1VVUDMV(3NCARG) NCAR GRAPHICS VVUDMV(3NCARG)
2
6 VVUDMV - This routine is the user-definable external subroutine used to
7 draw masked vectors. The default version of the routine draws any
8 polyline all of whose area identifiers are greater than or equal to
9 zero.
10
12 CALL VVUDMV (XCS,YCS,NCS,IAI,IAG,NAI)
13
15 XCS (REAL array, assumed size NCS, input): Array of X
16 coordinates of the points defining the polyline with the
17 given set of area identifiers.
18 YCS (REAL array, assumed size NCS, input): Array of Y
20 coordinates of the points defining the polyline with the
21 given set of area identifiers.
22 NCS (INTEGER, input): Number of points; assumed size of the X
24 and Y coordinate arrays, XCS and YCS.
25 IAI (INTEGER array, assumed size NAI, input): Array of area
27 identifier values. Each value represents the area
28 identifier with respect to the area group in the area group
29 array with the same array index.
30 IAG (INTEGER array, assumed size NAI, input): Array of area-
32 identifier groups.
33 NAI (INTEGER, input): Number of area identifier groups. The
35 current version of Vectors supports up to 64 area groups.
36
38 ´VVUDMV´ is the name given to the default version of the masked vector
39 drawing routine, and it is also the name given to the argument through
40 which the external subroutine is passed to VVECTR. However, you may
41 choose any acceptable FORTRAN identifier as the name of a user-defined
42 version of the routine. The substitute routine must have an argument
43 list equivalent to the default version of VVUDMV. Also, whether or not
44 the default version is used, the subroutine that calls VVECTR should
45 contain an external declaration of the routine similar to the
46 following:
47 EXTERNAL VVUDMV
49 If the MSK parameter is set to the value 1, specifying high precision
51 masking, Vectors sends one set of X and Y polyline coordinate arrays to
52 the area masking routine, ARDRLN, for each vector arrow. ARDRLN
53 subdivides the polyline into pieces such that each smaller polyline has
54 a single area identifier with respect to each area identifier group,
55 then makes a call to VVUDMV for each polyline piece. While the default
56 version of VVUDMV only checks to see that none of the area identifiers
57 are negative, a user-defined version could perform more complicated
58 decision processing based on knowledge of the meaning of specific area
59 identifier groups and/or area identifier values. Note that, before
60 invoking VVUDMV, ARDRLN modifies the user coordinate space by making
61 the following calls:
62 CALL GETSET(VPL,VPR,VPB,VPT,WDL,WDR,WDB,WDT,LLG) CALL
64 SET(VPL,VPR,VPB,VPT,VPL,VPR,VPB,VPT,1)
65 These calls temporarily turn the user to NDC mapping into an identity,
67 allowing the user to call any of the routines, CURVE, CURVED, or the
68 GKS routine GPL, to render the polygon piece , without worrying about a
69 possible non-identity mapping between user and world coordinates.
70 If MSK has a value greater than 1, specifying low precision masking,
72 Vectors calls the routine ARGTAI to get the area identifiers with
73 respect to the area identifier groups for a single point that locates
74 the base position of the vector. Vectors then calls the VVUDMV routine
75 itself, passing the coordinate arrays for a complete vector arrow.
76 Thus, a vector arrow whose base position is within an area to be masked
77 can be eliminated, but an arrow whose base position is nearby, but
78 outside, a masked area may intrude into the area. Also, in this case,
79 since faster rendering is the goal, Vectors does not convert the
80 coordinate arrays into normalized device coordinates and do the
81 identity SET call. Therefore, the user should use only CURVE or CURVED
82 to render the polyline, unless there is no possibility of a non-
83 identity user to world coordinate mapping.
84 The current version of Vectors supports masked drawing with up to 64
86 area groups. Vectors will exit with an error message if an area map
87 with more than 64 groups is passed to it.
88
90 Use the ncargex command to see the following relevant examples: ffex05,
91 vvex01.
92
94 To use VVUDMV, load the NCAR Graphics libraries ncarg, ncarg_gks, and
95 ncarg_c, preferably in that order.
96
98 Online: vectors, vectors_params, vvectr, vvgetc, vvgeti, vvgetr,
99 vvinit, vvrset, vvsetc, vvseti, vvsetr, vvumxy, ncarg_cbind.
100 Hardcopy: NCAR Graphics Fundamentals, UNIX Version
102
104 Copyright (C) 1987-2007
105 University Corporation for Atmospheric Research
106 This documentation is free software; you can redistribute it and/or
108 modify it under the terms of the GNU General Public License as
109 published by the Free Software Foundation; either version 2 of the
110 License, or (at your option) any later version.
111 This software is distributed in the hope that it will be useful, but
113 WITHOUT ANY WARRANTY; without even the implied warranty of
114 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
115 General Public License for more details.
116 You should have received a copy of the GNU General Public License along
118 with this software; if not, write to the Free Software Foundation,
119 Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
120UNIX April 1993 VVUDMV(3NCARG)