Class GSTrackSearch

2010-08-22T16:42:20Z

Fwassner:

*[[TrainzScript Language Reference|API Hierarchy]]
**GSTrackSearch
 

*A class enabling the searching of a length of track for [[class Trackside|Trackside]] items.
*The GSTrackSearch class provides an interface to access certain items along a track in a specified direction from an existing trackside item.
*A GSTrackSearch object can be obtained by calling the [[Class Trackside#BeginTrackSearch|BeginTrackSearch()]] method on the [[class Trackside|Trackside]] item that you want to start your search from.
*The SearchNext() and GetMapObject() methods are provided to get a reference to a discovered [[class Trackside|Trackside]] object.
*The reference returned by these methods can be cast to [[class Trackside|Trackside]] child classes to find out if that item is in fact a [[class Signal|Signal]] or a [[class Junction|Junction]] for instance. As the script code doesn't know what the next item will be, always verify the cast.
*Since [[class Vehicle|Vehicles]] and [[Class Locomotive|Locomotives]] descend from [[class Trackside|Trackside]], searches can be initiated from rolling stock and rolling stock will be returned.
*GSTrackSearch methods will also find [[Class SceneryWithTrack|SceneryWithTrack]] and descendants, although the information which can be obtained from them is limited and these objects cannot be used to initiate a search.
*The search will continue (following the direction set by any junctions) until it is blocked by:
**A junction set against the track
**A turntable.
**A crossing. *** ? "crossing" appears to mean a track (diamond, etc), rather than a road (grade, level) crossing, since the function appears to work properly across road crossings.
**The end of the line.
 
*See [[TrackSearch]] for details of enhancements being developed for future versions of the game.
 

==Trackside.BeginTrackSearch==
{{MethodHeader|public native GSTrackSearch Trackside.BeginTrackSearch(bool direction)}}
*This method is called on objects descending from the [[class Trackside|Trackside]] class to obtain a GSTrackSearch object in the specified search direction.
*See [[Class Trackside#BeginTrackSearch|Trackside.BeginTrackSearch()]] for details.
 

==GetDistance==
{{MethodHeader|public native float GetDistance(void)}}
;Parameters
*None
;Returned Value
*The distance in metres from the origin of the search to the object at which the search cursor is currently pointing.
;Syntax
float distance = gst.GetDistance();
;Notes
*See [[#Code Examples|Code Examples]]
 

==GetFacingRelativeToSearchDirection==
{{MethodHeader|public native bool GetFacingRelativeToSearchDirection(void)}}
;Parameters
*None
;Returned Value
*True if the returned object orientation matches the direction of search, false otherwise.
;Syntax
bool facing = gst.GetFacingRelativeToSearchDirection();
;Notes
*Note that it is the direction of the search that matters, not the facing direction of the search origin.
*A search forwards from a fixed object such as a [[Class Trigger|Trigger]] will return '''true''' for any returned trigger which has the same orientation as the source.
*A search backwards from a fixed object such as a [[Class Trigger|Trigger]] will return '''false''' for any returned trigger which has the same orientation as the source.
 

==GetMapObject==
{{MethodHeader|public native MapObject GetMapObject(void)}}
;Parameters
*None
;Returned Value
*A reference to a MapObject or null if nothing has been found.
;Syntax
MapObject mo = gst.GetMapObject();
;Notes
*MapObject returns Trackside descendants including Vehicles and SceneryWithTrack descendants including Industries.
*Ensure that you attempt a cast to SceneryWithTrack and Trackside if you want the maximum possible amount of information from the search.
 

==SearchNext==
{{MethodHeader|public native MapObject SearchNext(void)}}
;Parameters
*None
;Returned Value
*A reference to a MapObject or null if nothing has been found.
;Syntax
MapObject mo = gst.GetMapObject();
;Notes
*SearchNext moves the search cursor to the next object if such an object exists.
 

==Known Issues==
*GSTrackSearch will return a null reference if it finds certain types of [[Class Crossing|Crossing]] objects, but will continue searching beyond them if asked. As a result of this it is often necessary to make repeated calls to SearchNext following a null return to decide whether you have reached the end of the track or whether your search has simply been interrupted by one or more crossings.
 

==Code Examples==
*This code fragment implements a search forwards from a locomotive. The distance from the locomotive to any discovered object is printed to ''jetlog.txt''
*The process continues until the search returns a null value (which might be a crossing or the end of the track) or the distance from the train exceeds 1km.
GSTrackSearch gst = Loco.BeginTrackSearch(true); // obtain a GSTrackSearch object
MapObject mo = gst.SearchNext(); // initiate the search
while (mo) { // continue as long as objects are present
float distance = mo.GetDistance(); // how far ahead the object is
if (distance() > 1000.0) break; // break from the loop if the distance exceeds 1km
Interface.Print("object found at " distance " metres"); // print out the results
mo = gst.SearchNext(); // search for the next object
}
 

==Related Methods==
[[Class Trackside#BeginTrackSearch|Trackside.BeginTrackSearch()]]

==Categories==
[[Category:Script Class]]

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Class GSTrackSearch