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

6       DANDR - Draws an isosurface when used in conjunction with entry INIT3D.
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SYNOPSIS

9       CALL DANDR (NV,NW,ST1,LX,NX,NY,IS2,IU,S,IOBJS,MV)
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STATUS

12       This routine is part of the obsolete Isosrfhr utility.  Isosrfhr has
13       been replaced by the Isosurface utility.  To see the Isosurface utility
14       overview man page, type "man isosurface".
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DESCRIPTION

17       NV          (an input expression of type INTEGER) defines the range to
18                   be used for the V dimension of the 3-D UVW grid.
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20       NW          (an input expression of type INTEGER) defines the range to
21                   be used for the W dimension of the 3-D UVW grid.
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23       ST1         (an input array of type REAL) used as scratch work space.
24                   It must be dimensioned at least of size NV*NW*2 words.
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26       LX          (an input array of type INTEGER) which is the first
27                   dimension of array IS2.  It must be of a length to hold NX
28                   bits.  On a 64 bit machine it would be LX=(NX-1)/64+1.
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30       NX          (an input expression of type INTEGER) defines the range of
31                   cells in the X-direction of the XY pixel model of the image
32                   plane.  A silhouette of the parts of the picture processed
33                   so far is stored in this model.  Lines to be drawn are
34                   tested for visibility by examining the silhouette.  Lines
35                   in the silhouette are hidden.  Lines out of the silhouette
36                   are visible.  The solution is approximate because the
37                   silhouette is not formed exactly.  See IS2.
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39       NY          (an input expression of type INTEGER) defines the range of
40                   cells in the Y-direction of the XY pixel model of the image
41                   plane.  NY is also the second dimension of array IS2.
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43       IS2         (an input array of type INTEGER) which holds the XY pixel
44                   model of the image plane.  It is dimensioned LX by NY.  The
45                   pixel model contains NX by NY elements.  The sizes of NX
46                   and NY vary with the choice of options.  For example, if
47                   hidden lines are drawn, NX and NY (and LX) can be smaller
48                   than when hidden lines are not drawn.  If some visible
49                   lines are not drawn, NX and NY (and LX) must be made
50                   larger.  As a guide, some examples which have been adequate
51                   are:
52                        GIVEN                 USE
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54                       NU  NV  NW            NX  NY
55                   --------------------------------
56                      100 100  60           200 200
57                       60  60  60           110 110
58                       40  40  40            75  75
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61       IU          (an input expression of type INTEGER) defines the unit
62                   number of a scratch file for the package.  ST1 will be
63                   written NU times on this file.
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65       S           (an input array of type REAL, dimensioned 4) contains the
66                   world coordinates of the area where the picture is to be
67                   drawn.  That is, all plotting coordinates generated will be
68                   bounded as follows:  X coordinates will be between S(1) and
69                   S(2), Y coordinates will be between S(3) and S(4).  To
70                   prevent distortion, have S(2)-S(1) = S(4)-S(3).
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72                   All coordinates should be in a range between 10.  and 1010.
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74       IOBJS       (an input array of type INTEGER) which describes the
75                   objects to be drawn in VW space.  It is of size NV by NW.
76                   The actual first dimension of IOBJS in the calling program
77                   is MV.
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79                   Entry DANDR is called NU times to process any object
80                   contours in the VW cross sections defined by IOBJS.  Slabs
81                   are processed from back to front such that on the I-th call
82                   to DANDR, the slab at U = NU+1-I is processed.  IOBJS(J,K)
83                   = 1 if any object contains the point (NU+1-I,J,K) and
84                   IOBJS(J,K) = 0 otherwise.
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86       MV          (an input expression of type INTEGER) defines the actual
87                   first dimension of the array IOBJS in the calling program.
88                   When plotting all of IOBJS, NV = MV.
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USAGE

91       Entries DANDR and DANDR must be used in tandem to create a plot.  First
92       call entry DANDR to create a set of 2-D perspective planes which are
93       output to a scratch file.  Then, in the calling program you must loop
94       over the U dimension of UVW space starting at the last slab, NU, and
95       moving forward to slab 1.  Initially set all elements of IOBJS to
96       zeros.  Then, at all locations (J,K) where the surface of an object
97       would appear, set IOBJS(J,K) = 1.  When IOBJS(J,K) has been defined for
98       that VW slab (U = NU - I + 1), call the entry DANDR, which draws any
99       object contours based on the 2-D perspective defined for that slab.
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101       An Isosrfhr example of the logical structure of a program follows:
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103        C  Entry DANDR writes NU 2-D perspective planes, ST1(NV,NW,2),
104        C   of the UVW grid, viewed from the position EYE, to a scratch file.
105        C
106             CALL DANDR(EYE,NU,NV,NW,ST1,LX,NY,IS2,IU,S)
107        C
108        C NU is the extent of the U dimension.
109        C
110             DO 1 IBKWDS = 1,NU
111             I = NU+1-IBKWDS
112        C
113        C You must define the presence of the objects at each VW grid point for
114        C all slabs in the U direction. Ones are used to indicate the presence
115        C of an object.  Zeros indicate no object.
116        C
117        C      IF (OBJ.EQ.YES) IOBJS(J,K) = 1
118        C      IF (OBJ.EQ.NO)  IOBJS(J,K) = 0
119        C
120        C  DANDR reads ST1(NV,NW,2) for slab I.
121        C
122           1 CALL DANDR(NV,NW,ST1,LX,NX,NY,IS2,IU,S,IOBJS,MV)
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EXAMPLES

126       Use the ncargex command to see the following relevant examples:  tisohr
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ACCESS

129       To use DANDR load the NCAR Graphics libraries ncarg, ncarg_gks, and
130       ncarg_c, preferably in that order.
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SEE ALSO

133       Online: isosrfhr, init3d, isosurface, isosurface_params, ezisos,
134       isgeti, isgetr, isseti, issetr, pwrzi, ncarg_cbind
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137       Copyright (C) 1987-2009
138       University Corporation for Atmospheric Research
139       The use of this Software is governed by a License Agreement.
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143UNIX                              March 1993                     DANDR(3NCARG)
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