Snake

snake.lua

TILE_SIZE = 10

TILES_WIDE = love.graphics.getWidth()/TILE_SIZE
TILES_HIGH = love.graphics.getHeight()/TILE_SIZE

LENGTH_INCREMENT = 5
TRUD_INCREMENT = 5

ACCUMULATOR = 0

snake = {
	speed = 20,
	position = {x = love.graphics.getWidth()/2, y = love.graphics.getHeight()/2},
	velocity = {x = 1, y = 0},
	length = 5,
	trudCount = 0,
	body = {},
}

truds = {{x = 5, y = 5}}

function coord_eql(a, b)
	return (a.x == b.x and a.y == b.y)
end

function love.load()
end

function love.keypressed(key)
	if key == "up" then
		snake.velocity = {x =  0, y = -1}
	elseif key == "down" then
		snake.velocity = {x =  0, y =  1}
	elseif key == "left" then
		snake.velocity = {x = -1, y =  0}
	elseif key == "right" then
		snake.velocity = {x =  1, y =  0}
	end
end

function step(fixed_dt)
	snake.position.x = snake.position.x + snake.velocity.x*TILE_SIZE
	snake.position.y = snake.position.y + snake.velocity.y*TILE_SIZE
	
	local pos = {
		x = math.floor(snake.position.x/TILE_SIZE),
		y = math.floor(snake.position.y/TILE_SIZE)
	}
	
	local len = #snake.body
	if len == 0 or not coord_eql(pos, snake.body[len]) then
		table.insert(snake.body, pos)
	end
	
	for i, body in pairs(snake.body) do
		if (not i == len) and coord_eql(pos, body) then
			print("die")
		end
	end
	
	if #snake.body > snake.length then
		if snake.trudCount > 0 then
			table.insert(truds, snake.body[1])
			snake.trudCount = snake.trudCount - 1
		end
		
		table.remove(snake.body, 1)
	end
	
	local trudsCopy = {}
	for i, trud in pairs(truds) do
		if coord_eql(pos, trud) then
			snake.length = snake.length + LENGTH_INCREMENT
			snake.trudCount = snake.trudCount + TRUD_INCREMENT
		else
			table.insert(trudsCopy, trud)
		end
	end
	truds = trudsCopy
end

function love.update(dt)
	ACCUMULATOR = ACCUMULATOR + dt
	local fixed_dt = 1.0/snake.speed
	
	while ACCUMULATOR > fixed_dt do
		ACCUMULATOR = ACCUMULATOR - fixed_dt
		step(fixed_dt)
	end
end

function love.draw()
	local len = #snake.body
	for i, p in pairs(snake.body) do
		if i == len then
			love.graphics.setColor(255, 0, 0)
		else 
			love.graphics.setColor(0, 255, 0)
		end
		love.graphics.rectangle("fill", p.x*TILE_SIZE, p.y*TILE_SIZE, TILE_SIZE, TILE_SIZE)
	end
	
	for i, p in pairs(truds) do
		love.graphics.setColor(143, 80, 18)
		love.graphics.rectangle("fill", p.x*TILE_SIZE, p.y*TILE_SIZE, TILE_SIZE, TILE_SIZE)
	end
end