'===========================================================================
' Subject: JUPITER BACKGROUND                Date: 12-28-96 (15:59)       
' Author:  Mark Warner                       Code: QB, QBasic, PDS        
' Origin:  devilboy@cyberhall.com          Packet: GRAPHICS.ABC
'===========================================================================
'OsCiLlOsCoPe with spiffy bg
'1996 RSSoft
'devilboy@cyberhall.com
'Written on a P166+ w/GoldStar GCDR-540B x4 cdrom drive, sbawe32 card
'
'I didn't think qbasic was capable of the speed required to do this.
'Then I ran across the asm code to do it, ported it to qb, and whaddya know,
'it is fast enough.  There's not much to it, only a tenny bit of code.
'Just peeking, poking and port inputs...That's it.
'NEW Jupiter Looking Background thing, courtesy of \Hack\ on #qbasic

DIM lin(0 TO 319) AS DOUBLE
DIM saved(0 TO 319) AS DOUBLE
COMMON SHARED dat AS INTEGER, j AS LONG

StartUp:
DEF SEG = &HA000
RANDOMIZE TIMER
SCREEN 13
FOR i = 0 TO 255                'set the palette to black while
        OUT &H3C9, 0            'the screen draws
        OUT &H3C9, 0
        OUT &H3C9, 0
NEXT i
j = 0

DrawBG:
c = 1: p = 1: x = 160: y = 100: s = 100
DO
        c = c + 1: p = p + 1
        IF c = 245 THEN c = 1
        IF p = 64 THEN p = 1
        CIRCLE (x, y), s, c
        PAINT (x, y), c, c
        x = x + 1: y = y - 1: s = s - 2
        IF s < 0 THEN EXIT DO
LOOP

FOR i& = 63999 TO 0 STEP -1     'plot random stars, the fast way...
        IF PEEK(i&) <> 0 THEN GOTO blah
        IF PEEK(i&) = INT(RND * 255) THEN POKE i&, RND * 255
blah: NEXT i&

Main:
DO WHILE r$ = ""                'main loop
OUT &H3C8, 0                    'set palette register to 0
FOR i = 0 TO 255                'set palette to red
        OUT &H3C9, i
        OUT &H3C9, 0
        OUT &H3C9, 0
NEXT i
OUT &H3C8, 0                    'set palette register to 0
FOR i = 0 TO 255                'set palette to green
        OUT &H3C9, 0
        OUT &H3C9, i
        OUT &H3C9, 0
NEXT i
OUT &H3C8, 0                    'set palette register to 0
FOR i = 0 TO 255                'set palette to blue
        OUT &H3C9, 0
        OUT &H3C9, 0
        OUT &H3C9, i
NEXT i
FOR i = 0 TO 319                                'oscilloscope loop
        OUT &H22C, &H20                         'tell SB you want a byte
l1: IF INP(&H22E) = 127 THEN GOTO l1            'if byte null, wait till not null
        dat = ((INP(&H22A) * 1) MOD 50) + 50    'get byte, scale
        lin(i) = PEEK((dat * 320) + i)          'get old pixel
        saved(i) = dat                          'save old pixel to array
        POKE (dat * 320) + i, 250               'poke byte
        IF i <> 319 THEN POKE (saved(i + 1) * 320) + i + 1, lin(i + 1) 'restore old pixel
NEXT i
r$ = INKEY$
LOOP
SCREEN 0
WIDTH 80, 25