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terryburtonterryburton
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renmatrix: Use bitmask and direction lookup table for path tracing
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‎src/renmatrix.ps.src‎

Lines changed: 107 additions & 38 deletions
Original file line numberDiff line numberDiff line change
@@ -52,6 +52,88 @@ begin
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/forward dup /backward dup /upward dup /downward dup
5353
>> readonly def
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55+
/renmatrix.left 1 def
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/renmatrix.right 2 def
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/renmatrix.up 4 def
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/renmatrix.down 8 def
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%
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% Direction lookup table indexed by 2x2 neighbourhood:
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%
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% +---+---+
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% |A=8|B=4|
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% +---*---+
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% |C=2|D=1|
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% +---+---+
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%
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/renmatrix.tracestep [
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% 0 0
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null % ?
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% 0 0
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% 0 0
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{right} % +>
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% 0|1
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% 0 0
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{down} % -+
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% 1v0
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% 0 0
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{right} % -->
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% 1 1
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% 0^1
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{up} % +-
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% 0 0
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% 0^1
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{up} % |
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% 0|1
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% 0 1 0^1
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{dir //renmatrix.right eq {down} {up} ifelse} bind % -+ or +-
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% 1v0 1 0
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% 0^1
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{up} % -+
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% 1 1
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% 1|0
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{left} % <+
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% 0 0
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% 1|0 1 0
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{dir //renmatrix.down eq {left} {right} ifelse} bind % <+ or +>
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% 0 1 0|1
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% 1|0
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{down} % |
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% 1v0
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% 1|0
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{right} % +>
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% 1 1
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% 1 1
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{left} % <--
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% 0 0
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% 1 1
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{left} % <+
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% 0|1
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% 1 1
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{down} % +-
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% 1v0
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% 1 1
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null % ?
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% 1 1
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] readonly def
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55137
/renmatrix {
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128 dict begin
@@ -155,54 +237,40 @@ begin
155237
/bwipp.renmatrixBadTextsize (extratextsize must be greater than zero and less that 25) //raiseerror exec
156238
} if
157239

158-
/xyget { pixx mul add pixs exch get} def
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/cget { pixx mul add cache exch get and} def
240+
/xyget { pixx mul add pixs exch get } def
241+
/cget { pixx mul add cache exch get and } def
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/cput { % Optimise by only storing "stem" corners
161-
dup 4 mod 0 eq { % dir is up or left
243+
dup dup //renmatrix.up eq exch //renmatrix.left eq or { % dir is up or left
162244
3 1 roll pixx mul add cache exch 2 copy get 4 -1 roll or put
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} {
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pop pop pop
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} ifelse
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} def
167249

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/abcd {
169-
4 string 0 [
170-
5 -2 roll
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pixx mul add dup
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pixs exch 2 getinterval aload pop 3 -1 roll % A B
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pixs exch pixx add 2 getinterval aload pop % C D
174-
] {3 copy 48 add put pop 1 add} forall pop
251+
pixx mul add dup 1 add % A B
252+
1 index pixx add dup 1 add % C D
253+
pixs exch get
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exch pixs exch get 2 mul add
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exch pixs exch get 4 mul add
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exch pixs exch get 8 mul add
175257
} def
176258

177-
/right {dir 1 ne {x y dir cput [x y]} if /x x 1 add def /dir 1 def} def
178-
/down {dir 2 ne {x y dir cput [x y]} if /y y 1 add def /dir 2 def} def
179-
/left {dir 4 ne {x y dir cput [x y]} if /x x 1 sub def /dir 4 def} def
180-
/up {dir 8 ne {x y dir cput [x y]} if /y y 1 sub def /dir 8 def} def
259+
/left {dir //renmatrix.left ne {x y dir cput [x y]} if /x x 1 sub def /dir //renmatrix.left def} def
260+
/right {dir //renmatrix.right ne {x y dir cput [x y]} if /x x 1 add def /dir //renmatrix.right def} def
261+
/up {dir //renmatrix.up ne {x y dir cput [x y]} if /y y 1 sub def /dir //renmatrix.up def} def
262+
/down {dir //renmatrix.down ne {x y dir cput [x y]} if /y y 1 add def /dir //renmatrix.down def} def
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182264
%
183265
% Walk the outline of a region emitting edge coordinates of the path
184266
%
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/trace {
186268
/y exch def /x exch def
187-
% dir 1:right 2:down 4:left 8:up
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/dir x 1 add y 1 add xyget 1 eq {8} {4} ifelse def
269+
/dir x 1 add y 1 add xyget 1 eq {//renmatrix.up} {//renmatrix.left} ifelse def
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/sx x def /sy y def /sdir dir def
190271

191-
% A B
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% C D
193272
mark {
194-
x y abcd
195-
1 { % Common exit
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dup dup (0001) eq exch dup (0011) eq exch (1011) eq or or {pop right exit} if
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dup dup (0010) eq exch dup (1010) eq exch (1110) eq or or {pop down exit} if
198-
dup dup (1000) eq exch dup (1100) eq exch (1101) eq or or {pop left exit} if
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dup dup (0100) eq exch dup (0101) eq exch (0111) eq or or {pop up exit} if
200-
dup (1001) eq {
201-
dir 2 eq {pop left exit} {pop right exit} ifelse
202-
} { % 0110
203-
dir 1 eq {pop down exit} {pop up exit} ifelse
204-
} ifelse
205-
} repeat
273+
//renmatrix.tracestep x y abcd get exec
206274
x sx eq y sy eq and dir sdir eq and {exit} if
207275
} loop
208276
counttomark array astore exch pop
@@ -284,16 +352,17 @@ begin
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0 1 pixx 2 sub {
285353
/i exch def
286354
/k i j abcd def
287-
k (0001) eq k (1001) eq or { % Black region stem corners
288-
8 i j cget 0 eq {
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i j trace
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} if
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} if
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k (1110) eq { % White region stem corner
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4 i j cget 0 eq {
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i j trace
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} if
355+
k 2#0001 eq % Black region stem corners:
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k 2#1001 eq or { %
357+
//renmatrix.up i j cget 0 eq { % 0 0 1 0
358+
i j trace % * and *
359+
} if % 0 1 0 1
296360
} if
361+
k 2#1110 eq { % White region stem corner:
362+
//renmatrix.left i j cget 0 eq { %
363+
i j trace % 1 1
364+
} if % *
365+
} if % 1 0
297366
} for
298367
} for
299368
] def

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