Archimedes Game Maker’s Manual

292 Pages·1992·47.74 MB·English

by  Terry Blunt

A r c h i m e d e s
G a m e
M a k e r ' s
M a n u a l
Terry Blunt
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A r c h i m e d e s G a m e
M a k e r ' s M a n u a l
Terry Blunt
SIGMA PRESS - Wilmsiow, United Kingdom
Copyright ©, T. Blunt, 1992
All Rights Reserved. No part of this publication may be reproduced, stored in
a retrieval system, or transmitted in any form or by any means, electronic,
mechanical, photocopying, recording or othenA/ise, without prior written
permission.
First published in 1992 by
Sigma Press, 1 South Oak Lane, Wilmslow, Cheshire SK9 6AR, England.
British Library Cataioguing in Publication Data
A GIF catalogue record for this book is available from the British Library.
ISBN: 1-85058-241-6
Typesetting and design by
Sigma Hi-Tech Services Ltd
Printed in Malta by
Interprint Ltd.
Distributed by
John Wiley & Sons Ltd., Baffins Lane, Chichester, West Sussex, England.
Acknowledgement of copyright names
Within this book, various proprietary trade names and names protected by
copyright are mentioned for descriptive purposes. Full acknowledgment is
hereby made of all such protection.
P r e f a c e
This book is for those new to the Archimedes, and probably new to games
programming. Of necessity, some knowledge of programming in Basic is
assumed, so with this in mind working with a copy of the BBC Basic Guide
to hand is advisable. For those producing promising games, but needing to
delve deeper into the Archimedes for more advanced work, serious
consideration should be given to the expense of the Programmers'
Reference Manual.
The Acorn Gamemaker's Manual can be separated naturally into two parts.
The first is a guide to planning and design, as well as programming
techniques particularly applicable to games. The second part is three
groups of subsections that concentrate on each loosely defined game type.
As it is impossible to define precisely a game type these days, reading
over several in the same group will probably be necessary. There is a final
chapter devoted to using the Basic assembler to produce useful ARM code
extensions.
The ideas and methods contained here are intended as a guide rather than
a set of absolute rules, so with increasing experience it will be possible to
extend and improve on this work. Also, even the very best programmers
will admit that there's always a different view of a familiar task, so it pays to
look closely at any program listings that come to hand. The ideal solution
to a problem could quite easily be buried deep inside something as remote
from games as a desktop diary program.
Archimedes Game Maker's Manual
Acknowledgements
I would like to thank Minerva Software for their interest and suggestions
while this book was in its early stages, Nick Pelling for some timely help
near the book's completion, and Steve Turnbull for encouragement and
moral support throughout the development of this, the most complex work I
have undertaken to date.
Terry Blunt
C O N T E N T S
1. Introduction 1
1.1 About the Archimedes 1
1.2 The Environment 3
1.3 Programming Techniques 4
1.4 Making Notes 9
2. Early Planning 12
2.1 Finding Ideas 12
2.2 Targeting 13
2.3 Types of Game 14
2.4 Originality 15
2.5 Addictiveness 16
2.6 Desktop Games 17
2.7 Teamwork 17
2.8 Some Dos 18
2.9 Some Don'ts 20
3. More Planning 22
3.1 Identifying Major Stages 22
3.2 Data Structures 24
3.3 Layouts 25
3.3.1 Positioning 26
3.3.2 Proportions 27
3.3.3 Novelties 27
3.4 Preliminary Testing 28
3.5 Time and Memory 28
3.5.1 Improving loops 28
3.5.2 Subroutines 29
3.5.3 Faster printing 29
3.5.4 Arithmetic variations 30
3.5.5 Decision ordering 30
3.5.6 Data 31
3.5.7 Look-up tables 31
3.5.8 Screen handling 31
3.5.9 A last twiddle 32
Archimedes Game Maker's Manual
3.6 Alternative Strategies 32
3.6.1 Flags 33
3.6.2 Simplifying 33
3.6.3 Advance calculations 34
3.6.3 Interleaving 34
3.7 Time Sharing 34
4. Static Graphics 36
4.1 Drawn Pictures 36
4.2 Sprites 40
4.2.1 User sprites 40
4.2.2 Sprite masking 40
4.2.3 Sprite control 40
4.2.4 A sprite example 41
4.3 User Defined Characters 44
4.4 EOF Patterns 48
4.5 Backgrounds 50
4.6 Banked Screens 52
4.7 Clearing Screen Areas 54
4.8 Smartening Up 54
4.9 Fancy Fonts 59
5. Making it Move 63
5.1 Objects 63
5.2 Movement 63
5.3 Animation 70
5.3.1 Colour changing 71
5.3.2 Animating sprites 73
5.4 Collision Detection 75
5.4.1 Coordinate collisions 75
5.4.2 Pixel collisions 79
5.4.3 Cell collisions 81
5.4.4 Pointer collisions 87
5.4.5 Look ahead 88
5.5 Scrolling 90
5.5.1 Hardware scrolling 90
5.5.2 Scrolling in software 93
5.5.3 ARM code scrolling 95
6. More Dimensions 96
6.1 3D 96
6.1.1 Cartoon styles 96
6.1.2 Scaling 97
6.1.3 Perspective 99
6.1.4 Wire-frame drawings 103
6.1.5 Hidden lines 109
6.1.6 Rotation 110
6.1.7 Matrices 110
6.1.8 Universal movement and rotation 112
6.2 Sound 113
6.2.1 Music 113
6.2.2 More voices 118
6.2.3 Voice generator utilitiy 119
7. Arcade Games 140
7.1 Alien Zapping 140
7.1.1 Movement tables 140
7.1.2 Formations 144
7.1.3 Flocking 150
7.2 Rebounds 153
7.2.1 Bounce patterns 154
7.2.2 Baby Breakout 155
7.2.3 Spin 158
7.2.4 Gravity 159
7.3 Platforms 161
7.4 Map Compression 169
7.5 Score Tables 170
8. Role Play 178
8.1 RPGs 178
8.2 Adventures 188
8.2.1 Rooms 188
8.2.2 Locating objects 189
8.2.3 Understanding instructions 190
8.2.4 Finding nouns 194
8.2.5 Puzzles 195
8.3 Combat 196
8.4 Simulators 197
8.4.1 Real world situation 197
8.4.2 Community simulations 200
8.4.3 Graptiical simulations 201
8.4.4 Terrain mapping 202
8.5 Status Saving and Reloading 205
9. Strategy 206
9.1 Algorittims and Rules 206
9.1.1 Regional variations 206
9.1.2 Symmetrical patterns 207
9.2 Recursive Computer Moves 209
9.2.2 Minimaxing 209
9.2.3 Limiting recursion 210
9.2.3 Pruning 210
9.2.4 Fuzzy ttiinking 211
9.3 Weighting Schemes 211
9.3.1 Key moves 211
9.3.2 Randomising 213
9.4 Introducing Othello 213
Archimedes Game Maker's Manual
9.5 Card Games 214
9.5.1 Displaying a hand 215
9.5.2 Patience layout 215
9.5.3 Implementing Patience 216
9.5.4 Shuffling 217
9.6 Tile-based Games 217
9.7 Word Games 218
9.7.1 Binary searching 219
9.7.2 Text compression 219
9.7.3 User dictionaries 222
9.8 Strategy in 3D 223
10. ARM Code 225
10.1 Why Use It? 225
10.2 Fast Object Tables 225
10.3 Direct Screen Manipulation 229
10.4 ARM Sprites 232
10.4.1 Simple sprites 232
10.4.2 Masking 237
10.4.3 ARM collisions 239
10.5 Reflected Images 244
10.6 ARM Scrolling 248
10.7 Some Final Points 253
10.7.1 Random numbers 254
10.7.2 Square roots 255
10.7.3 Fast circles 257
10.7.4 Clipping 260
Appendix A: Some Useful Sprite Calls 262
Appendix B: VDU Variables (Sub-set) 266
Appendix C: Screen Modes for Standard Monitors 267
Appendix D: Plot Codes 268
Appendix E: VDU Commands 270
Index 273