dandr(3NCARG)
NAME
DANDR - Draws an isosurface when used in conjunction with entry INIT3D.
SYNOPSIS
CALL DANDR (NV,NW,ST1,LX,NX,NY,IS2,IU,S,IOBJS,MV)
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 Isosrfhr has been replaced by the Isosurface utility.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
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.
NX (an input expression of type INTEGER) defines the range of
cells in the X-direction of the XY pixel model of the image
plane. A silhouette of the parts of the picture processed
so far is stored in this model. Lines to be drawn are
tested for visibility by examining the silhouette. Lines
in the silhouette are hidden. Lines out of the silhouette
are visible. The solution is approximate because the
silhouette is not formed exactly. See IS2.
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.
IOBJS (an input array of type INTEGER) which describes the
objects to be drawn in VW space. It is of size NV by NW.
The actual first dimension of IOBJS in the calling program
is MV.
Entry DANDR is called NU times to process any object
contours in the VW cross sections defined by IOBJS. Slabs
are processed from back to front such that on the I-th call
to DANDR, the slab at U = NU+1-I is processed. IOBJS(J,K)
= 1 if any object contains the point (NU+1-I,J,K) and
IOBJS(J,K) = 0 otherwise.
MV (an input expression of type INTEGER) defines the actual
first dimension of the array IOBJS in the calling program.
When plotting all of IOBJS, NV = MV.
USAGE
Entries DANDR and DANDR must be used in tandem to create a plot. First
call entry DANDR 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 DANDR 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 DANDR(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 DANDR load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in that order.
SEE ALSO
Online: isosrfhr, init3d, 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.
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
