From 4f4c6e4c5e729c90bee24c813efbc1e76bdca470 Mon Sep 17 00:00:00 2001
From: Brychan Dempsey <brychand@hotmail.com>
Date: Thu, 3 Jun 2021 13:25:17 +1200
Subject: [PATCH] Added ECS docs

---
 docs/component/component.md | 49 +++++++++++++++++++++++++++++++++++++
 docs/entity/entity.md       | 37 ++++++++++++++++++++++++++++
 docs/system/system.md       | 24 ++++++++++++++++++
 3 files changed, 110 insertions(+)
 create mode 100644 docs/component/component.md
 create mode 100644 docs/entity/entity.md
 create mode 100644 docs/system/system.md

diff --git a/docs/component/component.md b/docs/component/component.md
new file mode 100644
index 0000000..d74d33d
--- /dev/null
+++ b/docs/component/component.md
@@ -0,0 +1,49 @@
+# Component
+### Contents
+[About](#About)
+
+## About
+Components are raw data that gets associated with an entity.
+
+For an Object-Oriented language like Java, they are objects.
+
+Each component is an array of objects, containing the data that should be associated with the entity.
+
+E.g.: A position component is defined such as:
+``` java
+class position{
+    double x = 0.0;
+    double y = 0.0;
+}
+```
+
+<br>
+
+As the component is simply an object, the associated data can be anything, including scripts:
+``` java
+class script{
+    String statement = "";
+    Function<void> foo = () -> {
+        statement += "boo";
+    };
+}
+```
+
+<br>
+<br>
+
+Two different usages of this data can then be applied:
+1. System-less data usage - which stores data but does not have a system that interacts with it every frame
+
+and 
+
+2. System-based interaction - which utilises the current data (of one or more components) to check if certain conditions have been met. 
+
+I.e.:
+
+The `position` component might not have a `position_system`, but may be utilised by the `collision_system`, which may use `position.x` and `position.y` to determine the location of the entity.
+
+See [System](./system/system.md) for more information.
+
+
+
diff --git a/docs/entity/entity.md b/docs/entity/entity.md
new file mode 100644
index 0000000..bd4afda
--- /dev/null
+++ b/docs/entity/entity.md
@@ -0,0 +1,37 @@
+# Entity
+### Contents
+[About](#About)
+
+[Usage](#Usage)
+
+[Notes](#Notes)
+
+## About
+An 'entity' is a unique ID.
+
+For most implementations, it makes sense to use a simple integer value - usually in a packed array (*reuses the most minimal value it can*)
+
+E.g.: The ID 101 would be the next selected value for a new entity.
+
+>100 | 101 | 102| 103| 104| ...|
+>:----:|:-----:|:----:|:----:|:----:|:----|
+><span style="color:gray">used|unused|<span style="color:gray">used|<span style="color:gray">used| unused| <span style="color:gray">....
+<br>
+
+**This ID represents a specific instance of a game object**
+
+e.g. character, vehicle, effect etc.
+
+___An entity contains no further data.___
+
+In order to be useful, its identifier must be registered to one or more [components](./component/component.md).
+
+## Usage
+*some specific usage info here*
+``` java
+void todo();
+```
+
+## Notes
+* The only requirement for a Entity is that it has a unique ID. An [entity manager](./manager/entity_manager.md) could implement a more complex ID system such as using a packed array for only a small region of IDs, or using named IDs by use of a dictionary or ordered hash-map
+* 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.
diff --git a/docs/system/system.md b/docs/system/system.md
new file mode 100644
index 0000000..7ef9fe1
--- /dev/null
+++ b/docs/system/system.md
@@ -0,0 +1,24 @@
+# System
+### Contents
+[About](#About)
+
+## About
+The system runs operations that must be performed on its assoiciated components.
+
+Typically, this is expected to be run every frame, though this is not a strict requirement.
+
+Examples of the `system` include the `health_system`; which reads the value of the entitie's `health` component and ensures h > 0.
+``` java
+void health_system(){
+    for (i = 0; i < registeredComponents.size(); i++){
+        if (registeredComponents[i].health <= 0){
+            registeredComponents[i].dead = true;
+            if (registeredComponents[i].isPlayer){
+                GameOver();
+            }
+        }
+    }
+}
+```
+
+