1 Locations, angles, etc.
3 Key type is a `loc', which is a named location (absolute, 2D) and
4 direction (at the location). Angles are generally positive
5 anticlockwise; bearings are angles measured from East. The origin is
12 [-]<identifier> (- means reverse the sense)
13 Quantity (length/angle)
15 Angle units: d (degrees,default) r (radians)
16 Length units: mm (default) cm m
17 Identifiers (of locs and objects) start with lc letter, then
18 alphanums and underscores
23 Defines loc P given coordinates (distances) and absolute bearing
26 Defines loc T: start at loc F, go forward L, translate right R,
27 turn left A (defaults are all 0).
29 extend F T len L [R] length L
30 extend F T upto U [R] s.t. perpendicular at T passes through U
31 extend F T ang A R subtending directionally A
32 extend F T uptoang A R s.t. direction at T is A
33 extend F T parallel U R s.t. direction at T is same as at U
34 Draws an arc or line from loc F, defining the other end as loc T.
35 If length R specified, draws an arc of radius R; R +ve curves to the
36 right; R -ve to the left.
39 Joins one existing loc, F, to another, T. F's direction points to
40 the new track; T's away - ie the added track leaves F in F's
41 direction and arrives at T in T's direction. R is the minimum curve
42 radius allowed. S selects from the available solutions, and may be
44 long prefer longer length solution
45 short prefer shorter length solution
46 right|left prefer mostly bending to the left resp. right
47 beginright|beginleft prefer first bend to the right
48 endright|endleft prefer final bend to the right
49 [!]twoarcs prefer [not] two circular arcs of equal radius
50 [!]arcline prefer [not] one line and an arc of max radius
51 [!]arcsline prefer [not] line between two arcs of min radius
52 if this doesn't resolve, will pick the shortest.
57 Defines the object or part O. Inside the definition, the commands
58 do not draw when the object is being defined. The object has its
59 own coordinate space and its own location namespace. `defpart'
60 defines a `part', which is like an object except that:
61 * showlibrary lists only parts, not objects
62 * the -e and -E command line options distinguish parts and objects
64 part N [-]O [F A] [FR AR ...]
66 Places an instance of object or part O. The loc defined inside O as
67 F (`formal parameter', F must be just <identifier>) is placed at
68 existing loc A (`actual parameter').
70 Both objects (defined with defobj) and parts (defined with defpart)
71 may be placed with either command ! Whether it's a part or an obj
72 depends on the definition, not on the use - the use is just
73 different syntaxes for the same kind of operation, and where the
74 features offered by both `part' and `obj[flip]' overlap the
75 behaviour is identical.
77 If `part N -O' or `objflip' is used, rather than `part N O' or
78 `obj', then the object is placed with object-space y coordinates
79 negated (ie, it is mirrored so that the object's North exchanges
82 For `part', each FR (`formal result') and AR (`actual result')
83 specifies that the loc FR inside O is exported into the global
84 namespace as a new loc AR. Either FR or AR may start with `-'.
85 Also, each loc L inside O is exported into the global namespace as a
86 new loc N_L (unless N_L already exists).
88 For `obj[flip]' if prefix P (syntax is that of an identifier) is
89 specified, each other loc L inside O is exported into the global
90 namespace as a new loc PL (unless PL already exists). P may be `='
91 to indicate an empty prefix (default is not to export locs).
95 -D turn on debug (level 1) } currently only debug levels are
96 -Dnnn set debug level to nnn } 0 (none) and 1 (some)
99 Turn on and off drawing of elements in groups.
100 These are abbreviations for various -E... options.
104 S rails and sleepers only aRSc
105 C centrelines only arsC
106 c swept area and ticks only Arsc
108 L label top-level locs (turns on bars for them too) LM
109 l do not label any locs l
110 bars at locs (thick lines perp to track dir'n)
111 M bars for top-level locs only Mno
112 N bars for top-level locs and those in obj's MNo
113 O bars for everything, including those inside parts MNO
114 m no bars (turns off labelling too) mnol
116 -E[ARSCLMNOarsclmno]...
117 enable (capitals) or disable (lowercase) drawing of
119 A draw track swept area, with ticks
121 S draw track sleepers
122 C draw track centrelines
124 M mark locs with a bar
125 N mark locs with a bar in objs
126 O mark locs with a bar in parts
128 -q quiet: do not print info to stderr
129 (default: prints bounding box, at the moment)
131 Default is -d0, -EaRscLMNo, not quiet.
133 Special comments in PostScript:
136 a command C with args A is read for execution in scope S
138 point L in scope S has coords X Y and angle A
139 %L bbox width W (L..R)
140 %L bbox height H (B..T)
141 bounding box, giving width W, height H, left L, right R,
142 bottom B and top T. Includes full swept area of track,
143 but only at locs (so curves which bend outside bounding
144 box don't get counted)
145 %L bbox no locs, no bbox
146 there were no locs, so there is no bounding box
147 usu because input file was just obj defns and showlibrary
150 O! when defining object or part O
151 N:T scope T but inside part (introduced with `part') N
152 O::T scope T but inside obj (introduced with `obj[flip]') O