Alice: Easy-to-Learn 3D Scripting for Novices

242 Pages·1999·1.12 MB·English

Chapter 1 –
Alice:
Easy-to-Learn 3D Scripting for Novices
A Dissertation
presented to
the Faculty of the School of Engineering and Applied Science
at the
University of Virginia
In Partial Fulfillment
of the Requirements for the Degree
Doctor of Philosophy (Computer Science)
by
Matthew J Conway
December 1997
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Chapter 1 –
Alice: Easy-to-Learn 3D Scripting for Novices
© 1997 Matthew Conway All Rights Reserved
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Chapter 1 –
Approval Sheet
This dissertation is submitted in partial fulfillment of the
requirements for the degree of
Doctor of Philosophy (Computer Science)
Author
This dissertation has been read and approved by the Examining Committee:
Dissertation Advisor
Committee Chairman
Committee Member
Committee Member
Committee Member
Committee Member
Accepted for the School of Engineering and Applied Science:
Dean Richard W. Miksad
School of Engineering and Applied Science
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Chapter 1 –
Table Of Contents
Chapter 1 Acknowledgements................................................................................................................7
Chapter 2 The Three Stages of Media................................................................................................10
Chapter 3 Executive Overview............................................................................................................20
Chapter 4 Alice System Overview.......................................................................................................26
Chapter 5 System Description.............................................................................................................51
Chapter 6 The Alice Main Loop..........................................................................................................74
Chapter 7 Empirical Evidence.............................................................................................................94
Chapter 8 Traditional APIs for 3D...................................................................................................112
Chapter 9 Objects, Parts and Children.............................................................................................124
Chapter 10 The Death of XYZ............................................................................................................131
Chapter 11 Rotation ........................................................................................................................156
Chapter 12 Sizing and Scaling..............................................................................................................172
Chapter 13 Color, Texture and Visibility...........................................................................................183
Chapter 14 Programming Language Issues........................................................................................194
Chapter 15 Future Work.......................................................................................................................206
Chapter 16 Previous Work...................................................................................................................227
Chapter 17 Conclusions........................................................................................................................234
Chapter 18 References ........................................................................................................................238
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Chapter 1 –
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Chapter 1 –
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Chapter 1 – Acknowledgements
It is easy to work when the soul is at play
Emily Dickinson
Acknowledgements
Alice would not exist but for the tireless efforts of every member of the University
of Virginia User Interface Group. Without the UIgroup, this work and the larger Alice effort
would have been impossible. Past and present members can be found at
http://www.cs.cmu.edu/~stage3/ and through the About option on Alice’s Help menu. I would
also like to extend thanks:
To Randy Pausch, whose insight and guidance shaped this research from the
beginning with a belief that fun is a critical component of any research venture.
To Tommy Burnette, Kevin Christiansen, and Dennis Cosgrove, for their infinite
patience and brilliant insights in constructing the core of the PC/Windows 95 Alice
implementation. They worked extremely hard to respond to the user testing that this work
reflects and their insight in the design process was invaluable.
To Rob DeLine, for his Master’s thesis on the first Alice implementations and his
design of the Alice architecture. Rob’s hand is still evident in Alice, a testimony to his
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Chapter 1 – Acknowledgements
outstanding design skills.
To Rich Gossweiler, Shuichi Koga, Jim Durbin, Chris Long, Steve Miale, and
George Williams for their design, implementation, development and maintenance of the
original (now dormant) Silicon Graphics implementation of the Alice rendering engine,
known in its day as Diver [Gossweiler]. Abandoning that code base for the PC world was a
difficult decision, given Diver’s outstanding stability and flexibility.
To Ken Hinckley and Jeff Pierce, Joe Shochet, and Brian Stearns for their help in the
odious task of documentation writing.
To James “The Man” Patten for his work on the GUI tools he created for the Alice
development environment, those that made it and those that didn’t.
To Kristin Monkatis, Steve Audia, Chris Sturgil, David Staack for their phenomenal
artistic input. Their skill brought a new burst of life at just the right time in the Alice
development process. They helped remind me that what we were working on was in fact
extremely cool. VR researchers forget the content side of the equation at their own peril,
even if what they’re doing is “just research.”
To George Robertson and Microsoft Research for the patience and time they gave
me in finishing this work.
To the Defense Advanced Research Projects Agency (DARPA) for funding this
research.
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Chapter 1 – Acknowledgements
To the members of the UVA CS department for their personal support and their
generous support of the UIGroup, through the years.
To Jeni Willoughby and the teachers, administrators, and students in the Lynchburg
Virginia School Systems for the courage and leadership it took to deploy the beta version of
Alice in their high school.
And finally to Cassi Sendroff, age 11, and her sister, Eireann age 13, for the
wonderful Alice worlds they created and for their perseverance with Alice, especially in the
face of inadequate documentation. Their accomplishments with Alice were wonderful and
surprising, and an unexpected validation of this work.
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Chapter 1 – The Three Stages of Media
The content of any medium is always another medium
Marshall McLuhan

Chapter 1
The Three Stages of Media
The Alice project traces its roots back to early 1991, when the first Virtual Reality
systems were being built at the University of Virginia. Starting with a desire to build new
interaction techniques for immersive, head-tracked Virtual Reality (VR) simulations, we
quickly found that the tools that were available for this work were extremely hard to use for
exploring a new user interface design space. Realizing that this itself was a reasonable
research agenda, we set out to build programming tools that were easier and faster to use,
not just for ourselves but for as many people as we thought reasonably possible. This effort,
though it started with several tentative prototypes under a variety of names1, soon settled
into what is now called the Alice project. We took as our charter the task of making
interactive 3D graphics much more accessible to 19 year old “non-programmer”

1 Alice is the lastest system in a series of prototypes that we built starting in the early 1990s. Previous systems were
named RPVR, Strobe, and Joe. We never had a system named Dave.
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