NAME

       MPCHLN - This routine is called repeatedly as boundary lines are processed by MPLNAM, MPLNDM, and MPLNDR.
       The default version of the routine does nothing.  A user-supplied version may take action to change
       various characteristics of the lines.

SYNOPSIS

       CALL MPCHLN (IACT,ILTY,IOAL,IOAR,NPTS,PNTS)

C-BINDING SYNOPSIS

       None.

DESCRIPTION

       IACT        (an  input  expression  of  type  INTEGER)  specifies which of the EZMAPB routines has called
                   MPCHLN and what that routine is doing or has done with  the  boundary  line  defined  by  the
                   arguments  NPTS and PNTS.  IACT is positive if the line is about to be processed, negative if
                   the line was just processed; its absolute value is 1 if the call  comes  from  MPLNAM  (which
                   puts  lines  into  an area map), 2 if the call comes from MPLNDM (which draws lines masked by
                   some area map), and 3 if the call comes from MPLNDR (which just draws lines).

       ILTY        (an input expression of type INTEGER) specifies the type of the line: 1 => a line  separating
                   land from water, 2 => a line separating one "continent" from another (as, for example, Africa
                   from  Eurasia,  North America from Central America, or Central America from South America), 3
                   => a line separating one country from another, 4 => a line separating one state from another,
                   and 5 => a line separating one county from another.

       IOAL and IOAR
                   (input/output variables of type INTEGER) are the identifiers of the areas  to  the  left  and
                   right,  respectively,  of  the  line.   (Left  and right are defined from the standpoint of a
                   viewer standing at point 1 of the line and looking toward point 2.)  The values of  IOAL  and
                   IOAR may be changed by a knowledgeable user.

       NPTS        (an  input/output  variable  of type INTEGER), on entry, is the number of points defining the
                   line.  NPTS may be zeroed by MPCHLN to suppress any use of the line by the calling routine.

       PNTS        (an input/output array, dimensioned 2*NPTS, of type REAL) is an array of  point  coordinates.
                   PNTS(1)  and  PNTS(2)  are the latitude and longitude of the first point, PNTS(3) and PNTS(4)
                   the latitude and longitude of the second point,  ...   PNTS(2*NPTS-1)  and  PNTS(2*NPTS)  the
                   latitude  and  longitude  of  the last point.  All values are in degrees.  Longitudes are all
                   between -180 and +180; no segment crosses the meridian at -180 (+180) degrees.

C-BINDING DESCRIPTION

       The C-binding argument description is the same as the FORTRAN argument description.

USAGE

       MPCHLN is called by each of the routines MPLNAM, MPLNDM, and  MPLNDR  just  before  and  just  after  the
       processing  of  each  boundary line read from a specified map database.  A user-supplied version may take
       action to change various characteristics of the lines.  For example, the area identifiers to be used  for
       the  line  can  be  changed, the line can be deleted entirely, and line styles, colors, and widths can be
       set.

EXAMPLES

       Use the ncargex command to see the following relevant example: mpex11.

ACCESS

       To use the default version of MPCHLN, load the NCAR Graphics libraries ncarg, and  ncarg_gks,  preferably
       in that order.  To supply your own version, just compile it and load it.

SEE ALSO

       Online:  ezmap,  ezmap_params,  mapaci,  mapbla,  mapblm, mapdrw, mapeod, mapfst, mapgci, mapgrd, mapgrm,
       mapgtc, mapgti, mapgtl, mapgtr, mapint, mapiq, mapiqa, mapiqd, mapiqm,  mapit,  mapita,  mapitd,  mapitm,
       maplbl,  maplmb,  maplot,  mappos, maproj, maprs, maprst, mapsav, mapset, mapstc, mapsti, mapstl, mapstr,
       maptra, maptri, maptrn, mapusr, mapvec, mpfnme, mpgetc, mpgeti, mpgetl, mpgetr, mpglty,  mpiaty,  mpifnb,
       mpilnb,  mpiola,  mpiosa, mpipai, mpipan, mpipar, mpisci, mplnam, mplndm, mplndr, mplnri, mpname, mprset,
       mpsetc, mpseti, mpsetl, mpsetr, supmap, supcon, ncarg_cbind

COPYRIGHT

       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research
       The use of this Software is governed by a License Agreement.

UNIX                                               April 1998                                     MPCHLN(3NCARG)