1PCMPXY(3NCARG) NCAR GRAPHICS PCMPXY(3NCARG)
2
6 PCMPXY - This routine is normally not called directly by the user
7 (though it can be). It is called by each of the routines PCHIQU,
8 PCMEQU, and PCLOQU when the user has set the mapping flag ´MA´ nonzero
9 to request mapping of characters from one X/Y coordinate system to
10 another.
11
13 CALL PCMPXY (IMAP,XINP,YINP,XOTP,YOTP)
14
16 #include <ncarg/ncargC.h>
17 void c_pcmpxy (int imap, float xinp, float yinp, float *xotp, float
18 *yotp)
19
21 IMAP (an input expression of type INTEGER) specifies which
22 mapping is to be done. Whenever Plotchar routines call
23 PCMPXY, IMAP = ´MA´. The default version of PCMPXY
24 recognizes the following values of IMAP:
25 IMAP = 0
27 Type of mapping
29 None. When IMAP is zero, the routine PCMPXY is
30 being asked for information about its
31 capabilities with respect to a particular
32 mapping.
33 XINP
35 Input: the real equivalent of a possible value of
36 IMAP about which information is desired.
37 YINP
39 Output (real): 0. says that the mapping specified
40 by XINP is not available, 1. that it is
41 available, 2. that its inverse is available, and
42 3. that both it and its inverse are available.
43 IMAP = 1
45 Type of mapping
47 Ezmap projection.
48 XINP
50 Longitude, in degrees.
51 YINP
53 Latitude, in degrees.
54 IMAP = 2
56 Type of mapping
58 Rho/theta mapping.
59 XINP
61 Rho, in user units.
62 YINP
64 Theta, in degrees.
65 IMAP = 3
67 Type of mapping
69 Projection from an arbitrary parallelogram in
70 3-space to an image plane. This is implemented
71 using a package which is currently under
72 development and is not yet generally available.
73 XINP
75 A multiplier for a unit vector along one edge of
76 the parallelogram.
77 YINP
79 A multiplier for a unit vector along an
80 intersecting edge of the parallelogram.
81 IMAP = 4
83 Type of mapping
85 A version of the EZMAP projection that is
86 intended to be used to label specific points on
87 the surface of the globe. When 'MA' = 4, use
88 "0." for each of the arguments XPOS, YPOS, and
89 ANGD in calls to PCHIQU and PCMEQU. Initially,
90 each label is assumed to be placed at the point
91 on the globe with latitude zero and longitude
92 zero and to be written along the equator. Three
93 rotations are then performed to move the label to
94 the point (PLAT,PLON) in such a way that it makes
95 an angle PANG with the local eastward-pointing
96 vector. Finally, the EZMAP routine MAPTRA is
97 called to project the label as specified by the
98 current state of EZMAP. The desired values of
99 PANG, PLAT, and PLON (in degrees) are passed to
100 PCMPXY in the labelled common block PCMP04, which
101 contains just those three variables, in that
102 order. Use the ncargex command to see the
103 following relevant example: cpex10.
104 XINP
106 Longitude, in degrees.
107 YINP
109 Latitude, in degrees.
110 IMAP = 100
112 Type of mapping
114 The identity mapping, but returns 1.E12 outside a
115 specified viewport. Used by the utility
116 Scrolled_title to do clipping at the edges of the
117 viewport.
118 XINP
120 X coordinate, in the fractional system.
121 YINP
123 Y coordinate, in the fractional system.
124 other > 0
126 Type of mapping
128 The identity mapping.
129 XINP
131 Any real value.
132 YINP
134 Any real value.
135 other < 0
137 Type of mapping
139 An inverse mapping.
140 XINP
142 A mapped X coordinate.
143 YINP
145 A mapped Y coordinate.
146 Note: Values of IMAP less than or equal to zero are not
148 currently used by Plotchar in calling PCMPXY. The scheme
149 described is the same as that used for the routine CPMPXY,
150 in the NCAR Graphics package Conpack. It is possible that,
151 in the future, values of IMAP less than or equal to zero
152 will occur in calls to PCMPXY, so it is best to be
153 prepared.
154 XINP and YINP
156 (input expressions of type REAL) specify the X and Y
157 coordinates of a point to be mapped.
158 Note: When IMAP is less than or equal to zero (which cannot
160 currently happen, but may someday be possible), XINP and
161 YINP are used differently, as shown above.
162 XOTP and YOTP
164 (output variables of type REAL) in which PCMPXY returns the
165 mapped X and Y coordinates of the point. If the point is
166 not visible under the mapping selected (as, for example,
167 when the orthographic projection of Ezmap is being used and
168 the point to be mapped is on the other side of the globe),
169 PCMPXY must return, as a signal that this is the case,
170 whatever special nonzero value has been given to the
171 internal parameter ´OR´, so that the calling routine can
172 take appropriate action (to properly clip the character
173 being drawn, for example).
174 Note: When IMAP is less than or equal to zero (which cannot
176 currently happen, but may someday be possible), XOTP and
177 YOTP are used differently, as shown in the table above.
178
180 The C-binding argument descriptions are the same as the FORTRAN
181 argument descriptions.
182
184 This routine is normally not called directly by the user (though it can
185 be). It is called by each of the routines PCHIQU, PCMEQU, and PCLOQU
186 when the user has set the mapping flag ´MA´ nonzero to request mapping
187 of characters from one X/Y coordinate system to another. A call to
188 PCMPXY has the following form:
189 CALL PCMPXY (IMAP,XINP,YINP,XOTP,YOTP)
191 The default version of PCMPXY does several useful mappings; a user
193 version may be supplied to do others.
194
196 To use PCMPXY or c_pcmpxy, load the NCAR Graphics libraries ncarg,
197 ncarg_gks, and ncarg_c, preferably in that order.
198
200 Online: plotchar, pcdlsc, pcgetc, pcgeti, pcgetr, pchiqu, pcloqu,
201 pcmequ, pcpnwi, pcrset, pcsetc, pcseti, pcsetr, ncarg_cbind.
202 Hardcopy: NCAR Graphics Fundamentals, UNIX Version
204
206 Copyright (C) 1987-2009
207 University Corporation for Atmospheric Research
208 The use of this Software is governed by a License Agreement.
209UNIX August 1993 PCMPXY(3NCARG)