Design of computer animation languages

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DESIGN OF

COMPUTER ANIMATION

LANGUAGES

Terry Thoke Trout, BSCS

A Thesis For Master of Science

Department Of Computer Science

University of Adelaide

January 1990 BY

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ABSTRACT DECLARATION

ACKNOWLEDGMENTS

CHAPTER

1: INTRODUCTION

1..1

Inroduction

1.2 Descriptions of the Four Animation Languages 1.2.1 GRAMPS

1.2.2 ASAS 1.2.3

Dial

1.2.4 SCEFO 1.3 Thesis Format

CHAPTE,R

2: BACKGROUND

OF

ANIMATION

SYSTEMS

2.1

Introduction

2.2

Objens

2.2.I

ObjectTypes

2.2.2

Object Transformations

2

.3

Frame to Frame InterPolation

2.4

Scripts

2.5

Displaying Individual Animation ^Frames

2.6

InputMethods

2.7

Control

2.8

Creating ^anAnimation Sequence Quickly.andEasily

2.9

Programming Language Vèrsus Menu Driven System CHAPTER

3: DATA

^STRUCTURES

3.1

Introduction

3.2

Data Structure Primitives and Constructors

3.3

Operators

3.4 D^taType

Checking ^andCoercion

3.5

GRAMPS

.1

Data Structure Primitives

.2

Data Structure Constructors

.3

Instantiating Objects

.4

Operations-on Objects ^andInterpolation

.5

Values

3.6

^ASAS

3.6.1

3.6.2

Data Structure Constructors

3.6.3

PredefinedData

3.6.4

Variables

3.6.5

Operators

3.6.5.

1

^Local^OPerators

3.6.5.2

^Global^Operators

3.6.5.3

Other Operators

3.7 DIAL

3.7.1

Data Stucture Primitives

3.7

.1.1

Contents

of

a Surface Procedure 3.7

.I.2

Instantiating Objects

3.7.2

Operators

5

6 7

I

9 9 10 10 11

t2 t4 t4

L4 15 16

t7 t7

18 18 T9 20

3.5 3.5 3.5 3.5 3.5

2l

2T 22 22 22 23 23 24 26 27 28 28 28 29 30 30

3r 3l

32 32 32 32 33 33 34

1

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Table of Contents

3.7.2.1

Operations on Objects 3.7

.2.2

The "Change" O¡lerator

3.7.2.3

Other Operators

3.7.3

Type Checking

3.8

SCEFO

2

Data Stn¡cture Object TemPlate Instantiating Objects

s

Coercion, TyPe Checking CHAPTER

4: CONTROL

^STRUCTURES

4.1

Introduction

4.2

Selection

4.3

Iteration

4.4

Interpolation

4.5

Procedure and Macro Control Structures

4.6

GRAMPS

4.6.1

Selection ^andIteration

4.6.2

Interpolation

4.6.3

Macros

4.7

ASAS

4.7.1

Iteration

4.7.2

Actors

4.7.3

Interpolation

4.7.4

Hierarchies

4.8 DIAL

Applying Operations to Objects Execution Lines

3.8.1

3.8.2

3.8.3 3.8.

3.8.

34 34 35 36 36 36 37 38 38 39 40 40

4l 4l

42 42 42 42 43 43 43 44 45 45 46 46 46 47 48 49 50 51 51 51 52 53 54 54 55 56

57 57 57 57 58 59 59 59 60 60 61 8

8 8 8 8 4.

4.

.1 .2 .3 .4 .5

Syntax Problems with Execution Lines Interpolation Operation ^s

Definite-Iteration Constructs

4.8.6

Procedures

4.9

SCEFO

4.9.1

Applying Operators to Objects 4.9

.2

Interpotating SCEFO Operations

4.9.3

Order of Operations

4.9.4

Loops

4.9.5

Procedures

4.9.6 Invoking

a Procedure

4.9.7

Hierarchies

CHAPTER

5: NAME

^STRUCTURES

5.1

Inuoduction

5.2

Primitive Name Stnrctures

5.3

Binding Times

5.4

Name Structure Constructors - Scope

5.4.1

Static Scope

5.4.2

Dynamic Scope

5.5

^Parameters

5.6

^GRAMPS

5.6.1

Primitive Name Sffuctures

5.6.2

Memory is Dynamically Allocated

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5.6.3

Name Structure Constructors 61

5

.6.4

Passing Parameters

5.7

ASAS

5.7.1

Names Have Dynamic Scopes

5.7.1.1

Global Name-Binding Functions

5.7.1.2

Passing P¿¡rameters

5.3.1.3 IÆalVariables

5.7.1.4

^Moreon Scope

5.7.2

Actors

5.7

.2.1

Communication Between Actors

5.7.2.2

Scope Barriers Can be Bypassed

5.7.3

Other Functions For Binding Names

5.7.4

Dynamic Global Bindings areDangerous

5.8 DIAL

5.8.1

Primitive Name Structures

5.8.2

Binding Times

5.8.3

Name Structure Constructors 5.8.3.

1

Surface-Dehnition Procedure

5.8.3.2

"Subscript"

5.8.3.3 Block

Structure of a Script

5.8.3.4

Scope

Allows

Transforming Unnamed Objects

5.8.3.5

Reference Environments are

Disjoint 5.9

SCEFO

.1

Primitive Name Stnrctures

.2

Simple Variables

.3 hop

Variables

.4

Names are Bound to Primitive Data When Created

.5

Binding Time

.6

Names Must Be Unique

5.9.7

Type and Value Bindings

5.9.8

Name Structure Constructors

5.9.9

^Scope^{of Fields}

61 62 62 62 63 63 64

&

65 66 66 66 67 67 67 68 68 68 68 69 70 70

7I

7L

7l

72 72 73 73 5.9

5.9 5.9 5.9 5.9 5.9

78 78 79 79 80 80 80 80 81 81 81 82 83 85 85 87 87 87 87 88 89 75 75 76 CHAPTER

6:

^DESIGN^{OF APE -}

ANIMATON PROGRAMMING ENVIRONMENT

6.1

Introduction

6.2

Design Method

6.3

Ape System

6.4

Commenting Scripts

6.5

Data Structures

6.5.1

6.5.1.1 "Models"

6.5. ^1.^1.

1

Predefined Model Figures 6.5. ^1.

1.2

User-defined Models

6.5.L.2

Instantiation

6.5.1.3

Group Data Structure Constructor

6.5.2

Operators

6.5.2.1 IÆal

Transformation Operators

6.5.2.2

Global Transformation Operators

6.5.2.3

Other Operators

6.5.2.4

^TypeChecking and Coercion

6.6

Control Structures

6.6.1

Iteration and Interpolation 6.6.

1.

Action Definition

6.6.1.2

^Schedule

6.6.1.2.1

Automatic Schedule

Filler

(5)

Table of Contents

6.6.1.2.2

Grouping Schedules

6.6.1.2.3

Breaking Journals

6.6.2

Other Definite Iteration Constructs

6.6.3

Conditionals

6.6.3.1

Charting Execution of Conditionals

6.6.3.2

^RepeatingConditionals 6.

6.4

Indefinite Iteration

6.6.5

Control

Sfucture

Constructors

6.6.5.1

Procedures and Functions 98

6.6.5.2

^Actors

6.7

Name Structures

4 91 92 93 94 95 96 97 98 98

Primitives

Dynamic Memory Management Name Structure Constructors

3.1

^Scope^Defined^{by Script}Block-Structure

3.2

^ScopeDefined by Control Stmctures

3.3

Parameter Passing

3.4

^Scope^Definedby Data Structures CHAPTER

7: CONCLUSION

7.1

The Design In Retrospect

7.2

FinalRemarks

BIBLIOGRAPHY

6.7.1

6.7.2

6.7.3 6.7.

6.7.

99 100 100 101 101 101

r02 ro2

103

104

r04 t04

105

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This

thesis analyzes

four

existing animation languages that are quite diverse

in

their designs:

GRAMPS, ASAS (Actor/Scriptor Animation System), Dial (Diagrammatic Animation Language), and SCEFO

^(SCEne

FOrmat language for describing

scenes

in the Brown University Animation

Generation

System).

The analysis

is

performed using measurements designed

from

computer graphics concepts, animation requirements, and aspects and design

principles of

programming

languages. In particular,

the data structures

(primitive

graphics objects),

control

sffuctures and name structures aspects

of

the

four

languages are thoroughly examined, as

well

as those design

principles, slightly

adapted

to computer

^graphicsand animation,

found to exist in

good programming

languages.

Other

important

aspects

of

the languages are discussed, such as how an animation sequence is represented, how any particular frame

of

a sequence

may

be viewed at any

time,

and

how user-friendly

^yet

controllable

^the languages

are. \Morking with

the

findings from this

analysis a

new

animation language is designed and

partially

implemented, incorporating the most positive parts

of

each

of

the

four

languages studied and adding other useful features.

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DECLARATION

This thesis contains no material which has been accepted

for

the award

of

any other degree

or

diploma

in

any

University. To

the best

of my knowledge

and

belief,

the thesis contains ^no material previousþ published or written by another petson, except where due reference is made in the text of the thesis.

I

consent to the thesis being made available

for

photocopying and loan

if

applicable

if

accepted for the award of the degree.

Terry

Trout

January 1990

6

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I

am indebted

to my

supervisor,

Dr. Marc

Berger,

for his

guidance and

support. I

am also

grateful to Dr. Chris Marlin

and

Dr. Dave Bover for their help in the early

stages

of my

resea¡ch.

This research was supported in part by an Adelaide University Research Grant.

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