1TDPARA(3NCARG) NCAR GRAPHICS TDPARA(3NCARG)
2
6 TDPARA - Initialization routine for TDPACK, called to set the value of
7 certain internal values.
8
10 CALL TDPARA (UA00, VA00, WA00, UV10, VV10, WV10, UV01, VV01, WV01)
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13 #include <ncarg/ncargC.h>
14 void c_tdpara(float ua00, float va00, float wa00, float uv10, float
16 vv10, float wv10, float uv01, float vv01, float wv01)
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19 This routine may be thought of as an initialization routine or as just
20 a routine to access certain internal values; it simply transfers the
21 values of its arguments into TDPACK labelled common blocks for later
22 use by other TDPACK routines. These values define a "reference
23 parallelogram". Each point in the plane in which the parallelogram
24 lies can be identified by specifying its "parallelogram coordinates": a
25 pair of reals, one of which may be thought of as an "X" coordinate and
26 the other of which may be thought of as a "Y" coordinate.
27 Calls to TDPARA may be positioned without regard to calls to TDINIT
29 because the two routines do not affect one another. Redefining the
30 reference parallelogram affects the behavior of each of the routines
31 TDPRPA, TDPRPI, TDGRID, TDLBLA, and TDPLCH, each of which makes use of
32 parallelogram coordinates in some way. Be aware that each of the
33 routines TDGRDS and TDLBLS calls TDPARA to redefine the reference
34 parallelogram and neither of them restores the original definition when
35 it is done.
36 If a point has "parallelogram coordinates" (XIPA,YIPA), then its actual
38 3-space coordinates are given by the following equations:
39 U = UA00+XIPA*UV10+YIPA*UV01
41 V = VA00+XIPA*VV10+YIPA*VV01
42 W = WA00+XIPA*WV10+YIPA*WV01
43 The point with parallelogram coordinates (0,0) is in what might be
45 thought of as the "lower left" corner of the parallelogram, while the
46 point with parallelogram coordinates (1,1) is in what might be thought
47 of as the "upper right" corner of the parallelogram. Any point of the
48 plane in which the reference parallelogram lies can be identified using
49 its parallelogram coordinates, not just the points inside the
50 parallelogram itself.
51 Note that, although the reference parallelogram doesn't have to be
53 rectangular, a non-rectangular one is probably not very useful; in
54 fact, a square one defined by unit vectors is probably best,
55 particularly if one is drawing characters in the plane of the reference
56 parallelogram. For example, suppose that you want to write the
57 characters "THE U/V PLANE" in that part of the U/V plane with U values
58 between 0 and 100 and V values between 0 and 200; it is probably best,
59 in this case, to use a reference parallelogram with an origin at
60 (0,0,0), an "X" side with components (1,0,0) and a "Y" side with
61 components (0,1,0). Then, in the call to TDPLCH, one can place the
62 character string at parallelogram coordinates (50,100) and use a
63 character size of 1.5. If one used a reference parallelogram with an
64 origin at (0,0,0), an "X" side with components (100,0,0) and a "Y" side
65 with components (0,200,0), one could place the character string at
66 parallelogram coordinates (.5,.5) and use a character size of .015, but
67 the characters written would be twice as high as they are wide, which
68 is undesirable.
69 The arguments of TDPARA are as follows:
71 UA00, VA00, and WA00
73 (input expressions of type REAL) - the coordinates of the
74 "origin" of the parallelogram: the point with parallelogram
75 coordinates (0,0).
76 UV10, VV10, and WV10
78 (input expressions of type REAL) - the U, V, and W components
79 of the vector from the origin of the parallelogram to the point
80 with parallelogram coordinates (1,0).
81 UV01, VV10, and WV01
83 (input expressions of type REAL) - the U, V, and W components
84 of the vector from the origin of the parallelogram to the point
85 with parallelogram coordinates (0,1).
86
88 The C-binding argument descriptions are the same as the FORTRAN
89 argument descriptions.
90
92 To use TDPARA or c_tdpara, load the NCAR Graphics libraries ncarg,
93 ncarg_gks, and ncarg_c, preferably in that order.
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96 Online: tdclrs, tdctri, tddtri, tdgeti, tdgetr, tdgrds, tdgrid, tdgtrs,
97 tdinit, tditri, tdlbla, tdlbls, tdline, tdlnpa, tdmtri, tdotri, tdpack,
98 tdpack_params, tdplch, tdprpa, tdprpi, tdprpt, tdseti, tdsetr, tdsort,
99 tdstri, tdstrs
100
102 Copyright (C) 1987-2009
103 University Corporation for Atmospheric Research
104 The use of this Software is governed by a License Agreement.
105UNIX July 1997 TDPARA(3NCARG)