \!maptpus{\!yE}{\!countD} \!countD=-\!countD%
\special{pa \the\!countC \space \the\!countD}\special{fp}%
\ignorespaces}
%
%%%
% Code to support line clipping
%
% Line clipping routine. Clips to bounding box specified
% by (!checkleft, !checkbot) and (!checkright, !checktop).
% Note that this box is only defined if \initboundscheckon
% has been called.
%
% The clipping algorithm was published in ACM TOG Vol 3 No 1
% by people at Berkeley, but I've forgotten the complete reference.
% This was translated from a version I wrote in C.
%
%%
% After calling \!cliplines, !InBounds tells you if the line contains
% any points within the clipping window.
%
\newif\if!InBounds
%
%%
% \!clipt -- this corresponds to the routine by the same name
% in the published algorithm.
%
% Dimens used are descibed below. All are grouped and know that
% PiCTeX doesn't use dimen0..9. Variable names are taken from
% the TOG article. The junk on the r.h.s. is indenting information
%
% Globals: dimen8 corresponds to t0
% dimen9 corresponds to t1
%
% clipt dimen0 corresponds to p
% dimen1 corresponds to q
% dimen2 corresponds to r
%
% !fastclip Uses bounding boxes
%
% !clipline passes dimen3 to clipt as p
% passes dimen4 to clipt as q
% uses dimen0, dimen2
%
%
\def\!clipt#1#2{%
\dimen0=#1 \relax \dimen1=#2 \relax
\ifdim \dimen0 < \!zpt% >0
\!divide{\dimen1}{\dimen0}{\dimen2}%
\ifdim \dimen2 > \dimen9% >1
\global\!InBoundsfalse
\else% =1
\ifdim \dimen2 > \dimen8 \dimen8=\dimen2 \fi
\fi% <1
\else \ifdim \dimen0 > \!zpt% =0>1
\!divide{\dimen1}{\dimen0}{\dimen2}%
\ifdim \dimen2 < \dimen8% >2
\global\!InBoundsfalse
\else% =2
\ifdim \dimen2 < \dimen9 \dimen9=\dimen2 \fi
\fi% <2
\else% =1
\ifdim \dimen1 < \!zpt \global\!InBoundsfalse \fi
\fi% <1
\fi% <0
}
%
% fastclipcheck
%
\def\!fastclip#1#2{%
\ifdim #1<\!checkleft \global\!InBoundsfalse \else
\ifdim #1>\!checkright \global\!InBoundsfalse \else
\ifdim #2<\!checkbot \global\!InBoundsfalse \else
\ifdim #2>\!checktop \global\!InBoundsfalse \else
\fi
\fi
\fi
\fi}
%
% clipline - clip a line to the current bounding box.
% assumes line is in (!xS, !yS) and extends to (!xE,!yE) and that
% \!xdiff and \!ydiff has been set up. This is normally done
% in \!lstart.
%
% \!clipline first checks to see if the start & end points are
% conainted in the clipping box. If the simple compare works,
% then no clipping is done, else \!doclip is called to
% do the actually clipping computations.
%
\def\!clipline{%
\!!initinboundscheck
\!InBoundstrue
\!fastclip{\!xS}{\!yS}%
\!fastclip{\!xE}{\!yE}%
\if!InBounds\else\!doclip\fi}
%
\def\!doclip{%
\begingroup%
\global\!InBoundstrue%
\dimen8=0pt
\dimen9=1pt
%
\dimen3=-\!xdiff
\dimen4=\!xS \advance\dimen4 by -\!checkleft% fromX-minX
\!clipt{\dimen3}{\dimen4}%
%
\if!InBounds% 0
\dimen3=\!xdiff
\dimen4=\!checkright \advance\dimen4 by -\!xS% maxX - fromX
\!clipt{\dimen3}{\dimen4}%
%
\if!InBounds% 1
%
\dimen3=-\!ydiff
\dimen4=\!yS \advance\dimen4 by -\!checkbot% fromY-minY
\!clipt{\dimen3}{\dimen4}%
%
\if!InBounds% 2
%
\dimen3=\!ydiff
\dimen4=\!checktop \advance\dimen4 by -\!yS% maxY-fromY
\!clipt{\dimen3}{\dimen4}%
%
\if!InBounds% 3
\dimen0=1pt
%
% The following \if's truncate the line based on the solution
% to the parametric solution to the bounding box.
%
% Note that we don't have a \!multiply, the equivilent to \!divide.
% The code below compute X * Y as (x / ( 1/ Y)), which is far
% from optimal.
%
\ifdim\dimen9 < \dimen0% 4
\!divide{\dimen0}{\dimen9}{\dimen2}%
%
\dimen3=\!xdiff \!divide{\dimen3}{\dimen2}{\dimen4}%
\global\!xE=\dimen4 \global\advance\!xE by \!xS
%
\dimen3=\!ydiff \!divide{\dimen3}{\dimen2}{\dimen4}%
\global\!yE=\dimen4 \global\advance\!yE by \!yS
\fi% 4
\ifdim\dimen8 > \!zpt% 4
\!divide{\dimen0}{\dimen8}{\dimen2}%
%
\dimen3=\!xdiff \!divide{\dimen3}{\dimen2}{\dimen4}%
\global\advance\!xS by \dimen4
%
\dimen3=\!ydiff \!divide{\dimen3}{\dimen2}{\dimen4}%
\global\advance\!yS by \dimen4
\fi% 4
\fi% 3
\fi% 2
\fi% 1
\fi% 0
\endgroup}
%
\makebangother
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