Conway's Game of Life in Lua for the Codea iOS app

gol.lua

Gol = class()

function Gol:init(W, H)
    -- Set the size
    self.columns  = W
    self.rows     = H
    
    -- The varying states of cells
    self._alive    = 1
    self._dead     = 0
    
    -- The game states
    self._paused   = 0
    self._stepping = 1
    
    -- Some public things
    self.matrix    = {}
    
    -- This is a method to set for a draw method
    -- Called for every cell every frame
    self.drawMethod = function(cell) end
    
    -- Create a blank board
    self:create()
end

function Gol:create()
    for r = 1, self.rows do
        table.insert(self.matrix, {})
        for c = 1, self.columns do
            table.insert(self.matrix[r], {})
            self.matrix[r][c] = self._dead
        end
    end
end

function Gol:clear()
    for r = 1, self.rows do
        for c = 1, self.columns do
            self.matrix[r][c] = self._dead
        end
    end
end

function Gol:alive(c, r)
    if self.matrix[r][c] == self._alive then
        return true
    end
    
    return false
end

function Gol:dead(c, r)
    if self.matrix[r][c] == self._dead then
        return true
    end
    
    return false
end

function Gol:calculate()
    local n    = 0
    local tab  = self.matrix
    
    -- Neighbour positions from the current index
    local nbrs = {
        {-1,-1},
        {-1,0},
        {-1,1},
        {0,-1},
        {0,1},
        {1,-1},
        {1,0},
        {1,1}
    }
    
    for r = 2, self.rows - 1 do
        for c = 2, self.columns - 1 do
            n = 0
            
            -- How many neighbours does this cell have?
            for _,a in ipairs(nbrs) do
                if self:alive(c + a[2], r + a[1]) then
                    n = n + 1
                end
            end

            -- Kill or live
            if self:alive(c, r) and n < 2 then
                tab[r][c] = self._dead
            elseif self:alive(c, r) and (n == 2 or n == 3) then
                tab[r][c] = self._alive
            elseif self:alive(c, r) and n >= 3 then
                tab[r][c] = self._dead
            elseif self:dead(c, r) and n == 3 then
                tab[r][c] = self._alive
            end
           
        end
    end
end

function Gol:draw()
    for r = 1, self.rows do
        for c = 1, self.columns do
            self.drawMethod({
                x = c,
                y = r,
                s = self.matrix[r][c]
            })
        end
    end
end

function Gol:touched(touch)
    local x = math.floor(touch.x / (WIDTH / self.columns))
    local y = math.floor(touch.y / (HEIGHT / self.rows))
    
    self.matrix[y][x] = self._alive
end

main.lua

-- golly

-- Use this function to perform your initial setup
function setup()
    parameter.color("DeadCellColour", color(123,123,223,255))
    parameter.color("AliveCellColour", color(10,10,10,255))
    parameter.color("Background", color(255,255,255,255))
    parameter.boolean("Play")
    
    gol = Gol(30, 30)

    gol.drawMethod = function (cell)
        wid = WIDTH / 30
        hei = HEIGHT / 30
    
        if cell.s == gol._alive then
            fill(AliveCellColour)
        else
            fill(DeadCellColour)
        end
        rect(wid * (cell.x - 1), hei * cell.y, wid, hei)
    end
end

-- This function gets called once every frame
function draw()
    -- This sets a dark background color 
    background(Background)

    -- If we've paused, stop calculating
    if Play then
        gol:calculate()
    end
    
    -- Always draw
    gol:draw()
end

function touched(t)
    gol:touched(t)
end