demo_04_sprites1.bas

   10 REM ******************************
   20 REM *        AGON LIGHT 2        *
   30 REM *          DEMO 04           *
   40 REM *      BBC BASIC MODE 8      *
   50 REM *       SPRITES PART 1       *
   60 REM *    THANKS EIGHTBITSWIDE    *
   70 REM *      BY STEVE LOVEJOY      *
   80 REM ******************************
   90 REM USING VDU DOCUMENTAITION FROM:
  100 REM http://agonconsole8.github.io/agon-docs/VDP.html.
  110 :
  120 MB%=&40000 : REM MEMORY BANK &40000.
  130 DIM graphics 1024 : REM ARRAY.
  140 :
  150 REM LOAD SPRITE TO MEMORY.
  160 REM THE PATH BELOW NEEDS TO POINT TO YOUR .rgb IMAGE FILE ON YOUR SDCARD.
  170 PROC_LOAD_SPRITE("/B/Images/80A.rgb",0,16,16) : REM CALL PROC_LOAD_SPRITE WITH SPRITE (n,w,h).
  180 MODE 8 : REM SET SCREEN MODE.
  190 :
 1000 REM SET UP A SPRITE.
 1100 VDU 23,27,4,0 : REM SELECT SPRITE n (equating to buffer ID numbered 64000+n).
 1110 VDU 23,27,5   : REM CLEAR FRAMES FOR CURRENT SPRITE.
 1120 VDU 23,27,6,0 : REM ADD BITMAP n AS FRAME n OF SPRITE.
 1140 VDU 23,27,11  : REM SHOW THE CURRENT SPRITE.
 1150 VDU 23,27,7,1 : REM ACTIVATE n SPRITES (amount).
 1180 :
 1190 REM MOVE THE SPRITE * GAME LOOP.
 1200 FOR X = 1 TO 200
 1220   VDU 23,27,13,X;X;  : REM MOVE CURRENT SPRITE TO POS X,Y (created by X loop).
 1221   VDU 23,27,15       : REM UPDATE THE SPRITES IN THE GPU.
 1230   FOR C = 1 TO 500 : NEXT C  : REM SMALL DELAY.
 1240 NEXT X
 1260 STOP
 1270 :
 1280 REM LOAD BITMAP IMAGE INTO VDP RAM.
 1290 REM F$ - FILENAME/PATH OF BITMAP FROM LINE .
 1300 DEF PROC_LOAD_SPRITE(F$,N%,W%,H%) : REM ** PROC_LOAD_SPRITE **
 1310 OSCLI("LOAD " + F$ + " " + STR$(MB%+graphics)) : REM SYSTEM CALL.
 1320 VDU 23,27,0,N% : REM SELECT BITMAP n (equating to buffer ID numbered 64000+n).
 1330 VDU 23,27,1,W%;H%; : REM LOAD COLOUR BITMAP DATA INTO CURRENT BITMAP.
 1340 FOR I%=0 TO (W%*H%*3)-1 STEP 3 : REM LOOP 16x16x3 EACH PIXEL R,G,B.
 1350   r% = ?(graphics+I%+0) : REM VOODOO HAPPENS HERE.
 1360   g% = ?(graphics+I%+1) : REM CAN ANYONE EXPLAIN.
 1370   b% = ?(graphics+I%+2) : REM AS I HAVE 0 IDEA.
 1380   a% = r% OR g% OR b%
 1390   VDU r%, g%, b%, a%
 1400 NEXT
 1410 ENDPROC : REM END PROC_LOAD_SPRITE.