Returns the horizontal coordinate of a taxi flight's source node. Used in the default UI to draw lines between nodes;
TaxiNodeSetCurrent() should be called first so the client can compute routes.
See also Taxi/Flight functions.
source- Index of the source flight point (between 1 and
dest- Index of the destination flight point (between 1 and
sX- X coordinate of the source taxi node (as a proportion of the taxi map's width; 0 = left edge, 1 = right edge) (