Re: [9fans] pic

[Russ Cox <rsc@swtch.com>]

>> Otherwise, I've found that it is always worth the time to
>> program the drawings (pic macros, postscript functions,
>> metapost, whatever), because then editing them is possible.
>
> out of interest, which of these do you use yourself by preference?

I don't think I have one that I would say I prefer,
but they're all preferable to using a WYSIWYG editor
and then having to go back and change all the diagrams
in the same way.

> http://2.bp.blogspot.com/_ZnVhQ3NyEx0/S4NfiL9UgZI/AAAAAAAAAB0/mW2hZr-Ay5k/s400/gorace4.png
>
> getting those curves right can't be that easy if you're working
> out the parameters manually, and doing the collision avoidance
> programmatically can't be too easy either...

This was pic, with copy-and-paste but only around 60 lines.
It's a one-off.

.sp
.PS
.fp 5 CW LucidaSansCW83
texty=0.015
dx=0.3
dy=0.3
"\X'PS 4 setlinewidth'"
"\f5"
rx=0.015

boxwid=0.4
boxht=0.15

IP: [
	Box: box ht 3*boxht
	line from 0.333<Box.sw,Box.nw> to 0.333<Box.se,Box.ne>
	line from 0.667<Box.sw,Box.nw> to 0.667<Box.se,Box.ne>
	Ptr: circle fill rad 0.01 at 0.167<Box.n,Box.s>
	"0" at 0.5<Box.n,Box.s>
	"7" at 0.833<Box.n,Box.s>
	"\s-2\fIptr \fP\s+2" rjust at 0.833<Box.sw,Box.nw>-(rx,texty)
	"\s-2\fIoff \fP\s+2" rjust at 0.5<Box.sw,Box.nw>-(rx,texty)
	"\s-2\fIlen \fP\s+2" rjust at 0.167<Box.sw,Box.nw>-(rx,texty)
]

JP: [
	Box: box ht 3*boxht
	line from 0.333<Box.sw,Box.nw> to 0.333<Box.se,Box.ne>
	line from 0.667<Box.sw,Box.nw> to 0.667<Box.se,Box.ne>
	Ptr: circle fill rad 0.01 at 0.167<Box.n,Box.s>
	"1" at 0.5<Box.n,Box.s>
	"2" at 0.833<Box.n,Box.s>
	"\s-2\fIptr \fP\s+2" rjust at 0.833<Box.sw,Box.nw>-(rx,texty)
	"\s-2\fIoff \fP\s+2" rjust at 0.5<Box.sw,Box.nw>-(rx,texty)
	"\s-2\fIlen \fP\s+2" rjust at 0.167<Box.sw,Box.nw>-(rx,texty)
] with .n at IP.s + (0, -0.5)

I: [
	Box: box ht 2*boxht invis
	"\X'PS 0.8 0.3 0.3 setrgbcolor 20 setlinewidth'" at Box
	box ht 2*boxht at Box
	"\X'PS 0 0 0 setrgbcolor 4 setlinewidth'" at Box
	box ht 2*boxht at Box

	line from Box.w to Box.e
	"\s-2\fIbase \fP\s+2" rjust at 0.25<Box.nw,Box.sw>-(rx,texty)
	"\s-2\fIcap \fP\s+2" rjust at 0.75<Box.nw,Box.sw>-(rx,texty)
	Base: circle fill rad 0.01 at 0.25<Box.n,Box.s>
	BaseData: "[1, 2, 3, 4, 5, 6, 7]" ljust at 0.25<Box.ne,Box.se>+(dx*2/3,0)
	"7" at 0.5<Box,Box.s>-(0,texty)
	line -> from Base to BaseData.w
] with .nw at IP.ne + (0.5,-0.25)

spline -> from IP.Ptr to I.Box.nw+(-0.2,0.2) to I.Box.nw
spline -> from JP.Ptr to JP.Ptr+(0.75,0) to I.Box.nw-(0.5,0.1) to I.Box.nw

"x := []int{1,2,3,4,5,6,7}" ljust "" at IP.Box.nw
"" "[]int" ljust at IP.Box.sw

"y := x[1:3]" ljust "" at JP.Box.nw
"" "[]int" ljust at JP.Box.sw
.PE

Steve said a load of complex diagrams, though, and for that
I think it's more important to be able to go back and
fix things.  The diagrams in the regexp articles are also
pic but with macros for drawing each kind of node.

	A: [ circa(b, 0, 0, , "\v'-0.02i'\*(q8", ) box invis ht 0.15 wid 0 ]
	B: [ circa(b, 0, 0, , "\v'-0.02i'\*(q9", ) box invis ht 0.15 wid 0 ]
with .n at A.s-(0,dy)
	S: [ circ(0, "", "\v'-0.02i'\*(q6,\*(q7", "") ] at 0.5<A.w,B.w>-(dx,0)
	SS: [ circa(a,1,0,"\*(q1,", "\v'-0.05i'\*(q2, \*(q3", )
	       circa(b,1,0,,"\v'-0.02i'\*(q4,\*(q5",) ] with .e at S.w
	F: [ final(0,,"\v'-0.02i'\*(qA", ) ] at 0.5<A.e,B.e>
	start(SS)
	spline -> from S.n up (dd-r) then right (dd-r) then to A.w
	spline -> from S.s down (dd-r) then right (dd-r) then to B.w
	spline -> from B.e-(dx,0) right (dx-dd+r) then right (dd-r) then to F.s
	spline -> from A.e-(dx,0) right (dx-dd+r) then right (dd-r) then to F.n
	"\f(CWa\fP" "" at A.w-(dx/2,0)
	"\f(CWb\fP" "" at B.w-(dx/2,0)

The diagrams in this paper were all hand-written PostScript.
http://publications.csail.mit.edu/lcs/pubs/pdf/MIT-LCS-TM-650.pdf

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