Provided by: libncarg-dev_6.1.2-7_amd64 
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 Isosrfhr has been replaced by the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.