SCREEN 12
PRINT "Trage-Groei Fractal SloGro"
PRINT "Slow growth fractal"
PRINT "Ref: COMPUTER RECREATONS by A.K.Dewdney,"
PRINT "SCIENTIFIC AMERICAN December 1988"
PRINT "******************************************"
PRINT
PRINT "Druk toets om te stoppen/Press a key to stop"
PRINT "********************************************"

PRINT : PRINT : PRINT : COLOR 10
PRINT "     Credits: guido wuyts 1997"
PRINT : PRINT : PRINT : COLOR 3
PRINT "     -> Toets/Key...": COLOR 15
PLAY "o4l24d"
SLEEP: a$ = INKEY$: a$ = "": COLOR 12
CLS

Init:
n% = 500: DIM mx(n%), my(n%)
x0 = 320: y0 = 240
xx0 = 3: yy0 = 3: xmax = 3: ymax = 3: xmin = 3: ymin = 3
cnt% = 0: mx(cnt%) = x0: my(cnt%) = y0
RANDOMIZE TIMER
dx = 4: dy = 4
LINE (x0 - dx, y0 - dy)-(x0 + dx, y0 + dy), 3, BF

Nieuw:

IF NOT INKEY$ = "" GOTO Einde
x1 = x0: y1 = y0

IF xmin + xmax < ymin + ymax GOTO hor ELSE GOTO vert

hor:

IF xmax < xmin THEN
x = x1 + 2 * dx * (xmax + 1)
         ELSE
x = x1 - 2 * dx * (xmin + 1)
         END IF
y = y1 + 2 * dy * (-ymin + INT(RND * (ymin + ymax)))
GOTO Beeldaf

vert:

IF ymax < ymin THEN
y = y1 + 2 * dy * (ymax + 1)
         ELSE
y = y1 - 2 * dy * (ymin + 1)
         END IF
x = x1 + 2 * dx * (-xmin + INT(RND * (xmin + xmax)))
GOTO Beeldaf

Beeldaf:

LINE (x - dx, y - dy)-(x + dx, y + dy), 3, BF

ChecCont:

FOR tel% = 0 TO cnt%
IF mx(tel%) = x AND my(tel%) = y THEN LINE (x - dx, y - dy)-(x + dx, y + dy), 3, BF: GOTO Beweeg
IF ABS(x - mx(tel%)) = 2 * dx AND my(tel%) = y GOTO Teken
IF ABS(y - my(tel%)) = 2 * dy AND mx(tel%) = x GOTO Teken
NEXT tel%

Beweeg:

sel = RND: x1 = x: y1 = y
IF sel <= .25 THEN x = x - 2 * dx
IF .25 < sel AND sel <= .5 THEN y = y + 2 * dy
IF .5 < sel AND sel <= .75 THEN x = x + 2 * dx
IF .75 < sel THEN y = y - 2 * dy
LINE (x1 - dx, y1 - dy)-(x1 + dx, y1 + dy), 0, BF'Wis                                                     
IF x < x0 - 2 * dx * (xmin + xx0) OR x > x0 + 2 * dx * (xmax + xx0) GOTO Nieuw'Beperk zwerf
IF y < y0 - 2 * dy * (ymin + yy0) OR y > y0 + 2 * dy * (ymax + yy0) GOTO Nieuw
LINE (x - dx, y - dy)-(x + dx, y + dy), , BF 'NieuwPt                 
GOTO ChecCont

Teken:

LINE (x - dx, y - dy)-(x + dx, y + dy), 3, BF'FixGroei
cnt% = cnt% + 1
IF cnt% > n% GOTO Einde
mx(cnt%) = x: my(cnt%) = y
IF x < x0 - 2 * dx * xmin THEN xmin = INT((x0 - x) * .5 / dx)
IF x > x0 + 2 * dx * xmax THEN xmax = INT((x - x0) * .5 / dx)
IF y < y0 - 2 * dy * ymin THEN ymin = INT((y0 - y) * .5 / dy)
IF y > y0 + 2 * dy * ymax THEN ymax = INT((y - y0) * .5 / dy)
GOTO Nieuw

Einde:
BEEP
END