- Is it possible to modifiy in metapost the line which is dessined into 2 points map-connection ?: I took what maybe a simpler approach to that Tarquin describes, minimally altering the default metapost, but adding a clear start and end point to the map-connection line. What I discovered when attempting this was that arrow heads are intimately connected, in the default metapost, to map-connection lines. The example below is complicated by a change we made to refine the alignment of arrow heads when the incoming line is curved. If you want I could dig out the code prior to the arrow head change, but you can probably extract that from your own installation. Bruce #ARROW and MAP-CONNECTION REDEFINITIONS #-------------------------- #Edited Bruce Mutton Apr2018 Redefinition of map-connection line and arrow heads code metapost % Q = 0 -- none (no arrows) % 1 -- end (default) % 2 -- begin % 3 -- both def l_arrow (expr P, Q) = % Arrow heads rotated so that line path intersects middle of back of arrowhead. Johnny Willis 3Jun2023 T:=identity; pickup PenC; path Pcircle_s, Pcircle_e, ah_start, ah_end, p, P_mod, errcheck; pair sp, ep, int_start, int_end; numeric alength, c_diam; ep = point 0 of P; sp = point infinity of P; alength = 0.5u; c_diam = 2*alength; Pcircle_s = fullcircle scaled c_diam shifted sp; Pcircle_e = fullcircle scaled c_diam shifted ep; p := (-0.1u,-alength)--(-0,0)--(.1u,-alength)--cycle; errcheck = (ep) -- (sp); if arclength(errcheck) < alength: %if end points P shorter than arrow head, don't trim P int_end = ep; int_start = sp; ah_end = (sp) -- (ep); ah_start = (ep) -- (sp); else: %set up for trimming P at back of arrowheads int_end = Pcircle_e intersectionpoint P; int_start = Pcircle_s intersectionpoint P; ah_end = (int_end) -- (ep); ah_start = (int_start) -- (sp); fi; if Q = 0: % -head none P_mod = P; fi; if Q = 1: %arrow at end of line -head end draw p rotated (angle(thdir(ah_end,0))-90) shifted (point 0 of P); fill p rotated (angle(thdir(ah_end,0))-90) shifted (point 0 of P); P_mod = P cutbefore int_end; fi; if Q = 2: %arrow at start of line -head begin draw p rotated (angle(thdir(ah_start,0))-90) shifted (point infinity of P); fill p rotated (angle(thdir(ah_start,0))-90) shifted (point infinity of P); P_mod = P cutafter int_start; fi; if Q = 3: %arrow at both ends of line -head both draw p rotated (angle(thdir(ah_start,0))-90) shifted (point infinity of P); fill p rotated (angle(thdir(ah_start,0))-90) shifted (point infinity of P); draw p rotated (angle(thdir(ah_end,0))-90) shifted (point 0 of P); fill p rotated (angle(thdir(ah_end,0))-90) shifted (point 0 of P); P_mod = (P cutbefore int_end) cutafter int_start; fi; thdraw P_mod; enddef; def l_mapconnection (expr P) = thdrawoptions(dashed dashpattern(on 1bp off 2bp on 1bp off 2bp) scaled (2 * optical_zoom) withpen PenA); %draw map-connection line with arrowhead at end l_arrow(P,1); %How to double or triple arrowhead size with this call? %draw dot at start of map-connection line thdraw point infinity of P withpen pencircle scaled 0.3u; %Why infinity and not 0 for start?? %If point before arrow head, then point does not render in legend but does on map?? thdrawoptions(); enddef; endcode # and if necessary in some other layout… symbol-colour line map-connection [54 7 60] #purple symbol-show line map-connection #And then in th-config but outside of a layout… text en "line map-connection" "passage offset connection" #END
