1MAPITD(3NCARG)                   NCAR GRAPHICS                  MAPITD(3NCARG)
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NAME

6       MAPITD - Draws lines on a map.  MAPITD is just like MAPIT, but,
7       ultimately, DASHPACK routines are called instead of DASHCHAR routines.
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SYNOPSIS

10       CALL MAPITD (RLAT,RLON,IFST)
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C-BINDING SYNOPSIS

13       #include <ncarg/ncargC.h>
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15       void c_mapitd (float rlat, float rlon, int ifst)
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DESCRIPTION

18       RLAT and RLON
19                   (input expressions, of type REAL) specify the latitude and
20                   longitude of a point to which the "pen" is to be moved.
21                   Both are given in degrees. RLAT must be between -90. and
22                   +90., inclusive; RLON must be between -540. and +540.,
23                   inclusive.
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25       IFST        (an input expression, of type INTEGER) is 0 to do a "pen-
26                   up" move, 1 to do a "pen-down" move only if the distance
27                   from the last point to the new point is greater than 'MV'
28                   plotter units, and 2 or greater to do a "pen-down" move
29                   regardless of the distance from the last point to the new
30                   one.
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C-BINDING DESCRIPTION

33       The C-binding argument descriptions are the same as the FORTRAN
34       argument descriptions.
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USAGE

37       MAPITD is used to draw lines on the map.  MAPITD attempts to omit
38       nonvisible portions of lines and to handle "crossover," a jump from one
39       end of the map to the other caused by the projection of the globe onto
40       a flat surface. Crossover can occur on cylindrical and conical
41       projections; MAPITD handles it gracefully on the former and not so well
42       on the latter.
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44       To draw the projection of a line defined by a series of lat/lon
45       coordinates, start by calling MAPITD with the coordinates of the first
46       point and with IFST = 0.  Then, call MAPITD repeatedly with the
47       coordinates of the next point along the line and with IFST = 1 or 2.
48       (IFST = 2 is normally used only for the final point, to ensure closure
49       with a line drawn by another series of calls.)  Finally, if the next
50       thing your program does is STOP, call FRAME, or change attributes like
51       color or line width, you should call MAPIQD to flush MAPITD's buffers.
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53       The EZMAP parameter 'DL' determines whether MAPITD draws solid lines or
54       dotted lines. Dotted lines are drawn using calls to POINTS. Solid lines
55       are drawn using calls to DPFRST and DPVECT. The parameters 'DD' and
56       'MV' also affect MAPITD's behavior. See the descriptions of these
57       parameters in the ezmap_params man page.
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59       Keep in mind the following:
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61       ·   The projection of the line segment joining two points on the globe
62           is considered to be the straight-line segment joining the
63           projections of the points; no attempt is made to project it as if
64           it were a portion of a great circle.
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66       ·   If both endpoints of a line segment are visible, the segment is
67           considered to be entirely visible.
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69       ·   If both endpoints are invisible, the segment is considered to be
70           entirely invisible.
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72       ·   If one endpoint is visible and the other is not, a new point is
73           interpolated at the boundary between the visible and invisible
74           portions.  Only visible portions of the line are drawn.
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76       Because of these considerations, points defining a line should not be
77       too far apart on the globe.
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79       There are two types of boundaries between visible and invisible
80       regions:
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82       ·   The limb is a boundary between a projectable region and an
83           unprojectable one. The limb may be circular, elliptical, or some
84           other shape, depending on the projection being used. For example,
85           an orthographic projection has as its limb a circle, centered at
86           (0,0), with a radius of 1.
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88       ·   The perimeter is a rectangular or elliptical boundary defined by
89           EZMAP parameters set by you to specify the region you wish to view.
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EXAMPLES

92       None.
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ACCESS

95       To use MAPITD or c_mapitd, load the NCAR Graphics libraries ncarg,
96       ncarg_gks, and ncarg_c, preferably in that order.
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SEE ALSO

99       Online: ezmap, ezmap_params, mapaci, mapbla, mapblm, mapdrw, mapeod,
100       mapfst, mapgci, mapgrd, mapgrm, mapgtc, mapgti, mapgtl, mapgtr, mapint,
101       mapiq, mapiqa, mapiqd, mapiqm, mapit, mapita, mapitm, maplbl, maplmb,
102       maplot, mappos, maproj, maprs, maprst, mapsav, mapset, mapstc, mapsti,
103       mapstl, mapstr, maptra, maptri, maptrn, mapusr, mapvec, mpchln, mpfnme,
104       mpgetc, mpgeti, mpgetl, mpgetr, mpglty, mpiaty, mpifnb, mpilnb, mpiola,
105       mpiosa, mpipai, mpipan, mpipar, mpisci, mplnam, mplndm, mplndr, mplnri,
106       mpname, mprset, mpsetc, mpseti, mpsetl, mpsetr, supmap, supcon,
107       ncarg_cbind
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109       Hardcopy: NCAR Graphics Contouring and Mapping Tutorial
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112       Copyright (C) 1987-2009
113       University Corporation for Atmospheric Research
114       The use of this Software is governed by a License Agreement.
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118UNIX                              March 1993                    MAPITD(3NCARG)
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