1MAPIT(3NCARG)                    NCAR GRAPHICS                   MAPIT(3NCARG)
2
3
4

NAME

6       MAPIT - Draws lines on a map.
7

SYNOPSIS

9       CALL MAPIT (RLAT,RLON,IFST)
10

C-BINDING SYNOPSIS

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

DESCRIPTION

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

C-BINDING DESCRIPTION

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

USAGE

36       MAPIT is used to draw lines on the map; it is called by EZMAP itself
37       and, if desired, by the user. MAPIT attempts to omit nonvisible
38       portions of lines and to handle "crossover," a jump from one end of the
39       map to the other caused by the projection of the globe onto a flat
40       surface. Crossover can occur on cylindrical and conical projections;
41       MAPIT handles it gracefully on the former and not so well on the
42       latter.
43
44       To draw the projection of a line defined by a series of lat/lon
45       coordinates, start by calling MAPIT with the coordinates of the first
46       point and with IFST = 0.  Then, call MAPIT 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 MAPIQ to flush MAPIT's buffers.
52
53       The EZMAP parameter 'DL' determines whether MAPIT draws solid lines or
54       dotted lines. Dotted lines are drawn using calls to POINTS. Solid lines
55       are drawn using calls to DASHD, FRSTD, and VECTD. The parameters 'DD'
56       and 'MV' also affect MAPIT's behavior. See the descriptions of these
57       parameters in the ezmap_params man page.
58
59       Keep in mind the following:
60
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.
65
66       ·   If both endpoints of a line segment are visible, the segment is
67           considered to be entirely visible.
68
69       ·   If both endpoints are invisible, the segment is considered to be
70           entirely invisible.
71
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.
75
76       Because of these considerations, points defining a line should not be
77       too far apart on the globe.
78
79       There are two types of boundaries between visible and invisible
80       regions:
81
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.
87
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.
90

EXAMPLES

92       Use the ncargex command to see the following relevant examples: cmpgci,
93       cmptra, mpexfi.
94

ACCESS

96       To use MAPIT or c_mapit, load the NCAR Graphics libraries ncarg,
97       ncarg_gks, and ncarg_c, preferably in that order.
98

SEE ALSO

100       Online: ezmap, ezmap_params, mapaci, mapbla, mapblm, mapdrw, mapeod,
101       mapfst, mapgci, mapgrd, mapgrm, mapgtc, mapgti, mapgtl, mapgtr, mapint,
102       mapiq, mapiqa, mapiqd, mapiqm, mapita, mapitd, mapitm, maplbl, maplmb,
103       maplot, mappos, maproj, maprs, maprst, mapsav, mapset, mapstc, mapsti,
104       mapstl, mapstr, maptra, maptri, maptrn, mapusr, mapvec, mpchln, mpfnme,
105       mpgetc, mpgeti, mpgetl, mpgetr, mpglty, mpiaty, mpifnb, mpilnb, mpiola,
106       mpiosa, mpipai, mpipan, mpipar, mpisci, mplnam, mplndm, mplndr, mplnri,
107       mpname, mprset, mpsetc, mpseti, mpsetl, mpsetr, supmap, supcon,
108       ncarg_cbind
109
110       Hardcopy: NCAR Graphics Contouring and Mapping Tutorial
111
113       Copyright (C) 1987-2009
114       University Corporation for Atmospheric Research
115       The use of this Software is governed by a License Agreement.
116
117
118
119UNIX                              March 1993                     MAPIT(3NCARG)
Impressum