Locations, angles, etc. Key type is a `loc', which is a named location (absolute, 2D) and direction (at the location). Angles are generally positive anticlockwise; bearings are angles measured from East. The origin is at the South-West. Syntaxes New location Existing location [-] (- means reverse the sense) Quantity (length/angle) [] Angle units: d (degrees,default) r (radians) Length units: mm (default) cm m Identifiers (of locs and objects) start with lc letter, then alphanums and underscores Commands abs P X Y A Defines loc P given coordinates (distances) and absolute bearing rel F T [L R A] Defines loc T: start at loc F, go forward L, translate right R, turn left A (defaults are all 0). extend F T len L [R] length L extend F T upto U [R] s.t. perpendicular at T passes through U extend F T ang A R subtending directionally A extend F T uptoang A R s.t. direction at T is A extend F T parallel U R s.t. direction at T is same as at U Draws an arc or line from loc F, defining the other end as loc T. If length R specified, draws an arc of radius R; R +ve curves to the right; R -ve to the left. join F T R [S ...] Joins one existing loc, F, to another, T. F's direction points to the new track; T's away - ie the added track leaves F in F's direction and arrives at T in T's direction. R is the minimum curve radius allowed. S selects from the available solutions, and may be any of the following long prefer longer length solution short prefer shorter length solution right|left prefer mostly bending to the left resp. right beginright|beginleft prefer first bend to the right endright|endleft prefer final bend to the right [!]twoarcs prefer [not] two circular arcs of equal radius [!]arcline prefer [not] one line and an arc of max radius [!]arcsline prefer [not] line between two arcs of min radius if this doesn't resolve, will pick the shortest. defobj O [commands] enddef Defines the object O. Inside the definition, the commands do not draw when the object is being defined. The object has its own coordinate space and its own location namespace. obj[flip] O A F [P] Places an instance of object O. The loc defined inside O as F (`formal parameter', F must be just ) is placed at existing loc A (`actual parameter'). If prefix P (syntax is that of an identifier) is specified, each other loc L inside O is exported into the global namespace as a new loc PL. P may be `=' to indicate an empty prefix (default is not to export locs). If `flip' is used then the object is placed with object-space y coordinates negated (ie, it is mirrored so that the object's North exchanges with South). Command-line options -D turn on debug (level 1) } currently only debug levels are -Dnnn set debug level to nnn } 0 (none) and 1 (some) -e[ARSCcLlMNOm]... Turn on and off drawing of elements in groups. These are abbreviations for various -E... options. track -E.... A full track ARSc R rails only aRsc S rails and sleepers only aRSc C centrelines only arsC c swept area and ticks only Arsc labels at locs L label top-level locs (turns on bars for them too) LM l do not label any locs l bars at locs (thick lines perp to track dir'n) M bars for top-level locs only Mno N bars for top-level locs and those in obj's MNo O bars for everything, including those inside parts MNO m no bars (turns off labelling too) mnol -E[ARSCLMNOarsclmno]... enable (capitals) or disable (lowercase) drawing of individual elements A draw track swept area, with ticks R draw track rails S draw track sleepers C draw track centrelines L label locs M mark locs with a bar N mark locs with a bar in objs O mark locs with a bar in parts