-- life.lua

-- original by Dave Bollinger <DBollinger@compuserve.com> posted to lua-l

-- modified to use ANSI terminal escape sequences

-- modified to use for instead of while

local write=io.write

ALIVE="¥" DEAD="þ"

ALIVE="O" DEAD="-"

function delay() -- NOTE: SYSTEM-DEPENDENT, adjust as necessary

for i=1,10000 do end

-- local i=os.clock()+1 while(os.clock()<i) do end

end

function ARRAY2D(w,h)

local t = {w=w,h=h}

for y=1,h do

t[y] = {}

for x=1,w do

t[y][x]=0

end

end

return t

end

_CELLS = {}

-- give birth to a "shape" within the cell array

function _CELLS:spawn(shape,left,top)

for y=0,shape.h-1 do

for x=0,shape.w-1 do

self[top+y][left+x] = shape[y*shape.w+x+1]

end

end

end

-- run the CA and produce the next generation

function _CELLS:evolve(next)

local ym1,y,yp1,yi=self.h-1,self.h,1,self.h

while yi > 0 do

local xm1,x,xp1,xi=self.w-1,self.w,1,self.w

while xi > 0 do

local sum = self[ym1][xm1] + self[ym1][x] + self[ym1][xp1] +

self[y][xm1] + self[y][xp1] +

self[yp1][xm1] + self[yp1][x] + self[yp1][xp1]

next[y][x] = ((sum==2) and self[y][x]) or ((sum==3) and 1) or 0

xm1,x,xp1,xi = x,xp1,xp1+1,xi-1

end

ym1,y,yp1,yi = y,yp1,yp1+1,yi-1

end

end

-- output the array to screen

function _CELLS:draw()

local out="" -- accumulate to reduce flicker

for y=1,self.h do

for x=1,self.w do

out=out..(((self[y][x]>0) and ALIVE) or DEAD)

end

out=out.."\n"

end

write(out)

end

-- constructor

function CELLS(w,h)

local c = ARRAY2D(w,h)

c.spawn = _CELLS.spawn

c.evolve = _CELLS.evolve

c.draw = _CELLS.draw

return c

end

--

-- shapes suitable for use with spawn() above

--

HEART = { 1,0,1,1,0,1,1,1,1; w=3,h=3 }

GLIDER = { 0,0,1,1,0,1,0,1,1; w=3,h=3 }

EXPLODE = { 0,1,0,1,1,1,1,0,1,0,1,0; w=3,h=4 }

FISH = { 0,1,1,1,1,1,0,0,0,1,0,0,0,0,1,1,0,0,1,0; w=5,h=4 }

BUTTERFLY = { 1,0,0,0,1,0,1,1,1,0,1,0,0,0,1,1,0,1,0,1,1,0,0,0,1; w=5,h=5 }

-- the main routine

function LIFE(w,h)

-- create two arrays

local thisgen = CELLS(w,h)

local nextgen = CELLS(w,h)

-- create some life

-- about 1000 generations of fun, then a glider steady-state

thisgen:spawn(GLIDER,5,4)

thisgen:spawn(EXPLODE,25,10)

thisgen:spawn(FISH,4,12)

-- run until break

local gen=1

write("\027[2J") -- ANSI clear screen

while 1 do

thisgen:evolve(nextgen)

thisgen,nextgen = nextgen,thisgen

write("\027[H") -- ANSI home cursor

thisgen:draw()

write("Life - generation ",gen,"\n")

gen=gen+1

if gen>2000 then break end

--delay() -- no delay

end

end

LIFE(40,20)