Commodore Amiga - Page 9

Chapter 4 SPRITE HARDWARE ................................................................................. 91
Introduction ............................................................................................................................. 91
ABOUT THIS ClIAPTER ............................................................................................ 92
Forming a Sprite ................................................................................................................. 92
SCREEN POSITION ...................................................................................................... 92
SIZE OF SPRITES .......................................................................................................... 95
SlIAPE
OF SPRITES ..................................................................................................... 95
SPRITE COLOR
.............................................................................................................. 96
DESIGNING A SPRITE
............................................................................................... 98
BUILDING THE DATA STRUCTURE .................................................................. 99
Displaying a Sprite ............................................................................................................ 104
SELECTING A DMA CHANNEL AND SETTING THE
POINTERS
......................................................................................................................... 105
RESETTING THE ADDRESS POINTERS .......................................................... 106
SPRITE DISPLAY EXAMPLE .................................................................................. 106
Moving a Sprite .................................................................................................................... 108
Creating Additional Sprites ........................................................................................ 110
Reusing Sprite DMA Channels ................................................................................. 111
Overlapped Sprites ............................................................................................................ 114
Attached Sprites ...................................................................................................... ;........... 116
Manual Mode ......................................................................................................................... 119
Sprite Hardware Details ................................................................................................. 120
. Summary of Sprite Registers ..................................................................................... 124
POINTERS ......................................................................................................................... 124
CONTROL REGISTERS ............................................................................................. 125
DATA REGISTERS ........................................................................................................ 126
Summary of Sprite Color Registers ...................................................................... 127
Chapter 5 AUDIO HARDWARE ................................................................................... 131
Introduction ............................................................................................................................. 131
INTRODUCING SOUND GENERATION ........................................................... 132
THE AMIGA SOUND HARDWARE ....................................................................... 135
Forming and Playing a Sound .................................................................................. 136
DECIDING WHICH CHANNEL TO USE ............................................................ 136
CREATING THE WAVEFORM DATA ................................................................ 137
TELLING THE SYSTEM ABOUT THE DATA ................................................ 138
SELECTING THE VOLUME ..................................................................................... 139
SELECTING THE DATA OUTPUT RATE ........................................................ 140
PLAYING THE WAVEFORM ................................................................................... 143
STOPPING THE AUDIO DMA ................................................................................ 144
SUMMARY .... ,.................................................................................................................... 145
EXAMPLE .......................................................................................................................... 145
Producing Complex Sounds ........................................................................................ 147
JOINING TONES ........................................................................................................... 147
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