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DATE
August 27, 1992
TITLE
Frequently Asked Questions On IRIS Inventor
KEYWORDS
3-D, 3-D graphics, C++, GL, computer graphics, file format,
interaction, objects, picking, object-oriented
QUESTIONS TABLE OF CONTENTS
Q1 What is IRIS Inventor?
Q2 Is IRIS Inventor replacing GL?
Q3 Is there a performance cost using a software layer on top of GL?
Q4 Is IRIS Inventor a user interface toolkit?
Q5 How is IRIS Inventor related to IRIS Explorer?
Q6 Does Inventor have a Fortran or Ada api?
Q7 Does Inventor require C++?
Q8 What operating systems does Inventor require?
Q9 How can I order Inventor documentation?
Q10 How can I learn IRIS Inventor Programming?
Q11 Will Inventor use OpenGL?
QUESTIONS AND ANSWERS
--------------------------------
Q1 What is IRIS Inventor?
IRIS Inventor is an object-oriented 3-D toolkit offering
a comprehensive solution to interactive graphics programming
problems. It presents a programming model based on a 3-D
scene database that dramatically simplifies graphics
programming. It includes a rich set of objects such as
cubes, polygons, text, materials, cameras, lights, trackballs,
handle boxes, 3-D viewers, and editors that speed up your
programming time and extend your 3-D programming capabilities.
IRIS Inventor:
. introduces a simple event model for 3-D interaction
. defines a standard file format for 3-D data interchange
. provides high performance object picking and rendering
. is window system and platform independent
. supports PostScript printing
. encourages programmers to create new customized objects
. is fun to use
Q2 Is IRIS Inventor replacing IRIS GL?
No. GL will always have its place as a lean and mean
rendering library that provides low-level, immediate-mode
access to the frame buffer. Some applications will
prefer the GL frame buffer model to work. However, if you
are writing 3-D applications that require intensive user
interactivity, a 3-D database, 3-D data exchange, picking,
3-D object printing, or a common "look-and-feel", IRIS
Inventor can save an enormous amount of time.
Q3 Is there a performance cost using a software layer on top of GL?
Sometimes. Note that few GL programs achieve peak graphics
performance. This is because most applications have
natural application overhead, and also because many
programmers lack a thorough understanding of the details
and eccentricities of GL. If you are writing a simple
display-only, immediate-mode GL program, then it
will run faster using straight GL, but not much.
However, if your program has scene traversal,
interactivity, picking, bounding box calculations, and
other object space tasks, then Inventor will perform
better for you. This is because Inventor is specially
tuned to make optimal use of GL on each SGI machine.
Furthermore, Inventor supports render caching which
results in peak GL performance in most cases.
We have found that in many cases, Inventor programs run
FASTER than the original GL program, and that the
programmer productivity increases easily outweigh the
overhead of the toolkit.
Q4 Is IRIS Inventor a user interface toolkit?
Yes and no. IRIS Inventor contains mostly 3-D objects.
There is little in the way of conventional user interface
objects such as buttons, dialogs, and menus. However,
Inventor includes a full-fledged event model, a framework
designed for 2-D or 3-D user interaction, and some manip-
ulator objects for 3-D user interface building. Note that
the IRIS Inventor Xt Component and Utility Library
includes some traditional 2-D user interface widgets.
Q5 How is IRIS Inventor related to IRIS Explorer?
IRIS Explorer is an application creation system and user
environment that provides visualization and analysis
functionality for scientists and engineers. IRIS Inventor
is an object-oriented toolkit for 3-D application
programmers. Explorer's 3-D geometry file format is
Inventor's 3-D file format. Explorer's Render Module was
written using IRIS Inventor, and custom Explorer rendering
modules can be written using Inventor.
Q6 Does Inventor have a Fortran or Ada api?
No.
Q7 Does Inventor require C++?
No. You can use the C api and never see or use C++.
Q8 What operating systems does Inventor require?
IRIS Inventor 1.0 and 1.0.1 requires Irix 4.0.1 or greater.
Q9 How can I order Inventor software and/or documentation?
Call your local SGI sales representative or
1-800-800-4SGI to order products:
SC-Inventor-1.0.1 (Software on a CD, Prog. Guides)
ST-Inventor-1.0.1 (Software-only on 1/4" mag tape)
M4-Inventor-1.0.1 (Programming Guide Vols. 1 and 2)
Q10 How can I learn IRIS Inventor Programming?
SGI Technical Education offers a week-long course in IRIS Inventor
Programming. Through extensive hands-on exercises, students learn
to write graphics applications using a library of objects that can
be reused, customized, and extended to meet new needs.
Call 1-800-800-4SGI to sign up.
Topics Covered:
C++ Introduction
Object Oriented Programming
Inventor Database Library
Scene Graphs
Shapes
Texture Mapping
Text - 2D and 3D
Actions applied to Scene Graphs
Printing from Inventor
Interaction Library in Inventor
Interaction model
Manipulators
Components Library for reusable modules
Node Kits to build custom groups of objects
Prerequisties:
C Programming Experience
Basic Unix and editor experience with vi or emacs
Q11 Will Inventor use OpenGL?
IRIS Inventor 2.0 (due out Q3-Q4 CY`93) will use OpenGL.
--
Gavin Bell <gavin@krypton.asd.sgi.com>