Simple Item Pool Class

vitalitymobile · April 2014

Here is simple item pool code for http://giderosmobile.com/forum/discussion/4767/fully-automatic-spawning-class

ar2rsawseen · April 2014

Great,
hmm, how about instead of simply removing items, you cache them and reuse them? That way it will be more efficient because there won't be clogging a memory with removed items and no overhead of allocating memory to new items

vitalitymobile · April 2014

Yes yes thank you, @ar2rsawseen!

HubertRonald · April 2014

Thanks for sharing @vitalitymobile

Great,
hmm, how about instead of simply removing items, you cache them and reuse them? That way it will be more efficient because there won't be clogging a memory with removed items and no overhead of allocating memory to new items

@ar2rsawseen, would be something like the example that comes with Gideros. (Bird Animation) only there are four birds!

ar2rsawseen · April 2014

Yes, well the pool with unlimited amount of objects could be like this:

 
Pool = Core.class(Sprite)
 
function Pool:init()
    self.pool = {}
end
 
function Pool:createObject()
    local b
    --if there is anything in pool take it
    if #self.pool > 0 then
        b = table.remove(self.pool)
    else
        b = Bitmap.new(Texture.new("image.png", true))
    end
    stage:addChild(b)
    return b
end
 
function Pool:destroyObject(b)
    b:removeFromParent()
    table.insert(#self.pool, b)
end

bthomsen · August 2020

Here is the implementation I wrote for a game I'm working on. Hopefully someone will find it useful.

--[[
 
	Storage to recycle bitmaps for use later.
 
	Originally written by Brant D. Thomsen
	Contributed to the public domain
 
]]
 
local bitmapList = {}
 
-- Returns the bitmapList index for the texture, or 0 if not found.
-- Does a binary search for efficiency.
local function findTextureIndex(textureString)
	local low = 1
	local high = #bitmapList
	local mid
	while low < high do
		mid = math.floor((low + high) / 2)
		if textureString < bitmapList[mid][1] then
			high = mid - 1
		elseif textureString > bitmapList[mid][1] then
			low = mid + 1
		else
			return mid
		end
	end
	if low == high and textureString == bitmapList[low][1] then
		return low
	end
	return 0
end
 
-- Get a bitmap from the pool, if there is one there.
-- Otherwise, a new bitmap is generated from the supplied texture.
function getBitmapFromPool(texture)
	-- Return a bitmap if we already have one.
	local index = findTextureIndex(tostring(texture))
	if index > 0 and #bitmapList[index][2] > 0 then
		return table.remove(bitmapList[index][2], #bitmapList[index][2])
	end
 
	-- Create a new bitmap and return it.
	return Bitmap.new(texture)
end
 
-- Add a bitmap with the supplied texture back to the pool.
-- Removes the bitmap from the object holding it.
function putBitmapBackIntoPool(texture, bitmap)
	assert(texture)
	assert(bitmap)
	bitmap:removeFromParent()
	bitmap:setAlpha(1.0)
 
	-- Add to the pool, if there is already a place for it.
	local textureString = tostring(texture)
	local index = findTextureIndex(textureString)
	if index > 0 then
		table.insert(bitmapList[index][2], bitmap)
		return
	end
 
	-- Create a new texture list and add it to the pool.
	-- Insert it in the sorted position to allow for binary searches later.
	index = 1
	while index <= #bitmapList and textureString > bitmapList[index][1] do
		index = index + 1
	end
	table.insert(bitmapList, index, {textureString, {bitmap}})
	assert(index == 1 or bitmapList[index - 1][1] < textureString)
	assert(index == #bitmapList or bitmapList[index + 1][1] > textureString)
end

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