function gameoflife;

%%% Game of life 
%%% 

clear;
clc;


%%% key parameters:

s=50;            % size of the grid (square s x s) - default: 50
n=300;           % number of initial living cells - default: 300
niter=40;        % number of iterations - default: 40


%%% additional parameters:

ms=5;           % margin size (to account to what happens just out of the border) - default: 5
speed=0.4;      % speed (number of seconds/frame) - default: 0.4


%%% total size of the grid and total number of living cells:

ts=s+2*ms;         % size of the full grid
tn=n*(ts^2/s^2);   % number of living cells in the full grid


%%% generate random pattern:

k=ceil(ts^2.*rand(tn,1));   % random


%%% pre-defined initial pattern:

%s=10; ms=1; ts=s+2*ms; niter=8; k=[53,54,65];                % stable block
%s=10; ms=1; ts=s+2*ms; niter=8; k=[53,54,55];                % blinker (periodic pattern)
%s=10; ms=1; ts=s+2*ms; niter=8; k=[53,54,55,64,65,66];       % toad (periodic pattern)
%s=20; ms=5; ts=s+2*ms; niter=70; k=[188,219,247,248,249];    % glider (spaceship)
%s=20; ms=5; ts=s+2*ms; niter=30; k=[193,195,226,256,283,286,314,315,316];  % glider (spaceship)
%s=40; ms=5; ts=s+2*ms; niter=120; speed=0.05; k=[870,871,874,920,923,970,973,974,1022,1070,1072,1073,1074];  % growing growing

%%% generate initial matrix

M=zeros(ts);
M(k)=1;


%%% run the game

figure(1);
clf;

for i=0:niter
   fprintf('.');
   pause(speed);
   if i>0
   M=update(M);
   end
   Mout=ones(s)-M([ms:end-ms-1],[ms:end-ms-1]);
   h=imagesc(Mout);
   colormap(gray);
   set(gca,'XTickLabel',{''})    % to remove x tick labels
   set(gca,'YTickLabel',{''})    % to remove y tick labels
   set(gca,'XTick',[0.5:1:s])    % to remove x ticks
   set(gca,'YTick',[0.5:1:s])    % to remove y ticks
   grid on
end

fprintf('\n\n');


end


% ==================================================
% Update matrix
% ==================================================

function P=update(M);

s=length(M);
P=zeros(s);

for i=2:s-1
  for j=2:s-1
      nn=M(i-1,j-1)+M(i,j-1)+M(i+1,j-1)+M(i-1,j)+M(i+1,j)+M(i-1,j+1)+M(i,j+1)+M(i+1,j+1);   % number of neighbourgs
      if(M(i,j)==0 && nn == 3)
          P(i,j)=1;
      elseif(M(i,j)==1 && nn >= 2 && nn <= 3)
          P(i,j)=1;
      end
  end
end


end