[Federal Register Volume 59, Number 116 (Friday, June 17, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-14779]
[[Page Unknown]]
[Federal Register: June 17, 1994]
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DEPARTMENT OF COMMERCE
[Docket No. 940541-4141]
RIN No. 0693-AB30
Proposed Revision of Federal Information Processing Standard
(FIPS) 153, Programmer's Hierarchical Interactive Graphics Systems
(PHIGS)
AGENCY: National Institute of Standards and Technology (NIST),
Commerce.
ACTION: Notice; request for comments.
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SUMMARY: A revision of FIPS 153, PHIGS, is being proposed. This
proposed revision will add features to the basic PHIGS functionality
defined in FIPS 153, which adopts voluntary industry standards, ANSI/
ISO 9592.1-3:1989, and ANSI/ISO 9593-1:1990, 9593-3:1990, 9593-4:1991.
The basic PHIGS functionality provides for control and data interchange
between an application program and its graphic support systems and for
a set of functions and programming language bindings for the
definition, display and modification of two-dimensional (2D) or three-
dimensional (3D) graphic data. New features will be provided by the
proposed adoption of voluntary industry specifications ANSI/ISO
9592.1a,2a,3a,4:1992 for PHIGS PLUS. PHIGS PLUS will augment the basic
PHIGS functionality by providing facilities for specifying curved
lines, curved and facetted surfaces, lighting and shading, and color.
In addition, the proposed revision will add a requirement for the
validation of PHIGS implementations using either FORTRAN or C bindings.
Prior to the submission of this proposed revision to FIPS 153 to
the Secretary of Commerce for review and approval, it is essential to
assure that consideration is given to the needs and views of
manufacturers, the public, and State and local governments. The purpose
of this notice is to solicit such views.
This proposed revision contains two sections: (1) An announcement
section, which provides information concerning the applicability,
implementation, and maintenance of the standard; and (2) a
specifications section. Only the announcement section of the standard
is provided in this notice. Interested parties may obtain copies of the
specifications (ANSI/ISO 9592.1-3:1989, ANSI/ISO 9592.1a,2a,3a,4:1992,
and ANSI/ISO 9593-1:1990, 9593-3:1990, 9593-4:1991) from American
National Standards Institute (ANSI), 11 West 42nd Street, 13th floor,
New York, NY 10036, (212) 642-4900.
DATES: Comments on this proposed revision must be recived on or before
September 15, 1994.
ADDRESSES: Written comments concerning the adoption of this proposed
revision should be sent to: Director, Computer Systems Laboratory,
ATTN: Proposed Revision of FIPS 153, PHIGS, Technology Building, room
B154, National Institute of Standards and Technology, Gaithersburg, MD
20899.
Written comments received in response to this notice will be made
part of the public record and will be made available for inspection and
copying in the Central Reference and Records Inspection Facility, room
6020, Herbert C. Hoover Building, 14th Street between Pennsylvania and
Constitution Avenues, NW., Washington, DC 20230.
FOR FURTHER INFORMATION CONTACT:
Mr. Kevin G. Brady, National Institute of Standards and Technology,
Gaithersburg, MD 20899, telephone (301) 975-3644.
Dated: June 13, 1994.
Samuel Kramer,
Associate Director.
Proposed Federal Information Processing Standards Publication 153-1
(date)
Announcing the Standard for Programmer's Hierarchical Interactive
Graphics System (PHIGS)
Federal Information Processing Standards Publications (FIPS
PUBS) are issued by the National Institute of Standards and
Technology after approval by the Secretary of Commerce pursuant to
section 111(d) of the Federal Property and Administrative Services
Act of 1949 as amended by the Computer Security Act of 1987, Public
Law 100-235.
1. Name of Standard. Programmer's Hierarchical Interactive
Graphics System (PHIGS) (FIPS PUB 153-1).
2. Category of Standard. Software Standard, Graphics.
3. Explanation. This publication is a revision of FIPS PUB 153
and supersedes that document in its entirety. This revision provides
a substantial, upward-compatible enhancement of the basic PHIGS
functionality known as Plus Lumiere and Surfaces, PHIGS PLUS (ANSI/
ISO 9592.1a,2a,3a,4:1992). PHIGS PLUS adds facilities for the
specification of curved lines, curved and facetted surfaces,
lighting and shading, and adds a mechanism for color specification
to allow non-indexed color specification. Amendments to each part of
the PHIGS specification detail revisions required by PHIGS PLUS.
Also, each language binding of PHIGS has been amended as a result of
PHIGS PLUS. The specifications and amendments that comprise the
complete PHIGS standard as a result of this revision are detailed in
the Specification section of this document.
In addition this revision adds a requirement for validation of
PHIGS implementations using either FORTRAN or C bindings. However,
validation is currently limited to basic PHIGS functionality, and
therefore does not include the new functionality of PHIGS PLUS added
by this revision.
FIPS 153-1 adopts the American National Standard Programmer's
Hierarchical Interactive Graphics System, ANSI/ISO 9592.1-3:1989,
and ANSI/ISO 9592.1a,2a,3a,4:1992, and 9593.1:1990, 9593.3:1990,
9593.4:1991, as a Federal Information Processing Standard (FIPS).
This standard specifies the control and data interchange between an
application program and its graphic support system. It provides a
set of functions and programming language bindings for the
definition, display and modification of two-dimensional (2D) or
three-dimensional (3D) graphical data. In addition, these language
bindings allow for the definition, display and modification of
geometrically related objects, graphical data, and the relationships
between the graphical data. The purpose of the standard is to
promote portability of graphics application programs between
different installations. The standard is for use by implementors as
the reference authority in developing graphics software systems; and
by other computer professionals who need to know the precise
syntactic and semantic rules of the standard.
4. Approving Authority. Secretary of Commerce.
5. Maintenance Agency. U.S. Department of Commerce, National
Institute of Standards and Technology (NIST), Computer Systems
Laboratory (CSL).
6. Cross Index.
a. ANSI/ISO 9592.1:1989, Information Processing Systems--
Computer Graphics--Programmer's Hierarchical Interactive Graphics
System (PHIGS), Part 1, Functional Description.
b. ANSI/ISO 9592.1a:1992, Amendment 1, Information Processing
Systems--Computer Graphics--Programmer's Hierarchical Interactive
Graphics System (PHIGS), Part 1, Functional Description.
c. ANSI/ISO 9292.2:1989, Information Processing Systems--
Computer Graphics--Programmer's Hierarchical Interactive Graphics
System (PHIGS), Part 2, Archive File Format.
d. ANSI/ISO 9492.2a:1992, Amendment 1, Information Processing
Systems--Computer Graphics--Programmer's Hierarchical Interactive
Graphics System (PHIGS), Part 2, Archive File Format.
e. ANSI/ISO 9592.3:1989, Information Processing Systems--
Computer Graphics--Programmer's Hierarchical Interactive Graphics
System (PHIGS), Part 3, Clear Text Encoding of Archive File.
f. ANSI/ISO 9592.3a:1992, Amendment 1, Information Processing
Systems--Computer Graphics--Programmer's Hierarchical Interactive
Graphics System (PHIGS), Part 3, Clear Text Encoding of Archive
File.
g. ANSI/ISO 9592.4:1992, Information Processing Systems--
Computer Graphics--Programmer's Hierarchical Interactive Graphics
System (PHIGS), Part 4, Plus Lumiere and Surfaces, PHIGS PLUS.
h. ANSI/ISO 9593.1:1990, Information Processing Systems--
Computer Graphics--Programmer's Hierarchical Interactive Graphics
System (PHIGS), Language Bindings, FORTRAN.
i. ANSI/IEC 9593.1:1990 Tech. Corrigendum, Programmer's
Hierarchical Interactive Graphics System (PHIGS), Language Bindings,
FORTRAN.
j. ANSI/ISO 9593.3:1990, Information Processing Systems--
Computer Graphics--Programmer's Hierarchical Interactive Graphics
System (PHIGS), Language Bindings, Ada.
k. ISO/IEC 9593.3:1990, Tech. Corrigendum, Programmer's
Hierarchical Interactive Graphics System (PHIGS) Language Bindings,
Ada.
l. ANSI/ISO 9593.4:1991, Information Processing Systems--
Computer Graphics--Programmer's Hierarchical Interactive Graphics
System (PHIGS), Language Bindings, C.
7. Related Documents.
a. Federal Information Resources Management Regulations (FIRMR)
subpart 201.20.303, Standards, and subpart 201.39.1002, Federal
Standards.
b. Federal ADP and Telecommunications Standards Index, U.S.
General Services Administration, Information Resources Management
Service, (updated periodically).
c. NIST, Validated Products List: Programming Languages,
Database Language SQL, Graphics, GOSIP, POSIX, Security, Published
quarterly and available by subscription from the National Technical
Information Service (NTIS), U.S. Department of Commerce,
Springfield, VA 22161.
d. FIPS PUB 69-1, Programming Language FORTRAN, adopts ANSI
X3.9-1978/R1989.
e. FIPS PUB 119, Programming Language Ada, adopts ANSI/MIL-STD-
1815A-1983.
f. FIPS PUB 120-1, Graphical Kernel System (GKS), adopts NISI
X3.124-1985.
g. FIPS PUB 128-1, Computer Graphics Metafile (CGM), adopts
ANSI/ISO 8632: 1992.
h. FIPS PUB 160, Programming Language C, adopts ANSI/ISO 9899:
1992.
i. ANSI/ISO 8632: 1992, Information Processing Systems--Computer
Graphics Metafile for the Storage and Transfer of Picture
Description Information (Part 1: Functional Specifications; Part 2:
Character Encoding; Part 3: Binary Encoding; Part 4: Clear Text
Encoding).
j. ISO/IEC 646: 1991, Information Processing--7-Bit Coded
Character Set for Information Interchange.
k. ISO 2022: 1986, Information Processing--ISO 7-Bit and 8-Bit
Coded Character Sets--Code Extension Techniques.
l. ISO 2382/13: 1984, Data Processing--Vocabulary--Part 13:
Computer Graphics.
m. ISO 6093: 1985, Information Processing--Representation of
Numeric Values in Character Strings for Information Interchange.
n. ISO 7942: 1985, Information Processing Systems--Computer
Graphics--Functional Specification of the Graphical Kernel System
(GKS).
o. ISO 7942/Amendment 1: 1991, Computer Graphics--Graphical
Kernel Systems (GKS) Functional Descriptions.
p. ISO 8805: 1988, Information Processing--Computer Graphics--
Graphical Kernel System (GKS-3D) Extensions Functional Description.
8. Objectives. The primary objectives of this standard are:
--to allow very highly interactive graphics application programs
using 2D or 3D hierarchically structured graphics data to be easily
transported between installations. This will reduce costs associated
with the transfer of programs among different computers and graphic
devices, including replacement devices.
--to aid the understanding and use of dynamic hierarchical graphics
methods by application programmers.
--to aid manufacturers of graphics equipment by serving as a
guideline for identifying useful combinations of graphics
capabilities in a device.
--to encourage more effective utilization and management of graphics
application programmers by ensuring that skills acquired on one job
are transportable to other jobs, thereby reducing the cost of
graphics programmer retraining.
--to aid graphics application programmers in understanding and using
graphics methods by specifying well-defined functions and names.
This will avoid the confusion of incompatibility common with
operating systems and programming languages.
9. Applicability. PHIGS is one of the computer graphics
standards (Appendix A discusses the family of computer graphics
standards) provided for use by all Federal departments and agencies.
These graphics standards should be used for all computer graphics
applications and programs that are either developed or acquired for
government use.
9.1 The FIPS for PHIGS is intended for use in computer graphics
applications that are either developed or acquired for government
use. It is specifically designed to meet the performance
requirements of such demanding applications as Computer Aided
Design/Computer Aided Engineering/Computer Aided Manufacturing,
command and control, molecular modelling, simulation and process
control. It emphasizes the support of applications needing a highly
dynamic, highly interactive operator interface and expecting rapid
screen update of complex images to be performed by the display
system. The PHIGS Plus functionality is designed to support graphics
applications requiring lighting and shading, curved lines, curved
and facetted surfaces, and non-indexed color specification.
9.2 The use of this standard is compulsory and binding when one
or more of the following situations exist:
--The graphics application is very highly interactive, or contains
hierarchically structured graphics data, or requires rapid
modification of 2D or 3D graphics data and the relationships among
the data.
--It is anticipated that the life of the graphics program will be
longer than the life of the presently utilized graphics equipment.
--The graphics application or program is under constant review for
updating of the specifications, and changes may result frequently.
--The graphics application is being designed and programmed
centrally for a decentralized system that employs computers of
different makes and models and different graphic devices.
--The graphics program will or might be run on equipment other than
that for which the program is initially written.
--The graphics program is to be understood and maintained by
programmers other than the original ones.
--The graphics program is or is likely to be used by organizations
outside the Federal government (i.e., State and local governments,
and others).
9.3 Nonstandard features of implementations of PHIGS should be
used only when the needed operation or function cannot reasonably be
implemented with the standard features alone. Although nonstandard
features can be very useful, it should be recognized that the use of
these or any other nonstandard elements may make the interchange of
graphics programs and future conversion more difficult and costly.
10. Specifications. American National Standard Programmer's
Hierarchical Interactive Graphics System, ANSI/ISO 9592.1-3:1989 and
ANSI/ISO 9592.1a, 2a, 3a, 4:1992, define the scope of the
specifications, the syntax and semantics of the PHIGS elements and
requirements for conforming implementations. All of these
specifications apply to Federal Government implementations of this
standard.
ANSI/ISO 9592.103:1989 and ANSI/ISO 9592.1a,2a,3a,4:1992 define
a language independent nucleus of a graphics system for integration
into a programming language. Thus, it is embedded in a language
layer obeying the particular conventions of the language. FIPS 153-1
is therefore divided into two parts. Part 1 represents the
functional aspects of PHIGS. Part 1 consists of the following:
(1) Functional description (ANSI/ISO 9592.1:1989) and (ANSI/ISO
9592.1a:1992, Amendment 1)
The functional description of PHIGS provides a set of functions
for the definition, display and modification of 2D or 3D graphical
data. It also provides for the definition, display and manipulation
of geometrically related objects, along with the modification of
graphics data and the relationships between that graphical data.
(2) Archive file format (ANSI/ISO 9592.2:1989) and (ANSI/ISO
9592.2a:1992, Amendment 1)
The archive file provides a file format suitable for the storage
and retrieval of PHIGS structures and structure network definitions.
It allows structure definitions to be stored in an organized way on
a graphical software system. And, facilitates transfer of structure
definitions between different graphical software systems.
(3) Clear-text encoding (ANSI/ISO 9592.3:1989) and (ANSI/ISO
9592.3a:1992, Amendment 1)
The clear-text encoding provides a representation of the archive
file syntax that is easy to type, edit and read. The file is human-
readable (allows editing), human friendly (easy and natural to read)
and machine readable (parsable by software).
(4) Plus Lumiere and Surfaces, PHIGS PLUS (ANSI/ISO 9592.4:1992)
The Programmer's Hierarchical Interactive Graphics System
(PHIGS) Plus Lumiere and Surfaces (PHIGS PLUS) extends the basic
PHIGS functionality by adding facilities for the specification of
curved lines, curved and facetted surfaces, lighting and other
effects such as depth modulation.
Part 2 of FIPS 153-1 consists of the bindings of PHIGS and PHIGS
PLUS functions to actual programming languages, defined in ANSI/ISO
9593:1990. These bindings are developed in cooperation with the
voluntary standards committees of the various languages. The
following bindings currently exist, and form part 2 of FIPS 153-1:
--The FORTRAN Language binding for PHIGS (ANSI/ISO 9593.1:1990);
--The ADA Language binding for PHIGS (ANSI/ISO 9593.3:1990);
--The C Language binding for PHIGS (ANSI/ISO 9593.4:1991).
Subsequent language bindings, including those for PHIGS PLUS,
will be added periodically as they become available. As these
bindings are approved by ANSI, each language binding will become
part of this standard.
11. Implementation. Implementation of this standard involves
four areas of consideration: the effective date, acquisition of
PHIGS software system implementations, interpretations of PHIGS
implementations, and validation of PHIGS implementations.
11.1 Effective Date. This revised standard is effective six (6)
months after approval by the Secretary of Commerce. Requirements for
the use of basic PHIGS functionality (defined in ANSI/ISO 9592.1-
3;1989 and ANSI/ISO 9593.1:1990, 9593.3:1990, 9593.4:1991) are
unchanged and continue in effect. Validation of PHIGS
implementations is required after the effective date in accordance
with section 11.4.
11.2 Acquisition of Implementations. Conformance to FIPS for
PHIGS is required whether PHIGS toolbox packages are developed
internally, acquired as part of an ADP system procurement, acquired
by separate procurement, used under an ADP leasing arrangement, or
specified for use in contracts for programming services. Recommended
terminology for procurement of FIPS for PHIGS is contained in the
U.S. General Services Administration publication Federal ADP &
Telecommunications Standards Index, chapter 4 part 1.
11.3 Interpretation of this FIPS. NIST provides for the
resolution of questions regarding FIPS for PHIGS specifications and
requirements, and issues official interpretations as needed.
Procedures for interpretations are specified in FIPS PUB 29-3. All
questions about the interpretation of FIPS for PHIGS should be
addressed to: Director, Computer Systems Laboratory (CSL), ATTN:
PHIGS Interpretation, National Institute of Standards and
Technology, Gaithersburg, MD 20899, Telephone: (301) 975-3265.
11.4 Validation of PHIGS Implementations. Implementations of
FIPS for PHIGS using either FORTRAN or C bindings shall be validated
in accordance with NIST Computer Systems Laboratory (CSL) validation
procedures for FIPS for PHIGS. Recommended procurement terminology
for validation of FIPS for PHIGS is contained in the U.S. General
Services Administration publication Federal ADP & Telecommunications
Standards Index, Chapter 4 Part 2. This GSA publication provides
terminology for three validation options: Delayed Validation, Prior
Validation Testing and Prior Validation. The agency shall select the
appropriate validation option. The agency is advised to refer to the
NIST publication Validated Products List for information about the
validation status of PHIGS products. This information may be used to
specify validation time frames that are not unduly restrictive of
competition.
The agency shall specify the criteria used to determine whether
a Validation Summary Report (VSR) or Certificate is applicable to
the hardware/software environment of the PHIGS implementation
offered. The criteria for applicability of a VSR or Certificate
should be appropriate to the size and timing of the procurement. A
large procurement may require that the offered version/release of
the PHIGS implementation shall be validated in a specified hardware/
software environment and that the validation shall be conducted with
specified hardware/software features or parameter settings; e.g.,
the sema parameter settings to be used in a performance benchmark.
An agency with a single-license procurement may review the Validated
Products List to determine the applicability of existing VSRs or
Certificates to the agency's hardware/software environment.
PHIGS implementations using either FORTRAN or C bindings shall
be validated using the NIST PHIGS Test Suite, a suite of automated
validation tests for PHIGS implementations. The NIST PHIGS Test
Suite was first released in July 1990 to help users and vendors
determine compliance with FIPS for PHIGS. The most recent version of
the test suite will be used for validating conformance of PHIGS
implementations after the effective date of FIPS PUB 153-1. The
results of validation testing by the PHIGS Testing Service are
published on a quarterly basis in the Validated Products List,
available from the National Technical Information Service (NTIS).
See related documents section.
Each release of the test suite has provided additional language
bindings and test cases to increase the test suite's coverage of
PHIGS functionality. Version 2.1 of the NIST PHIGS Test Suite,
released in April 1994, provides testing for PHIGS implementations
using either the FORTRAN or C language binding. Version 2.1 does not
include tests for the functionality of PHIGS PLUS added by this
revision of FIPS for PHIGS.
A PHIGS Test Suite license includes all of the tests described
above, documentation, and automatic notifications of approved
changes to the PHIGS Test Suite for a six month period. A license
for the most recent version of the PHIGS Test Suite is a necessary
requirement for an organization that desires to be tested by the
NIST PHIGS Testing Service after the effective date of FIPS 153-1.
Current information about the NIST PHIGS Validation Service and
validation procedures for FIPS for PHIGS is available from: National
Institute of Standards and Technology, Computer Systems Laboratory,
Graphics Software Group, Building 225, room A266, Gaithersburg, MD
20899, (302) 975-3265.
12. Waivers. Under certain exceptional circumstances, the heads
of Federal departments and agencies may approve waivers to Federal
Information Processing Standards (FIPS). The head of such agency may
redelegate such authority only to a senior official designated
pursuant to section 3506(b) of Title 44, United States Code.
Waivers shall be granted only when:
a. Compliance with a standard would adversely affect the
accomplishment of the mission of an operator of a Federal computer
system, or
b. Cause a major adverse financial impact on the operator which
is not offset by Governmentwide savings.
Agency heads may act upon a written waiver request containing
the information detailed above. Agency heads may also act without a
written waiver request when they determine that conditions for
meeting the standard cannot be met. Agency heads may approve waivers
only by a written decision which explains the basis upon which the
agency head made the required finding(s). A copy of each such
decision, with procurement sensitive or classified portions clearly
identified, shall be sent to: National Institute of Standards and
Technology; ATTN: FIPS Waiver Decisions, Technology Building, room
B-154; Gaithersburg, MD 20899. In addition notice of each waiver
granted and each delegation of authority to approve waivers shall be
sent promptly to the Committee on Government Operations of the House
of Representatives and the Committee on Governmental Affairs of the
Senate and shall be published promptly in the Federal Register.
When the determination on a waiver applies to the procurement of
equipment and/or services, a notice of the waiver determination must
be published in the Commerce Business Daily as a part of the notice
of solicitation for offers of an acquisition or, if the waiver
determination is made after that notice is published, by amendment
to such notice.
A copy of the waiver, any supporting documents, the document
approving the waiver and any supporting and accompanying documents,
with such deletions as the agency is authorized and decides to make
under 5 U.S.C. Sec. 552(b), shall be part of the procurement
documentation and retained by the agency.
13. Where to Obtain Copies. Copies of this publication are for
sale by the National Technical Information Service, U.S. Department
of Commerce, Springfield, VA 22161. (Sale of the included
specifications document is by arrangement with the American National
Standards Institute.) When ordering, refer to Federal Information
Processing Standards Publication 153-1 (FIPSPUB153-1) and title.
Payment may be made by check, money order, or deposit account.
Appendix A
The Family of Graphics Standards
The following computer graphics standards are now available to
address the needs of government applications in creating, modifying,
manipulating, and exchanging computer-generated pictures:
FIPS PUB 120-1, the Graphical Kernel System (GKS),
which adopts ANSI X3.124-1985;
FIPS PUB 153-1, the Programmer's Hierarchical
Interactive Graphics System (PHIGS), which adopts ANSI/ISO 9592-
1989;
FIPS PUB 128-1, the Computer Graphics Metafile (CGM),
which adopts ANSI/ISO 8632-1992 and
FIPS PUB 177, the Initial Graphics Exchange
Specification (IGES), which adopts ASME/ANSI Y14.24M-1989.
In addition, the Computer Graphics Interface (CGI) has recently
become an International standard, and is expected to be issued as a
FIPs.
These standards fall into two categories: Application
Programmer's Interface (API) standards, and Interoperability
standards. The goal of API standards is to enhance the portability
of graphics programs (and programmers) between installations and
environments. The goal of Interoperability standards is to enable
graphics data to be exchanged successfully between graphics systems
and devices.
Figure 1 is a very simple reference model of a computer graphics
operating environment. The model emphasizes that a graphics
application program interacts with physical devices and human
operators via a computer graphics environment. Figure 1 also shows
that the application may receive information from an external
database.
The output of the graphics program, as shown in Figure 1, is
directed to a virtual graphics device (i.e., Virtual Device
Interface or VDI) rather than directly to a physical device. A
Device Driver provides an interface, implemented in either hardware
or software, for translating virtual device commands to commands
understood by a particular physical device. By substituting one
device driver for another, an application can run on a different
physical device. This device independent is a central concept of
this graphics reference model.
In Figure 1, the API standards reside in the box labelled the
Device Independent Graphics Package. Interoperability standards are
related to the boxes in Figure labelled Metafile, Database and
Virtual Device Interface. Figure 2 depicts the various graphics
standards associated with the general model shown in Figure 1. These
are discussed below.
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Application Programmer's Interface (API) Standards
Standards at the API promote program and programmer portability.
A standard at this level specifies a set of operations on a variety
of graphics objects. An API standard provides for the portability of
applications across a wide range of computer hardware, operating
systems, programming languages, and graphics devices. A program
written to an API standard at one facility in one environment should
be easily transferable to another facility in a different
environment. Facility dependencies should be the major area
requiring modification.
The specific functions supported by a particular API standard
provide certain capabilities. The application programmer, by
identifying the capabilities needed, determines the API better
suited for the application. As shown in Figure 2, there are
currently two graphics API standards, GKS and PHIGS.
GKS provides a functional description of a two-dimensional (2D)
graphics interface. It provides the basic graphics support required
by a wide variety of applications requiring the production of
computer-generated pictures. A procedural language binding of a
functional standard specifies the exact name for each operation, its
parameter sequence, and the data types for the parameters. FORTRAN,
Pascal, Ada and C language bindings are parts of GKS.
GKS is suitable for use in graphics programming applications
that employ a broad spectrum of graphics, from simple passive
graphics output (where pictures are produced solely by output
functions without interaction with an operator) to interactive
applications; and which control a whole range of graphics devices,
including but not limited to vector and raster devices, microfilm
recorders, storage tube displays, refresh displays, and color
displays.'
PHIGS provides for the definition, display, modification, and
manipulation of 2D and 3D graphical data. It provides functionality
to support storage of graphics and application data in a
hierarchical form. Information may be inserted, changed, and deleted
from the hierarchical data storage with the functions provided by
PHIGS. Language binding specifications for PHIGS include FORTRAN, C
and Ada.
PHIGS is specifically designed to meet the performance
requirements of such demanding applications as Computer Aided
Design/Computer Aided Engineering/Computer Aided Manufacturing,
command and control, molecular modeling, simulation and process
control.
Capabilities in PHIGS but not in GKS include: the centralized
hierarchical data storage: the dynamic and responsive nature of
interactions; the addition of a modeling capability; and support for
color models other than Red-Green-Blue (RGB).
Interoperability Standards
Graphics Interoperability standards allow graphical data to be
interchanged between graphics devices. As shown in Figure 2, there
are three graphics interoperability standards, CGM, (future) CGI,
and IGES.
CGM is used for the storage and transfer of picture description
information. It enables pictures to be recorded for long term
storage, and to be exchanged between graphics devices, system, and
installations. As indicated in Figure 2, the storage mechanism for
CGM is in the form of a neutral file formal called a metafile. The
software which creates the metafile is known as a CGM Generator. The
software which reads and displays a CGM metafile is known as an
Interpreter.
CGM specifies a semantic interface that describes 2D graphical
entities using primitives (like polyline, text, and ellipse) and
attributes (like color, line width, interior style, and fonts). CGM
is compatible with the specification of 2D elements in GKS. A data
encoding specifies the exact sequence of bits used to represent each
operation and its parameters. CGM contains three types of data
stream encodings (binary, character, and clear text) to provide the
implementor choices depending on the particular application.
IGES provides a method for representing and storing geometric,
topological, and nongeometric product definition data that is
independent of any one system. Where CGM transfers graphical
pictures, IGES transfers a graphical database which can be processed
to represent a picture. Thus IGES represents more than just purely
graphical data. As Figure 2 indicates, the storage mechanism for
IGES is in the form of a neutral file format that must be translated
by a Preprocessor and Postprocessor for conversion between systems.
IGES permits the compatible exchange of product definition data used
by various computer aided design/computer aided manufacturing (CAD/
CAM) systems.
The future CGI standard is designed to specify the exchange of
information at the Virtual Device Interface. It will provide an
interface between the device independent and device dependent parts
of a graphics system. Since CGI contains information at a virtual
level, it can be used to create a CGM. A CGM can also be output on a
CGI device in a straightforward manner.
[FR Doc. 94-14779 Filed 6-16-94; 8:45 am]
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