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BSAVING AND BLOADING IN QBASIC This tutorial is intended for intermediate programmers who are proficient with standard QBasic commands. 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴 Table of contents (1) so what are BSAVE and BLOAD? (2) making excellent graphics in EGA/VGA 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴 So what are BSAVE and BLOAD? BSAVE and BLOAD are two commands in the QBasic environment to allow you to save graphics created using the method I explained in GRAPHICS.TXT in a file. The file can then be loaded instantaneously from a program, eliminating many of the delays created using the GRAPHICS.TXT method. Both of these commands save part of memory to a file - they don't just have to be used for graphics. This tutorial focuses on graphics. To point BSAVE and BLOAD to the right memory address to start saving from, you must use the DEF SEG statement in this form: DEF SEG = VARSEG(arrayname(0)) arrayname is the name of the array you stored the graphic name in using the GET command. After you are done BSAVEing or BLOADing, use a solitary DEF SEG command to point memory back to where it should be. BSAVE is the next command you will learn in this tutorial. Its basic syntax is: BSAVE "graphic.ext", offset, length "graphic.ext" is the filename of the graphic you want to save. You can have any filename and any extension - for clarity, in my programs I use the .GFX extension, though this is totally arbitrary. length is the size of the array you DIMmed to store the graphic in using the GET command. Be sure to get the EXACT number. The actual file will be seven bytes larger than the length you specify here. offset is the byte address of where to start saving. For the purp- oses of this tutorial, offset will ALWAYS be zero. You can manipulate these commands so as to save more than one graphic in a single file, though I'll probably address this in another tutorial. Now, on to the BLOAD command. Assuming you've already created and saved a graphic using BSAVE, it's time to BLOAD the graphic into a program. It's rather simple, really: DIM arrayname(length) SCREEN screenmode DEF SEG = VARSEG(arrayname(0)) BLOAD "graphic.ext", 0 DEF SEG PUT (0, 0), arrayname Of course, you'll need to stick your arrayname and length into this program along with the name of the file. I have attached with this tut- orial an example of this, BSAVE.BAS, in which I BSAVE and BLOAD a picture of a planet successfully. Look at this and experiment before moving on to the next section. Be sure to use the same SCREEN mode when you BSAVE and when you BLOAD a graphic. For instance, if you BSAVEd a graphic in SCREEN 7, you *must* BLOAD the graphic in SCREEN 7, too. BSAVE files are not screen-mode interchangeable. �-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�-�- Making excellent graphics in EGA/VGA Your best bet for making good graphics in EGA mode is just to practice using the technique I explained in GRAPHICS.TXT. VGA mode graphics can be created using a different method which will yield better results. For VGA graphics, it's best to create sprites in a paint program (for example, CorelDRAW! or Autodesk Animator) and save them in .GIF mode. Use the .GIF loading code attached to this tutorial to load the .GIF in QBasic, then GET it into an array and BSAVE it into QBasic format. An example of this is also attached to the tutorial. 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴 The code above can be modified to whatever your needs.

Program Codes:

'GRAPHIC2.TXT example program 'GRAPHIC2.BAS ' 'The SUBroutine BSAVEExample shows how to BSAVE a picture. 'The rest of the program is an animation. ' 'GIF loading author is unknown. ' ' ' DECLARE SUB BSAVEExample () DECLARE SUB GifLoad (a$) GifLoad "palette.gif": CLOSE DIM m1(6200) DIM mallard(8000) SCREEN 13 speed = 1000 DO FOR i = 1 TO 8 IF x < 95 THEN x = x + 1: ELSE EXIT DO 'IF y < 50 THEN y = y + 1 DEF SEG = VARSEG(m1(0)): BLOAD "b" + LTRIM$(STR$(i)) + ".gfx", 0: DEF SEG PUT (x, y), m1, PSET ERASE m1 FOR j = 1 TO speed: NEXT NEXT LOOP FOR z = 1 TO 3 FOR i = 1 TO 8 DEF SEG = VARSEG(m1(0)): BLOAD "b" + LTRIM$(STR$(i)) + ".gfx", 0: DEF SEG PUT (x, y), m1, PSET ERASE m1 FOR j = 1 TO speed: NEXT NEXT NEXT z speed = speed - (speed \ 1.5) DEF SEG = VARSEG(mallard(0)): BLOAD "mallard.gfx", 0: DEF SEG x2 = 60 y2 = 119 DO FOR i = 1 TO 8 IF y2 >= 80 THEN y2 = y2 - 1: ELSE EXIT DO PUT (x2, y2), mallard, PSET DEF SEG = VARSEG(m1(0)): BLOAD "b" + LTRIM$(STR$(i)) + ".gfx", 0: DEF SEG PUT (x, y), m1, PSET ERASE m1 FOR j = 1 TO speed: NEXT NEXT LOOP speed = speed - (speed \ 2) a = 101 DO FOR i = 1 TO 8 DEF SEG = VARSEG(m1(0)): BLOAD "b" + LTRIM$(STR$(i)) + ".gfx", 0: DEF SEG PUT (x, y), m1, PSET ERASE m1 FOR j = 1 TO speed: NEXT IF s < 60 THEN s = s + 1: PALETTE s + 100, s: s = s + 1: PALETTE s + 100, s: s = s + 1: PALETTE s + 100, s s = s + 1: PALETTE s + 100, s: s = s + 1: PALETTE s + 100, s: s = s + 1: PALETTE s + 100, s END IF IF s = 60 THEN IF ajsaikj = 0 THEN speed = speed * 2: ajsaikj = 1 a = a + .25 IF a >= 160 THEN EXIT DO COLOR INT(a) LOCATE 18, 15 PRINT "presents" END IF NEXT LOOP i = 0 DO WHILE INKEY$ = "" i = i + 1: IF i = 9 THEN i = 1 DEF SEG = VARSEG(m1(0)): BLOAD "b" + LTRIM$(STR$(i)) + ".gfx", 0: DEF SEG PUT (x, y), m1, PSET ERASE m1 FOR j = 1 TO speed: NEXT LOOP DEFINT A-Z DEFSNG A-Z SUB BSAVEExample GifLoad "mallard.gif" DIM mallard(10000) GET (0, 0)-(200, 80), mallard DEF SEG = VARSEG(mallard(0)) BSAVE "mallard.gfx", 0, 10000 DEF SEG END SUB SUB GifLoad (a$) DEFINT A-Z DIM Prefix(4095), Suffix(4095), OutStack(4095), shiftout%(8) DIM Ybase AS LONG, powersof2(11) AS LONG, WorkCode AS LONG FOR a% = 0 TO 7: shiftout%(8 - a%) = 2 ^ a%: NEXT a% FOR a% = 0 TO 11: powersof2(a%) = 2 ^ a%: NEXT a% IF a$ = "" THEN INPUT "GIF file"; a$: IF a$ = "" THEN END IF INSTR(a$, ".") = 0 THEN a$ = a$ + ".gif" OPEN a$ FOR BINARY AS #1 a$ = " ": GET #1, , a$ IF a$ <> "GIF87a" THEN PRINT "Not a GIF87a file.": END GET #1, , TotalX: GET #1, , TotalY: GOSUB GetByte NumColors = 2 ^ ((a% AND 7) + 1): NoPalette = (a% AND 128) = 0 GOSUB GetByte: Background = a% GOSUB GetByte: IF a% <> 0 THEN PRINT "Bad screen descriptor.": END IF NoPalette = 0 THEN P$ = SPACE$(NumColors * 3): GET #1, , P$ DO GOSUB GetByte IF a% = 44 THEN EXIT DO ELSEIF a% <> 33 THEN PRINT "Unknown extension type.": END END IF GOSUB GetByte DO: GOSUB GetByte: a$ = SPACE$(a%): GET #1, , a$: LOOP UNTIL a% = 0 LOOP GET #1, , XStart: GET #1, , YStart: GET #1, , XLength: GET #1, , YLength XEnd = XStart + XLength: YEnd = YStart + YLength: GOSUB GetByte IF a% AND 128 THEN PRINT "Can't handle local colormaps.": END Interlaced = a% AND 64: PassNumber = 0: PassStep = 8 GOSUB GetByte ClearCode = 2 ^ a% EOSCode = ClearCode + 1 FirstCode = ClearCode + 2: NextCode = FirstCode StartCodeSize = a% + 1: CodeSize = StartCodeSize StartMaxCode = 2 ^ (a% + 1) - 1: MaxCode = StartMaxCode BitsIn = 0: BlockSize = 0: BlockPointer = 1 x% = XStart: y% = YStart: Ybase = y% * 320& SCREEN 13: DEF SEG = &HA000 IF NoPalette = 0 THEN OUT &H3C7, 0: OUT &H3C8, 0 FOR a% = 1 TO NumColors * 3: OUT &H3C9, ASC(MID$(P$, a%, 1)) \ 4: NEXT a% END IF LINE (0, 0)-(319, 199), Background, BF DO GOSUB GetCode IF Code <> EOSCode THEN IF Code = ClearCode THEN NextCode = FirstCode CodeSize = StartCodeSize MaxCode = StartMaxCode GOSUB GetCode CurCode = Code: LastCode = Code: LastPixel = Code IF x% < 320 THEN POKE x% + Ybase, LastPixel x% = x% + 1: IF x% = XEnd THEN GOSUB NextScanLine ELSE CurCode = Code: StackPointer = 0 IF Code > NextCode THEN EXIT DO IF Code = NextCode THEN CurCode = LastCode OutStack(StackPointer) = LastPixel StackPointer = StackPointer + 1 END IF DO WHILE CurCode >= FirstCode OutStack(StackPointer) = Suffix(CurCode) StackPointer = StackPointer + 1 CurCode = Prefix(CurCode) LOOP LastPixel = CurCode IF x% < 320 THEN POKE x% + Ybase, LastPixel x% = x% + 1: IF x% = XEnd THEN GOSUB NextScanLine FOR a% = StackPointer - 1 TO 0 STEP -1 IF x% < 320 THEN POKE x% + Ybase, OutStack(a%) x% = x% + 1: IF x% = XEnd THEN GOSUB NextScanLine NEXT a% IF NextCode < 4096 THEN Prefix(NextCode) = LastCode Suffix(NextCode) = LastPixel NextCode = NextCode + 1 IF NextCode > MaxCode AND CodeSize < 12 THEN CodeSize = CodeSize + 1 MaxCode = MaxCode * 2 + 1 END IF END IF LastCode = Code END IF END IF LOOP UNTIL DoneFlag OR Code = EOSCode 'BEEP 'A$ = INPUT$(1) EXIT SUB GetByte: a$ = " ": GET #1, , a$: a% = ASC(a$): RETURN NextScanLine: IF Interlaced THEN y% = y% + PassStep IF y% >= YEnd THEN PassNumber = PassNumber + 1 SELECT CASE PassNumber CASE 1: y% = 4: PassStep = 8 CASE 2: y% = 2: PassStep = 4 CASE 3: y% = 1: PassStep = 2 END SELECT END IF ELSE y% = y% + 1 END IF x% = XStart: Ybase = y% * 320&: DoneFlag = y% > 199 RETURN GetCode: IF BitsIn = 0 THEN GOSUB ReadBufferedByte: LastChar = a%: BitsIn = 8 WorkCode = LastChar \ shiftout%(BitsIn) DO WHILE CodeSize > BitsIn GOSUB ReadBufferedByte: LastChar = a% WorkCode = WorkCode OR LastChar * powersof2(BitsIn) BitsIn = BitsIn + 8 LOOP BitsIn = BitsIn - CodeSize Code = WorkCode AND MaxCode RETURN ReadBufferedByte: IF BlockPointer > BlockSize THEN GOSUB GetByte: BlockSize = a% a$ = SPACE$(BlockSize): GET #1, , a$ BlockPointer = 1 END IF a% = ASC(MID$(a$, BlockPointer, 1)): BlockPointer = BlockPointer + 1 RETURN END SUB