1-- life.lua
2-- original by Dave Bollinger <DBollinger@compuserve.com> posted to lua-l
3-- modified to use ANSI terminal escape sequences
4-- modified to use for instead of while
5
6local write=io.write
7
8ALIVE="�"	DEAD="�"
9ALIVE="O"	DEAD="-"
10
11function delay() -- NOTE: SYSTEM-DEPENDENT, adjust as necessary
12  for i=1,10000 do end
13  -- local i=os.clock()+1 while(os.clock()<i) do end
14end
15
16function ARRAY2D(w,h)
17  local t = {w=w,h=h}
18  for y=1,h do
19    t[y] = {}
20    for x=1,w do
21      t[y][x]=0
22    end
23  end
24  return t
25end
26
27_CELLS = {}
28
29-- give birth to a "shape" within the cell array
30function _CELLS:spawn(shape,left,top)
31  for y=0,shape.h-1 do
32    for x=0,shape.w-1 do
33      self[top+y][left+x] = shape[y*shape.w+x+1]
34    end
35  end
36end
37
38-- run the CA and produce the next generation
39function _CELLS:evolve(next)
40  local ym1,y,yp1,yi=self.h-1,self.h,1,self.h
41  while yi > 0 do
42    local xm1,x,xp1,xi=self.w-1,self.w,1,self.w
43    while xi > 0 do
44      local sum = self[ym1][xm1] + self[ym1][x] + self[ym1][xp1] +
45                  self[y][xm1] + self[y][xp1] +
46                  self[yp1][xm1] + self[yp1][x] + self[yp1][xp1]
47      next[y][x] = ((sum==2) and self[y][x]) or ((sum==3) and 1) or 0
48      xm1,x,xp1,xi = x,xp1,xp1+1,xi-1
49    end
50    ym1,y,yp1,yi = y,yp1,yp1+1,yi-1
51  end
52end
53
54-- output the array to screen
55function _CELLS:draw()
56  local out="" -- accumulate to reduce flicker
57  for y=1,self.h do
58   for x=1,self.w do
59      out=out..(((self[y][x]>0) and ALIVE) or DEAD)
60    end
61    out=out.."\n"
62  end
63  write(out)
64end
65
66-- constructor
67function CELLS(w,h)
68  local c = ARRAY2D(w,h)
69  c.spawn = _CELLS.spawn
70  c.evolve = _CELLS.evolve
71  c.draw = _CELLS.draw
72  return c
73end
74
75--
76-- shapes suitable for use with spawn() above
77--
78HEART = { 1,0,1,1,0,1,1,1,1; w=3,h=3 }
79GLIDER = { 0,0,1,1,0,1,0,1,1; w=3,h=3 }
80EXPLODE = { 0,1,0,1,1,1,1,0,1,0,1,0; w=3,h=4 }
81FISH = { 0,1,1,1,1,1,0,0,0,1,0,0,0,0,1,1,0,0,1,0; w=5,h=4 }
82BUTTERFLY = { 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 }
83
84-- the main routine
85function LIFE(w,h)
86  -- create two arrays
87  local thisgen = CELLS(w,h)
88  local nextgen = CELLS(w,h)
89
90  -- create some life
91  -- about 1000 generations of fun, then a glider steady-state
92  thisgen:spawn(GLIDER,5,4)
93  thisgen:spawn(EXPLODE,25,10)
94  thisgen:spawn(FISH,4,12)
95
96  -- run until break
97  local gen=1
98  write("\027[2J")	-- ANSI clear screen
99  while 1 do
100    thisgen:evolve(nextgen)
101    thisgen,nextgen = nextgen,thisgen
102    write("\027[H")	-- ANSI home cursor
103    thisgen:draw()
104    write("Life - generation ",gen,"\n")
105    gen=gen+1
106    if gen>2000 then break end
107    --delay()		-- no delay
108  end
109end
110
111LIFE(40,20)
112