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

136 APPLE II COMPUTER GRAPHICSA byte-move shape can be thought of as being pre-defi ned and predrawnsomeplace in the computer' s memor.. Plotting a byte-move shapeis a matter of moving the pre-drawn figure into the screen memory area,just as you might use pre-printed rub-on transfe rs for lettering. In this way,a byte-move shape saves time since it does not have to be regeneratedeach time it is used, but has only to be moved from another locationprefabgraphics.We are getting ahead of ourselves. Listing 12-1 gives a short example ofanimation using the byte-move process. Type it in and try it. You may omitthe REM statements if you wish.10 REM INITIALIZE Y20 REM COORDINATES30 REM40 Y1% = 1:Y2% = 2 :Y3% = 3 :Y4%Y5% = 5 : Y6% = 6: Y7% = 750 REM60 REM READ DATA FOR FIGURE70 REM ,80 FOR I = 1 TO 4: REM 4 FRAMES90 FOR J = 1 TO 7: REM 7 BYTES PERFRAME100 READ V%(I,J)110 NEXT J,I120 REM130 REM INITIALIZE ADDRESSES140 REM OF Y COORDINATES150 REM160 Y%(1)Y%(4)Y%(7)170 HGR180 REM8192 :Y%(2) = 9216 :Y%(3) = 10240 :11264 :Y%(5) = 12288 :Y%(6) = 13312 :14336190 REM POKE THE FOUR FRAMES200 REM210 FOR I = 1 TO 4220 POKE Y% (Y1%) , V% (I,1) :POKE Y% (Y7%) , V% (I, 7)230 POKE Y%(Y2%) , V% (I,2) :POKE Y%(Y6%) ,V%(I,6)240 POKE Y%(Y3%),V%(I,3) :POKE Y%(Y5%) , V% (I,5) :POKE Y%(Y4%) , V% (I,4)250 NEXT260 GOTO 210 : REM START AGAIN270 REM280 REM DATA FOR THE FOUR FRAMES4: