williams-et-al-1983-apple-ii-computer-graphics

ForewordThe introduction of the Apple II computer marked a revolution in computers.For the first time there was a fully fu nctional computing machineavailable which was priced affordably for home users. In addition to itspowerfu l data processing capabil ities, APPLESOFT had the first set ofBASIC extensions which allowed the programmer true power and conveniencewhen working with graphics. The six-color high resolution modewith the HCOLOR and HPLOT commands were "state of the art," and theSHAPE construct and associated DRAW, XDRAW, SCALE, and ROTatefunctions were ahead of their time.When I acquired my fi rst Apple, the Low-Res "Little Brick Out" wasconsidered a very good game, and Bob Bishop's "Applevision" demo was,and still is, awe-inspiring. But with literally millions of people seeing andusing the Apple, advances in style and technique came rapidly as programmersand "hackers" accepted and surmounted one challenge after anotherin their attempt to "do it better."The manuals state that only six colors are available on the High-Resscreen, but Sierra On-Line soon developed over 100 colors. It was notsupposed to be possible to put text on the High-Res screen, but doing so isnow commonplace. The power, ingenuity, and persistence of the humanmind has extended the capabil ities of the Apple further than anyone hadimagined possible. Like most of the current software companies, SierraOn-Line was born in long and solitary hours of developing newer, faster,and better methods of producing graphics on the Apple. In writing thisbook, it is my hope to introduce you to those advanced techniques such asByte-Move, animation, and collision detection, as well as the standardApple graphics.With the aid of my co-authors, who are professional teachers in additionto being experts in the field of home computers, I have tried to presentthose ideas in a manner which is clear and understandable, and whichrelies only on a knowledge of BASIC. I hope you find this book enjoyableto read as well as usefu l in your own program development.Ken WilliamsThe author and publisher of this book have used their best efforts inpreparing this book and the programs contained in it. These effortsinclude the development, research, and testing of the theories and programsto determine their effectiveness. The author and publisher makeno warranty of any kind, expressed or implied, with regard to these programsor the documentation contained in this book. The author andpublisher shall not be liable in any event for incidental or consequentialdamages m connection with, or arising out of, the furnishing, performance,or use of these programs.iv