Revisiting the Dragon Curve

A few days ago I published code to draw the Heighway Dragon Curve. Here's a variation that's 3 lines shorter and plots the curve in 655360 cycles. The pMARS command line is pmarsv -s 90000 -c 1000000.

;redcode-fractal
;name Dragon Curve 2
;author John Metcalf

        width  equ 315
        stack  equ dragon+100
        plot   equ direct+width+1
        first  equ 80*width+50

        mov    #first,   plot
dragon  mov.ab count,    <plot
test    mov.b  @plot,    #0
        add.ba @plot,    direct
        div    #2,       @plot
        mod    #2,       test
        jmz    test,     test
        mod.a  #4,       direct
direct  add.b  3,        width+1
count   sub.ba #65536,   #1+1
        jmp    dragon,   -width+1

Dragon Curve in Redcode

The Heighway Dragon Curve is fractal line than goes through a series of 90° turns, creating a pattern which fills a 2 dimensional space. The program plots 32768 points in 458741 cycles. The pMARS command line is pmarsv -s 90000 -c 500000.

;redcode-fractal
;name Dragon Curve
;author John Metcalf

        width  equ 315
        stack  equ dragon+100

dragon  mov.x  paira,    <stack
recur   djn    dragon,   #15
        mod.a  #4,       direct
        add.b  *direct,  plot
plot    mov    >recur,   80*width+110
        mov.ba >stack,   ret
ret     jmp    0,        }stack
turn    add.a  @stack,   direct
        mov.x  pairb,    <stack
        jmp    recur

direct  dat    3,        width
paira   dat    turn-ret, -1
        dat    0,        -width
pairb   dat    plot-ret, 1

Four Lines of Redcode

The Sierpinski triangle or gasket is a fractal named after the Polish mathematician Waclaw Sierpinski. Surprisingly the fractal can be generated with just 4 lines of Redcode:

        width  equ 126
        trail  equ (sum-CORESIZE%width)
        start  equ (trail-width+1)

sum     mov    #3,    @3
ptr     mov.b  trail, sum
        add.b  {ptr,  sum
        djn    sum,   #start

The magic incantation for pMARS is pmars -v 132. Alternatively set the width to 128 to view using CoreWin :-)

Fractals in Corewar

In 1997 Anton Marsden organised a Corewar tournament with a difference.  The three rounds challenged players to use Redcode to solve a variety of problems.

In the third round of Anton's Corewar Tournament the challenge was to write a Redcode program to draw a pretty picture.  First place was taken by Ilmari Karonen with a fractal fern.

Here's my own attempt at creating a pretty picture in the core view of pMARS. It's a fractal known as the Koch Curve.

Here's the program, just 18 instructions:

width equ 157

        org    koch

        stack equ count+30

koch:   mov    #2-ptr, >stack
        jmp    count,  }move

        sub.a  #2,     move
        mov    #2-ptr, >stack
        jmp    count

        jmp    return, }move

count:  djn    koch,   #11
        mod.a  #8,     move
        div.a  #2,     move
        add.b  *move,  pos
        mul.a  #2,     move
pos:    add    #1,     koch+71*width/2+16
return: mov.ba <stack, ptr
ptr:    jmp    0,      >count

move:   dat    -1
        dat    -width
        dat    1
        dat    width

Have you tried to write a graphical display in Corewar?