- Initial commit

.gitignore

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+.dub
+docs.json
+__dummy.html
+*.o
+*.obj
+decs.exe
+dub.selections.json
+source/app.d

LICENSE.md

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+Boost Software License - Version 1.0 - August 17th, 2003
+
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

README.md

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+/** Works in progress **/
+
+decs
+===========
+
+decs is my attempt to build a @nogc D language Entity Component System. 
+I'm not really an game dev, im trying to learn how an ECS works so some portions of this code can be inefficients or bug prone.
+
+It's inspired by the following projects : 
+
+https://github.com/miguelmartin75/anax  => C++ ECS
+https://github.com/jzhu98/star-entity   => D ECS
+https://github.com/claudemr/entitysysd  => D ECS
+
+## How to build
+
+You have to use [dub](https://code.dlang.org/download) to build the project.
+
+Add this project as a dependency to your **dub.json**:
+
+```json
+"dependencies": {
+    "decs": "~>1.0.0"
+}
+```
+
+## How to use
+
+### Entity Manager
+
+```cs
+
+import decs;
+
+void main()
+{
+    auto em = new EntityManager();
+
+    while(game)
+    {
+        em.update(dt);
+    }
+
+    // !important!
+    em.dispose();
+}
+
+```
+
+### Entities
+
+You can create an entity, kill it, invalidate it or activate it (still need some work here). 
+
+```cs
+auto entity = em.createEntity();
+
+// Notifies all systems that a new entity is alive (check system section to understand this part)
+entity.activate();
+
+// Entity is still alive but will be invalid in current scope
+entity.invalidate();
+
+// Poor entity :<
+entity.kill();
+```
+
+### Components
+
+An component must be represented as a struct.
+
+```cs
+struct PositionComponent
+{
+    float x, y, z;
+}
+```
+
+You can add a component to an entity :
+
+```cs
+// add
+entity.add!PositionComponent(1, 2, 3);
+
+// update (its handled as a pointer)
+entity.get!PositionComponent().y = 50;
+
+// check
+if(entity.has!PositionComponent())
+{
+    // ...
+}
+```
+### Systems
+
+An system must be a class that inherits **decs.System**.
+
+```cs
+class MovementSystem : System
+{
+    public void update(in float delta)
+    {
+
+    }
+}
+```
+There is 2 ways to query entities from your system : 
+
+* 1 => Using entity manager **entities!(components...)** function
+* 2 => Using the components filter mixin **mixin ComponentsFilter!(components...);**
+
+
+If you provide an components filter, when an entity is activated, it will be automatically added to the systems whose filters match her components.
+
+```cs
+class MovementSystem : System
+{
+    // option 2
+    mixin ComponentsFilter!(PositionComponent);
+
+    public void update(in float deltaTime)
+    {
+        // option 1
+        auto entities = this.m_entityManager.entities!(PositionComponent);
+
+        // option 2 (should be more efficient)
+        foreach(entity; this.m_entities)
+        {
+
+        }
+    }
+}
+```
+System's update method will be called automatically by the entity manager in the main loop. If you want to handle the update manually, you can set the **System.UpdatePolicy** to manual :
+
+```cs
+class MovementSystem : System
+{
+    public this()
+    {
+        super(System.UpdatePolicy.Manual);
+    }
+}
+
+// ...
+
+while(game)
+{
+    em.update(dt);
+
+    // you have to call it manually (before or after the em.update call)
+    myMovementSystem.update(dt);
+}
+```
+
+### Events
+
+wip
+
+## TODOs
+
+* Add **@component** and **@event** UDAs
+* Add the possibility to defines systems execution order when using **em.update(dt)**
+* Add anexample project
+* Improve this readme

dub.json

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+{
+	"name": "decs",
+	"authors": [
+		"aldo"
+	],
+	"dependencies": {
+		"dnogc": "~master"
+	},
+	"description": "@nogc D Entity Component System",
+	"license": "Boost Software License"
+}

source/decs/Component.d

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+module decs.Component;
+
+struct GlobalComponentCounter
+{
+    static uint counter = 0;
+}
+
+/**
+ * Helper used to get an unique id per component
+ */
+struct ComponentCounter(Component)
+{
+    private GlobalComponentCounter globalComponentCounter;
+
+    public static uint getId() nothrow @safe @nogc
+    {
+        static uint counter = -1;
+
+        if(counter == -1)
+        {
+            counter = globalComponentCounter.counter;
+            globalComponentCounter.counter++;
+        }
+
+        return counter;
+    }
+}

source/decs/ComponentPool.d

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+module decs.ComponentPool;
+
+import dnogc.DynamicArray;
+
+interface IComponentPool
+{
+    public void dispose();
+    public void expand() nothrow @safe @nogc;
+    public size_t length() const pure nothrow @safe @nogc;
+}
+
+class ComponentPool(T) : IComponentPool
+{
+    private DynamicArray!T m_components;
+
+    public this(in size_t poolSize) nothrow @safe @nogc
+    {
+        this.m_components = DynamicArray!T(poolSize);
+        this.m_components.length = poolSize;
+    }
+
+    public void dispose()
+    {
+        this.m_components.dispose();
+    }
+
+    public void insert()(auto ref T component) nothrow @safe @nogc
+    {
+        this.m_components.insert(component);
+    }
+
+    /**
+     * Returns the component at the specified index
+     * Params:
+     *      index : 
+     */
+    public T* get(in uint index) pure nothrow @trusted @nogc
+    {
+        assert(index < this.m_components.length);
+
+        immutable ptr = index * T.sizeof;
+
+        auto data = this.m_components.ptr;
+
+        return cast(T*)data[ptr..(ptr + T.sizeof)];
+    }
+
+    /**
+     * Sets the value of the component at the specified index
+     * Params:
+     *      index : 
+     *      component :
+     */
+    public void set(in uint index, ref T component) pure nothrow @safe @nogc
+    {
+        assert(index < this.m_components.length);
+
+        this.m_components[index] = component;
+    }
+
+    /**
+     * Expands the pool with an empty value
+     */
+    public void expand() nothrow @safe @nogc
+    {
+        this.m_components.insert(T());
+    }
+
+    @property
+    public size_t length() const pure nothrow @safe @nogc
+    {
+        return this.m_components.length;
+    }
+}