Maya Character Creation

369 Pages·2008·10.876 MB·English

by  Maraffi, Chris

MEL Scripting
a Character Rig in Maya
Chris Maraffi
MEL Scripting a Character Rig in Maya
Chris Maraffi
New Riders
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Copyright ©2009 by New Riders
Senior Editor: Karyn Johnson
Developmental Editor: Judy Walthers von Alten
Production Coordinator: Becky Winter
Proofreader: Elizabeth Welch
Composition: Danielle Foster
Indexer: Valerie Perry
Cover Design: Charlene Charles-Will
Cover Illustration: Chris Maraffi
Technical Editors: Michael Clavan and Ken Norman
Notice of Rights
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form by any means, electronic, mechanical, photocopying, recording, or other-
wise, without the prior written permission of the publisher. For information on
getting permission for reprints and excerpts, contact [email protected].
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The information in this book is distributed on an “As Is” basis, without warranty.
While every precaution has been taken in the preparation of the book, neither
the author nor Peachpit, shall have any liability to any person or entity with re-
spect to any loss or damage caused or alleged to be caused directly or indirectly
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affi liation with the book.
ISBN-13: 978-0-321-38353-2
ISBN-10: 0-321-38353-2
9 8 7 6 5 4 3 2 1
Printed and bound in the United States of America
I dedicate this book to my beautiful wife Morgan for her tireless
support and encouragement through the long process of writing.
My love always and forever…
Acknowledgments
I want to thank all the dedicated professionals that worked on this book, in-
cluding senior editor at Peachpit, Karyn Johnson, and developmental editor,
Judy Walthers von Alten. All their feedback and suggestions were invaluable
and contributed to making this book the best it could be. In addition, I want
to thank all my colleagues at Full Sail University that helped me develop this
material over the years, including the technical editors of this book—course
directors Ken Norman and Mike Clavan—and lab specialists Carlos Breban,
Monica Hyatt, Dan McCrummen, Kelly Wergin, and Shay Goldenberg. Also
a special thanks to course director Ricardo Tobon for generously sharing his
motion capture expertise.
Contents
Introduction ix
CHAPTER 1 Starting to Rig a Character 1
Rigging in Computer Animation . . . . . . . . . . . . . . . . . . .2
The Job of a Rigging Artist . . . . . . . . . . . . . . . . . . . . . .2
Character Rigging in a 3D Production . . . . . . . . . . . . .5
Important Goals for a Rigging Artist . . . . . . . . . . . . . .6
How Digital Rigging Has Evolved . . . . . . . . . . . . . . . .8
Developing Skills . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
About Maya Skeletons . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Preparing to Create Skeletons . . . . . . . . . . . . . . . . . .17
Drawing Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Understanding Joint Orientation . . . . . . . . . . . . . . .22
Fitting and Animating Skeletons . . . . . . . . . . . . . . .24
Setting Joint Tool Options . . . . . . . . . . . . . . . . . . . . .25
Organizing Nodes in the Hypergraph . . . . . . . . . . . .28
Editing Skeletons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Making Basic Skeleton Edits . . . . . . . . . . . . . . . . . . .30
Performing a Test Bind . . . . . . . . . . . . . . . . . . . . . . . . . .34
Introduction to Smooth Binding . . . . . . . . . . . . . . . .34
Introduction to Painting Skin Weights . . . . . . . . . . .37
Exercise 1.1: Creating a Basic FK Biped Rig . . . . . . . . . . .40
CHAPTER 2 Learning to Script in MEL 53
MEL Scripting Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
Starting to Code in Maya . . . . . . . . . . . . . . . . . . . . . .54
Getting Basic Help on Commands . . . . . . . . . . . . . .58
Following Scripting Conventions . . . . . . . . . . . . . . .63
Learning Essential Coding Techniques . . . . . . . . . . .65
vi CONTENTS
Using Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
Saving MEL Code . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
Refi ning Your Scripts . . . . . . . . . . . . . . . . . . . . . . . . . . . .94
Using Conditions and Loops . . . . . . . . . . . . . . . . . . .94
MEL Rigging Essentials . . . . . . . . . . . . . . . . . . . . . .106
Exercise 2.1: Beginning the Biped Rig Scripts . . . . . . . .124
CHAPTER 3 Scripting a Basic IK Biped Rig 141
Creating the Basic Rig Components . . . . . . . . . . . . . . .142
Using IK Skeletons in the Biped Rig . . . . . . . . . . . .142
Exercise 3.1: Examining the Skeleton
Creation Script . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151
Creating Icons . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160
Exercise 3.2: Scripting the Icons for the Biped Rig . . . .163
Building the Basic Biped Rig . . . . . . . . . . . . . . . . . . . . .172
Creating the Rig Hierarchy in the Hypergraph . . . .173
Preparing to Script the Basic Rig Hierarchy . . . . . . .181
Exercise 3.3: Scripting a Basic IK Rig . . . . . . . . . . . . . . .182
CHAPTER 4 Adding Advanced Rig Controls 191
Enhancing the IK Limb Controls . . . . . . . . . . . . . . . . .192
Creating an Advanced Arm Rig . . . . . . . . . . . . . . . .192
Upgrading the Legs and Feet . . . . . . . . . . . . . . . . .208
Exercise 4.1: Examining the Advanced
Limb Scripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .214
Creating Advanced Head and Torso Controls . . . . . . .229
Upgrading the Head and Face Rig . . . . . . . . . . . . . .229
Building an Advanced Torso Rig . . . . . . . . . . . . . . .233
Exercise 4.2: Scripting the Advanced
Head and Torso . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .242
CHAPTER 5 Finishing the IK Biped Rig 255
Creating a Final Bind . . . . . . . . . . . . . . . . . . . . . . . . . .256
Checking the Skin Model . . . . . . . . . . . . . . . . . . . .256
Smooth Binding the Advanced Rig . . . . . . . . . . . . .256
CONTENTS vii
Using Smooth Binding Options . . . . . . . . . . . . . . .258
Editing the Final Bind . . . . . . . . . . . . . . . . . . . . . . . . . .260
Adding Joints as Infl uence Objects . . . . . . . . . . . . .260
Using Geometry as Infl uence Objects . . . . . . . . . .262
Setting Keys to Facilitate Editing Weights . . . . . . . .266
Using the Paint Skin Weights Tool . . . . . . . . . . . . .267
Editing Weights in the Component Editor . . . . . . .269
Editing Weights Using Menu Commands . . . . . . . .270
Using Indirect Deformation Techniques . . . . . . . . . . .271
Binding with a Proxy Skin . . . . . . . . . . . . . . . . . . . .272
Morphing Through a Proxy Head . . . . . . . . . . . . . .274
Exercise 5.1: Scripting Skin Deformations . . . . . . . . . . .281
CHAPTER 6 Scripting an Advanced Character GUI 291
Creating More GUI Controls . . . . . . . . . . . . . . . . . . . .292
Reviewing Basic Controls in the Setup GUI . . . . . .292
Using Alignment Flags on a Control Group . . . . . .293
Adding a Window Menu . . . . . . . . . . . . . . . . . . . . .293
Incorporating Custom Images . . . . . . . . . . . . . . . . .294
Creating Slider Controls . . . . . . . . . . . . . . . . . . . . .295
Designing a Character GUI . . . . . . . . . . . . . . . . . . . . . .299
Working with Layouts . . . . . . . . . . . . . . . . . . . . . . . . . .300
Parenting Basic Layouts . . . . . . . . . . . . . . . . . . . . . .300
Using Intermediate Layouts . . . . . . . . . . . . . . . . . . .303
Designing an Advanced GUI. . . . . . . . . . . . . . . . . . . . .308
Nesting Intermediate Layouts . . . . . . . . . . . . . . . . .308
Running Script Jobs . . . . . . . . . . . . . . . . . . . . . . . . .310
Exercise 6.1: Scripting the Advanced
Character GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .312
Index 333
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Introduction
This introduction provides an overview of what this book offers to the in-
termediate Maya user, and gives you some information on how this book is
unique in method and approach to Maya Embedded Language (MEL) scripting.
Here you’ll fi nd a brief summary of each chapter, and details on how to down-
load and use the book fi les.
Who Should Read This Book
This book is intended for intermediate Maya users who are interested in us-
ing MEL scripting to enhance the 3D production process in Maya, especially
for character rigging. The reader should have a basic understanding of how to
navigate in the Maya interface, as well as how to perform basic tasks, such as
opening and saving fi les, and manipulating objects in the 3D views. If you’re
a new Maya user, it is recommended that you fi rst complete the basic tutorials
that come with the Maya software before starting the exercises in this book.
Why This Book?
The unique approach of this book is to teach scripting with a character rig-
ging focus. While the MEL coding techniques shown here can be applied to
any technical task in Maya, all the specifi c examples are targeted for rigging
a biped character. There are other more general MEL books on the market, as
well as rigging books that cover some MEL, but none matches the degree and
focus presented here. Going through the exercises in this book will take you to
an advanced level of coding, while also giving you a deeper understanding of
character rigging than you can get by working solely in the Maya interface.
How This Book Is Organized
Throughout this book, you will fi rst learn each major rigging task in the Maya
interface, and then learn how to effi ciently code the same task using MEL. In
the interface this process will involve learning how to create skeletons and
icons, parent nodes into a hierarchy, connect and constrain channels, and de-