Let us imagine a crazy scenario. You live in a forest, without convenient access to furniture shops, which means when you need a chair, you have to craft it by yourself. If you have to craft a new chair every single time you need to use it, it is very inconvenient. The Object Pool pattern's intention is to create a bunch of chairs when you just move in to the forest, so that when you need to use it you just need to take it out from your warehouse.
- Create an empty object and attach Pool Manager script.
- For each prefab that you want to put into pool, create an empty object as a child of the object above and attach Pool script to it. Assign the prefab value and put an integer value so that the pool create a few instances for you.
For example, the ObjectPools object holds the Pool Manager scripts, while its three children have Pool script.
Very simple, normally when you need a new instance of a prefab, you do this:
... you just need to replace the Instantiate line to this:
I provided a few overloaded versions so that you can use the pattern naturally and conveniently. The same applied when deleting objects, you just need to replace Destroy(gameObject) to gameObject.Despawn().
You can also implement two special events: OnSpawn, which is called when the object is spawned if you call prefab.Spawn() and its variations, and OnPreDisable, which is called when the object is destroyed with object.Despawn():
I wrote a blog post about this matters ealier, you can check it out here: http://tongtunggiang.com/blog/2017/09/19/simple-object-pool-better-performance-games/
In case you have any confusion, feel free to contact me via social links that I provided in my website.