Fractals, how to??

[h0ffman]

Was wondering if anyone here every wrote any code to generate a fractal image? I was doing a little research and found this site http://library.thinkquest.org/3493/frames/fractal.html with this basic example in.

CLS
FOR i = 1 TO 300
	FOR j = 1 TO 150
		c1=-2+4*i/300
		c2=2-4*j/300
		x=c1
		y=c2
			FOR n = 1 TO 30
			x1=x*x-y*y+c1
			y1=2*x*y+c2
			r=x1*x1+y1*y1
			IF r > 4 THEN GOTO 1000
			x = x1
			y = y1
			NEXT n
		PSET(i, j)
		PSET(i,300-j)
	1000 NEXT j
NEXT i
END

Just wondered if anyone had any experience with this kinda stuff?

Edit: Thats a Mandelbrot btw.

[Lonewolf10]

No real experience, I have created one before but have no clue how to manipulate the routine to zoom in on a particular area of the fractal. Elena Noveretti had a great website ( www.elena-fractals.it ) full of awesome fractals she created, but the website seems to be down
She was interviewed in issue 24 of Total Amiga, which included a few pictures of the fractals she created along with the basics of creating fractals.

You can find loads of awesome fractal creators here, and I ended up looking at some cool ones created by Jennifer Scotland (Sasqui), which can be found here.


Regards,
Lonewolf10

[Dan]

Elena Noveretti had a great website ( www.elena-fractals.it ) full of awesome fractals she created, but the website seems to be down

Lucky web archive has still a copy of it
http://web.archive.org/web/200302071...a-fractals.it/
but only some of the big pictures are available.

[zardoz]

pick a language, write your code and press go.

My first Mandelbrot generator was written in Spectrum basic. It took about a minute to plot a pixel so I left it on overnight and by the morning my speccy had died :-(

Originally Posted by h0ffman

CLS
FOR i = 1 TO 300
    FOR j = 1 TO 150
        c1=-2+4*i/300
        c2=2-4*j/300
        x=c1
        y=c2

So i and j are your screen or bitmap coordinates - in this case your output will be 300 x 150 pixels
c1 and c2 are the area of the graph that you are plotting. Your x axis is 'real numbers' and your y axis 'imaginary numbers'.
So C1 goes from -2 to +2 in this case
c2 goes from -2 to 0

To zoom in you'd choose different values for C1 & C2

[h0ffman]

Cheers zardoz, will have fire up Devpac now and see how fast I can get this baby to plot.

[victim]

Hi h0ffman !

Here I have a small mandelbrot fractal developed.
It is still not very optimized, but it runs on all Amigas.
The code is very quick and dirty programmed and only for a example.

;******    Date:    19.07.2011    Prog: Mandelbrot-Fractal
;******
;******    Autor:    Victim of Savage

planesize =    44*286
xv    =    -21403
yv    =    -10240
xmax    =    -30352-xv
xmin    =    -xv
ymin    =    22000+yv
ymax    =    yv
deep    =    32
factor    =    1024
xsize    =    352
ysize    =    286
bplanes    =    5

    section    code,code_c
    
start:    movem.l    d0-d7/a0-a6,-(a7)

    lea    $dff000,a6
    move    #$01e0,$96(a6)
    move    #$4000,$9a(a6)
    lea    CopperList,a1
    move.l    a1,$84(a6)
    move    #$8180,$96(a6)

    bsr    InitPlanes    
    bsr    Colors
    bsr    CalcMandel
    
maus:    btst     #6,$bfe001
    bne     maus
end:    move    #$83e0,$dff096
    movem.l    (a7)+,d0-d7/a0-a6
    rts

Colors:    lea        Copcolors,a0
    move    #$0180,d0
    move    #$0000,d1
    moveq    #15,d2
loop:    move    d0,(a0)+
    move    d1,(a0)+
    addq    #2,d0
    add        #$0100,d1
    dbf        d2,loop    
    move    #$0f00,d1        
    moveq    #14,d2
loop2:    move    d0,(a0)+
    addq    #2,d0            
    add        #$0010,d1
    move    d1,(a0)+
    dbf        d2,loop2
    rts
        
InitPlanes:
    lea.l    CopperPlanes,a0
    move.l    plane0,d0
    moveq    #4,d7
Copy2:    move    d0,6(a0)
    swap    d0
    move    d0,2(a0)
    swap    d0
    add.l    #planesize,d0
    addq.l    #8,a0
    dbf        d7,Copy2
    rts

CalcMandel:
    move.l     #xmax-xmin,d0
    move.l     #xsize,d1
    divs     d1,d0
    move     d0,a2
    move.l     #ymax-ymin,d0
    move.l     #ysize,d1
    divs     d1,d0
    move     d0,a3
    move.l     #xmin,d6
    move.l     #ymax,d7    
forz:    sub.l    a1,a1
    btst     #6,$bfe001
    beq     end
forss:    suba.l    a5,a5
fors:    suba.l    a0,a0
    lea        empty(pc),a0
    movem.l    (a0)+,d0-d4
while:    move.l     #factor,d5
    muls     d0,d1
    add.l     d1,d1
    asr.l     #5,d1
    asr.l     #5,d1
    asr.l     #3,d1
    sub.l     d7,d1
    move.l     d2,d0
    sub.l     d3,d0
    sub.l     d6,d0
    move.l     d0,d2
    muls     d2,d2
    asr.l     #5,d2
    asr.l     #5,d2
    asr.l     #3,d2
    move.l     d1,d3
    muls     d3,d3
    asr.l     #5,d3
    asr.l     #5,d3
    asr.l     #3,d3
    addq.l     #1,d4
    cmp     #deep,d4
    bge     weiter1
    asl.l     #5,d5
    sub.l     d3,d5
    sub.l     d2,d5
    bge     while
    bra     weiter2
weiter1:
    moveq     #0,d4
weiter2:
    lea     plane0,a0
    moveq     #bplanes-1,d0
next:    move.l     (a0)+,a6
    asr     #1,d4
    roxl     (a6)
    dbf     d0,next

    add.l     a2,d6
    addq.l     #1,a5
    cmp.l     #15,a5
    ble     fors

    lea     plane0,a0
    moveq     #bplanes-1,d0
next1:    addq.l     #2,(a0)+
    dbf     d0,next1

    addq.l     #1,a1
    cmp.l     #xsize/16-1,a1
    ble     forss
    move.l     #xmin,d6
    sub.l     a3,d7
    addq.l     #1,a4
    cmp.l     #ysize-1,a4
    ble     forz
    rts

empty:    blk.l    5,0
        
    section    copperlist,DATA_c
    
CopperList:    
        dc.l    $01200000,$01220000
        dc.l    $01fc0000
        dc.l    $01020000,$01040000
        dc.l    $01060000
        dc.l    $01080000,$010a0000
CopperPlanes:
        dc.l    $00e00000,$00e20000
        dc.l    $00e40000,$00e60000
        dc.l    $00e80000,$00ea0000
        dc.l    $00ec0000,$00ee0000
        dc.l    $00f00000,$00f20000
        dc.l    $008e1a71,$009037e1
        dc.l    $00920030,$009400d8
        dc.l    $01005200
CopColors:
        blk.l    32        
        dc.l    -2

plane0:    dc.l    PlaneBuffer
    dc.l    PlaneBuffer+planesize
    dc.l    PlaneBuffer+planesize*2
    dc.l    PlaneBuffer+planesize*3
    dc.l    PlaneBuffer+planesize*4

        section Planes,BSS_c

PlaneBuffer:    ds.b    planesize*5

Here is a link to an interview with Elena Novaretti from the year 2006. The interview is very well done and also provides the mathematical foundations of fractal programming.

http://www.savage-crew.de/TA24_ElenaIview_Full.pdf


so long...
victim

Originally Posted by h0ffman

Was wondering if anyone here every wrote any code to generate a fractal image? I was doing a little research and found this site http://library.thinkquest.org/3493/frames/fractal.html with this basic example in.

CLS
FOR i = 1 TO 300
    FOR j = 1 TO 150
        c1=-2+4*i/300
        c2=2-4*j/300
        x=c1
        y=c2
            FOR n = 1 TO 30
            x1=x*x-y*y+c1
            y1=2*x*y+c2
            r=x1*x1+y1*y1
            IF r > 4 THEN GOTO 1000
            x = x1
            y = y1
            NEXT n
        PSET(i, j)
        PSET(i,300-j)
    1000 NEXT j
NEXT i
END

Just wondered if anyone had any experience with this kinda stuff?

Edit: Thats a Mandelbrot btw.

[h0ffman]

Wow, cheers victim, wasn't expecting an assembly example.

[Lonewolf10]

Originally Posted by victim

Here is a link to an interview with Elena Novaretti from the year 2006. The interview is very well done and also provides the mathematical foundations of fractal programming.

http://www.savage-crew.de/TA24_ElenaIview_Full.pdf

That's the interview from Total Amiga I was on about


Regards,
Lonewolf10

[Parsec]

I used to really like playing about with Fractint on my PC, it was a brilliant package and seemed to be thriving, but it's almost disappeared now. Still apparently available though - http://www.nahee.com/spanky/www/fractint/fractint.html