Conway's game of life with ASCII output

gameoflife.rb

#!/usr/bin/env ruby

STDOUT.sync = true

# Create the grid

class Grid

  def initialize(height, width)
		@width = width
		@height = height
		@grid = Array.new(@height) { Array.new(@width)}
		@height.times do |row|
			@width.times do |col|
				@grid[row][col] = " "
			end
		end
	end

	def show()
		puts "\e[H\e[2J"
		@height.times do |row|
			print "\r"
			@width.times do |col|
				print @grid[row][col]
			end
			print "\n"
		end
	end

	def toggle(x, y)
		if @grid[x-1][y-1] == " "
			@grid[x-1][y-1] = "X"
		elsif @grid[x-1][y-1] == "X"
			@grid[x-1][y-1] = " "
		end
	end

	def reset
		@height.times do |row|
			@width.times do |col|
				@grid[row][col] = " "
			end
		end
	end

	def toggleRandCoords
		xrand = rand(@height) + 1
		yrand = rand(@width) + 1
		toggle(xrand, yrand)
	end

	# spawn the universe
	def spawn(count)
		count.times do
			toggleRandCoords
		end
	end

	# calculate the next generation
	def nextGen
		nextGrid = Array.new(@height) { Array.new(@width)}
		@height.times do |row|
			@width.times do |col|
				nextGrid[row][col] = " "
			end
		end
		@height.times do |row|
			@width.times do |col|
				upperRow = row-1
				lowerRow = row+1
				leftColumn = col-1
				rightColumn = col+1
				# Check the number of living neighbours
				livingNeighbours = 0
				# check the upperleft neighbour
				if ((upperRow >= 0) && (leftColumn >= 0) && (@grid[upperRow][leftColumn].eql? "X"))
					livingNeighbours = livingNeighbours + 1
				end
				# check the above neighbour
				if ((upperRow >= 0) && (@grid[upperRow][col].eql? "X"))
					livingNeighbours = livingNeighbours + 1
				end
				# check the upperright neighbour
				if ((upperRow >= 0) && (rightColumn < @width) && (@grid[upperRow][rightColumn].eql? "X"))
					livingNeighbours = livingNeighbours + 1
				end
				# check the left neighbour
				if ((leftColumn >= 0) && (@grid[row][leftColumn].eql? "X"))
					livingNeighbours = livingNeighbours + 1
				end
				# check the right neighbour
				if ((rightColumn < @width) && (@grid[row][rightColumn].eql? "X"))
					livingNeighbours = livingNeighbours + 1
				end
				# check the lowerleft neighbour
				if ((lowerRow < @height) && (leftColumn >= 0) && (@grid[lowerRow][leftColumn].eql? "X"))
					livingNeighbours = livingNeighbours + 1
				end
				# check the under neighbour
				if ((lowerRow < @height) && (@grid[lowerRow][col].eql? "X"))
					livingNeighbours = livingNeighbours + 1
				end
				# check the lowerright neighbour
				if ((lowerRow < @height) && (rightColumn < @width) && (@grid[lowerRow][rightColumn].eql? "X"))
					livingNeighbours = livingNeighbours + 1
				end

				# Set the new state of the cell according to its current state and the neighbours
				if @grid[row][col] == " "
					if livingNeighbours == 3
						nextGrid[row][col] = "X"
					end
				elsif @grid[row][col] == "X"
					if (livingNeighbours == 1)
						nextGrid[row][col] = " "
					elsif ((livingNeighbours == 2) || (livingNeighbours == 3))
						nextGrid[row][col] = "X"
					else
						nextGrid[row][col] = " "
					end
				end
			end
		end
		@grid = nextGrid
	end
end

ROWS = 30
COLS = 200
SPAWN = 4000
SLEEP = 0.1
game = Grid.new(ROWS, COLS)
game.spawn (SPAWN)
game.show
sleep(SLEEP)
while true
	game.nextGen
	game.show
	sleep(SLEEP)
end