Provided by: libncarg-dev_6.1.2-7_amd64 bug

NAME

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

SYNOPSIS

       CALL INIT3D (EYE,NU,NV,NW,ST1,LX,NY,IS2,IU,S)

STATUS

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  Isosrfhr has been replaced by the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

DESCRIPTION

       EYE         (an input array of type REAL, dimensioned 3) is the position of the eye in the
                   UVW coordinate system.  Objects are considered to be in a box with 2 extreme
                   corners at (1,1,1) and (NU,NV,NW).  The eye position must have positive
                   coordinates away from the coordinate planes U = 0, V = 0, and W = 0.  While
                   gaining experience with the package, use EYE(1) = 5.*NU, EYE(2) = 4.*NV, and
                   EYE(3) = 3.*NW.

       NU          (an input expression of type INTEGER) defines the range to be used for the U
                   dimension of the 3-D UVW grid.

       NV          (an input expression of type INTEGER) defines the range to be used for the V
                   dimension of the 3-D UVW grid.

       NW          (an input expression of type INTEGER) defines the range to be used for the W
                   dimension of the 3-D UVW grid.

       ST1         (an input array of type REAL) used as scratch work space.  It must be
                   dimensioned at least of size NV*NW*2 words.

       LX          (an input array of type INTEGER) which is the first dimension of array IS2.
                   It must be of a length to hold NX bits.  On a 64 bit machine it would be
                   LX=(NX-1)/64+1.

       NY          (an input expression of type INTEGER) defines the range of cells in the Y-
                   direction of the XY pixel model of the image plane.  NY is also the second
                   dimension of array IS2.

       IS2         (an input array of type INTEGER) which holds the XY pixel model of the image
                   plane.  It is dimensioned LX by NY.  The pixel model contains NX by NY
                   elements.  The sizes of NX and NY vary with the choice of options.  For
                   example, if hidden lines are drawn, NX and NY (and LX) can be smaller than
                   when hidden lines are not drawn.  If some visible lines are not drawn, NX and
                   NY (and LX) must be made larger.  As a guide, some examples which have been
                   adequate are:
                        GIVEN                 USE

                       NU  NV  NW            NX  NY
                   --------------------------------
                      100 100  60           200 200
                       60  60  60           110 110
                       40  40  40            75  75

       IU          (an input expression of type INTEGER) defines the unit number of a scratch
                   file for the package.  ST1 will be written NU times on this file.

       S           (an input array of type REAL, dimensioned 4) contains the world coordinates of
                   the area where the picture is to be drawn.  That is, all plotting coordinates
                   generated will be bounded as follows:  X coordinates will be between S(1) and
                   S(2), Y coordinates will be between S(3) and S(4).  To prevent distortion,
                   have S(2)-S(1) = S(4)-S(3).

                   All coordinates should be in a range between 10.  and 1010.

USAGE

       Entries INIT3D and DANDR must be used in tandem to create a plot.  First call entry INIT3D
       to create a set of 2-D perspective planes which are output to a scratch file.  Then, in
       the calling program you must loop over the U dimension of UVW space starting at the last
       slab, NU, and moving forward to slab 1.  Initially set all elements of IOBJS to zeros.
       Then, at all locations (J,K) where the surface of an object would appear, set IOBJS(J,K) =
       1.  When IOBJS(J,K) has been defined for that VW slab (U = NU - I + 1), call the entry
       DANDR, which draws any object contours based on the 2-D perspective defined for that slab.

       An Isosrfhr example of the logical structure of a program follows:

        C  Entry INIT3D writes NU 2-D perspective planes, ST1(NV,NW,2),
        C   of the UVW grid, viewed from the position EYE, to a scratch file.
        C
             CALL INIT3D(EYE,NU,NV,NW,ST1,LX,NY,IS2,IU,S)
        C
        C NU is the extent of the U dimension.
        C
             DO 1 IBKWDS = 1,NU
             I = NU+1-IBKWDS
        C
        C You must define the presence of the objects at each VW grid point for
        C all slabs in the U direction. Ones are used to indicate the presence
        C of an object.  Zeros indicate no object.
        C
        C      IF (OBJ.EQ.YES) IOBJS(J,K) = 1
        C      IF (OBJ.EQ.NO)  IOBJS(J,K) = 0
        C
        C  DANDR reads ST1(NV,NW,2) for slab I.
        C
           1 CALL DANDR(NV,NW,ST1,LX,NX,NY,IS2,IU,S,IOBJS,MV)

EXAMPLES

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

ACCESS

       To use INIT3D load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably
       in that order.

SEE ALSO

       Online: isosrfhr, dandr, isosurface, isosurface_params, ezisos, isgeti, isgetr, isseti,
       issetr, pwrzi, ncarg_cbind

COPYRIGHT

       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research
       The use of this Software is governed by a License Agreement.