40 lines
1.6 KiB
Markdown
40 lines
1.6 KiB
Markdown
*| [JavaECS](../../README.md) | [docs](../overview.md) | [entity](./dir.md) | Entity[]().md*
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# Entity
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### Contents
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[About](#about)
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[Usage](#usage)
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[Notes](#notes)
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## About
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An 'entity' is a unique ID.
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For most implementations, it makes sense to use a simple integer value to represent an entity. As each entity must have a unique
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ID/number, we can use a First-In-First-Out (FIFO) data structure, such as a Queue, to efficiently retrieve the next unassigned ID.
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<br>
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**This ID represents a specific instance of a game object**
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e.g. character, vehicle, effect etc.
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___An entity contains no further data.___
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In order to be useful, its identifier must be registered to one or more [components](../component/Component.md).
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Entities are also initialised with a Java [BitSet](https://docs.oracle.com/javase/7/docs/api/java/util/BitSet.html). Each bit represents the index of a component, to determine which component an entity is registered to.
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## Usage
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*some specific usage info here*
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``` java
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void todo();
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```
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## Notes
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* The only requirement for a Entity is that it has a unique ID. A more advanced [entity manager](../manager/EntityManager.md) could implement an ID system with ID regions, or using named IDs.
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Another approach could be to use the first byte as a grouping, in a similar way to how Bethesda Softworks' Skyrim utilises the first byte as a mod index
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* The maximum number of entities is limited by the size of the container used to store it. E.g., for a 32-bit unsigned integer, there are ~4.3 billion ID's available. But keep in mind that such a large amount of IDs will take significant time for each system to consider.
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