Sometimes you want to be able to refer to specific items in your collection by a key. The key could still be an index, but might be a scenario where your collection doesn’t include all of the indices – perhaps it didn’t start at zero or skips items. Alternatively you might want to map an item to something else, like a string of text. These are the kinds of cases where a Dictionary makes more sense than a List. Our final pooler and demo will be based on this use case.
In many scenarios, the collection of “Poolable” items itself is relevant to their use. If you want to think of the collection as having an “order” then the collection should probably be implemented as a “List”. Follow along and I will show another pooler based on a list along with a demo scene showing how to use it.
In some scenarios, the collection of “Poolable” items itself isn’t relevant to how you are using them. If you have no need of iterating over and applying logic to the entire group then you might be satisfied with using a simple “Set” to contain them. For example, an explosion might be pooled after its animation has completed and a bullet might be pooled after it hits an object or leaves a game zone. Scenario’s with event-based pooling might be a perfect fit for our first Pooler subclass.
After having used my pooling library for awhile I found myself putting similar implementation code all over my scripts. With a bit of thought I realized that I could eliminate a lot of the code by creating another component. Actually I will be creating several, but they all serve the same purpose of helping reduce the amount of code necessary to work with pooled items.
Object pooling is a relatively common practice in games. By reusing your GameObjects instead of destroying and recreating them you can save precious CPU cycles. It is easy to find a lot of free scripts and tutorials on the subject – even Unity has provided one in a Live Training session. Their presentation, while a great introduction, was not what I would consider production ready. In this post I’ll share my thoughts on their implementation as well as how I would improve upon it.