Game of life in Ruby

game_of_life.rb

=begin
Whenever we visit the cell in the pattern, we call this method 
to get the next state of the cell when the Tick happens.
Here, we add the values of all the eight cells around the visited cell
and apply the game_of_life rules as specified in the comments below.
=end
def next_gen(seed, row, col)
	next_state = 0
	(-1..1).each do |xdir|
		(-1..1).each do |ydir|
			if(xdir == 0 and ydir == 0)
				#do nothing
			else 
				if((col+xdir).between?(0,5) and (row+ydir).between?(0,3))
					next_state += seed[row+ydir][col+xdir]
				end
			end
		end
	end

	#apply rules now	
	if(seed[row][col] == 0)
		if(next_state == 3) 
			#dead cell resurrects if it has exactly 3 live neighbours
			next_state = 1
		else
			next_state = 0
		end
	else
		if(next_state == 2 or next_state == 3) 
			#live cells remains unchanged if they have 2/3 live neighbours
			next_state = 1
		else
			# or they die
			next_state = 0
		end
	end
	return next_state;
end

def display(seed)
	seed.each do |row|
		row.each do |col|
			print col
		end
		puts ""
	end
end

def onTick(seed)
	next_generation = []
	seed.each_with_index do |row, row_index|
		nextrow = []
		row.each_with_index do |cell, cell_index|	
			nextrow[cell_index]= next_gen(seed, row_index, cell_index)
		end
		next_generation[row_index]= nextrow
	end
	return next_generation
end

#Considers an extra layer of dead cells i.e 0s around the actual pattern e.g.
=begin
if the pattern is 
-xxx
xxx-

then the input must be
------
--xxx-
-xxx--
------
=end
seed = [ [0,0,0,0,0,0],[0,0,1,1,1,0],[0,1,1,1,0,0],[0,0,0,0,0,0] ]

puts "Input Pattern : "
display seed

puts "Here is the Output : "
display(onTick(seed))