(Generalized) Langton's Ant Automaton.
Langton's ant is a 2D Turing machine. In this version, at each new x,y location the ant reads the byte value and replaces it w/ another, and chooses a new direction (one of 8 possible directions) to move.
Byte replacement and direction values are read from random arrays.
Java, 119 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 | // <applet code="Ant" width=100 height=100>
// <PARAM NAME="refresh" VALUE="60">
// <PARAM NAME="rndPixels" VALUE="100">
// </applet>
// (Generalized) Langton's Ant Automaton
// http://en.wikipedia.org/wiki/Langton%27s_ant
// FB - 201102163
import java.applet.Applet;
import java.awt.*;
import java.awt.image.*;
import java.util.Arrays;
public class Ant extends Applet
{
Image img;
int pix[],mat[];
int red[],green[],blue[];
int w,h;
long ctm;
int rep[],dir[]; // byte replacement and direction arrays
int[] dirx={1,1,0,-1,-1,-1,0,1};
int[] diry={0,1,1,1,0,-1,-1,-1};
int x,y; // location of the ant
int refresh; // refresh period in seconds
int rndPixels; // # of initial random pixels on the screen
private void putPixel(int x,int y,int c)
{
int alpha=255;
pix[w*y+x]=(alpha<<24)|(red[c]<<16)|(green[c]<<8)|blue[c];
mat[w*y+x]=c;
}
public void init()
{
refresh=Integer.parseInt(getParameter("refresh"))*1000;
rndPixels=Integer.parseInt(getParameter("rndPixels"));
w=getSize().width;
h=getSize().height;
pix=new int[w*h];
mat=new int[w*h];
Arrays.fill(pix,2147483647);
// create a color palette (RGBY)
red=new int[256];
green=new int[256];
blue=new int[256];
for(int i=0;i<256;i++)
{
switch((int)(i/64))
{
case 0:
red[i]=(i%64)*3+64;
green[i]=0;
blue[i]=0;
break;
case 1:
red[i]=0;
green[i]=(i%64)*3+64;
blue[i]=0;
break;
case 2:
red[i]=0;
green[i]=0;
blue[i]=(i%64)*3+64;
break;
case 3:
red[i]=(i%64)*3+64;
green[i]=(i%64)*3+64;
blue[i]=0;
break;
}
}
// create byte replacement and direction arrays
rep=new int[256];
dir=new int[256];
for(int i=0;i<256;i++)
{
rep[i]=(int)(Math.random()*256);
dir[i]=(int)(Math.random()*8);
}
// put random pixels onto screen and start the ant from the last one
for(int i=0;i<rndPixels;i++)
{
x=(int)(Math.random()*w);
y=(int)(Math.random()*h);
putPixel(x,y,(int)(Math.random()*256));
}
ctm=System.currentTimeMillis();
}
public void paint(Graphics g)
{
// restart the applet periodically
if((System.currentTimeMillis()-ctm)>=refresh) {init();}
// run the ant 1 step
int c=mat[w*y+x];
putPixel(x,y,rep[c]);
x+=dirx[dir[c]];
y+=diry[dir[c]];
// keep the ant in the screen
if(x<0) x+=w;
if(x>w-1) x-=w;
if(y<0) y+=h;
if(y>h-1) y-=h;
img=createImage(new MemoryImageSource(w,h,pix,0,w));
g.drawImage(img,0,0,this);
repaint();
}
public void update(Graphics g) { paint(g); } // to prevent flickering
}
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