Physics Engine (#4)

* Add matter-js as a dependency

* Add body component

* Fix renderable node doc

* Add the physics node type

* Correct typo in physics enabled node types

* Update docs on render system

* Add physics system

* Update changelog

* Add physics engine to main app

* Tweak the gravity of the world

* Add body to sumo factory

* Add angle component

* Add angle to entity

* Add angle to the nodes

* Pass angle between systems

* Set default angle to 0

* Split systems and nodes

* Fix indentaion in physics world control

* Add third sumo entity

* Adjust values for constriants and physics

* Correct docs in new nodes

* Update built-in docs

1 files changed, 584 insertions, 0 deletions

diff --git a/doc/README.md b/doc/README.md
index 2d79f30..2d367a5 100644
--- a/doc/README.md
+++ b/doc/README.md
@@ -1,3 +1,268 @@
+## Classes
+
+<dl>
+<dt><a href="#AngleComponent">AngleComponent</a> ⇐ <code>external:Serpentity.Component</code></dt>
+<dd></dd>
+<dt><a href="#BodyComponent">BodyComponent</a> ⇐ <code>external:Serpentity.Component</code></dt>
+<dd></dd>
+<dt><a href="#CoupledEntitiesComponent">CoupledEntitiesComponent</a> ⇐ <code>external:Serpentity.Component</code></dt>
+<dd></dd>
+<dt><a href="#PixiContainerComponent">PixiContainerComponent</a> ⇐ <code>external:Serpentity.Component</code></dt>
+<dd></dd>
+<dt><a href="#PhysicalWithAttributesNode">PhysicalWithAttributesNode</a> ⇐ <code>external:Serpentity.Node</code></dt>
+<dd></dd>
+<dt><a href="#PhysicalNode">PhysicalNode</a> ⇐ <code>external:Serpentity.Node</code></dt>
+<dd></dd>
+<dt><a href="#RenderableCoupleNode">RenderableCoupleNode</a> ⇐ <code>external:Serpentity.Node</code></dt>
+<dd></dd>
+<dt><a href="#RenderableWithAttributesNode">RenderableWithAttributesNode</a> ⇐ <code>external:Serpentity.Node</code></dt>
+<dd></dd>
+<dt><a href="#RenderableNode">RenderableNode</a> ⇐ <code>external:Serpentity.Node</code></dt>
+<dd></dd>
+<dt><a href="#Sumo">Sumo</a></dt>
+<dd></dd>
+<dt><a href="#AttributesToRenderableSystem">AttributesToRenderableSystem</a> ⇐ <code>external:Serpentity.System</code></dt>
+<dd></dd>
+<dt><a href="#CreateCouplingLineSystem">CreateCouplingLineSystem</a> ⇐ <code>external:Serpentity.System</code></dt>
+<dd></dd>
+<dt><a href="#PhysicsToAttributesSystem">PhysicsToAttributesSystem</a> ⇐ <code>external:Serpentity.System</code></dt>
+<dd></dd>
+<dt><a href="#PhysicsWorldControlSystem">PhysicsWorldControlSystem</a> ⇐ <code>external:Serpentity.System</code></dt>
+<dd></dd>
+<dt><a href="#RenderSystem">RenderSystem</a> ⇐ <code>external:Serpentity.System</code></dt>
+<dd></dd>
+</dl>
+
+## Members
+
+<dl>
+<dt><a href="#PixiFactory">PixiFactory</a> : <code>object</code></dt>
+<dd><p>Factory object that contains many methods to create prefab pixi
+objects</p>
+</dd>
+<dt><a href="#SumoFactory">SumoFactory</a> : <code>object</code></dt>
+<dd><p>Factory object that contains many methods to create prefab entities.</p>
+</dd>
+</dl>
+
+<a name="AngleComponent"></a>
+
+## AngleComponent ⇐ <code>external:Serpentity.Component</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.Component</code>  
+<a name="new_AngleComponent_new"></a>
+
+### new AngleComponent(config)
+Component that stores an angle
+
+
+| Param | Type | Description |
+| --- | --- | --- |
+| config | <code>object</code> | a configuration object to extend. |
+
+<a name="BodyComponent"></a>
+
+## BodyComponent ⇐ <code>external:Serpentity.Component</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.Component</code>  
+<a name="new_BodyComponent_new"></a>
+
+### new BodyComponent(config)
+Component that stores a body for physics calculation
+
+
+| Param | Type | Description |
+| --- | --- | --- |
+| config | <code>object</code> | a configuration object to extend. |
+
+<a name="CoupledEntitiesComponent"></a>
+
+## CoupledEntitiesComponent ⇐ <code>external:Serpentity.Component</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.Component</code>  
+<a name="new_CoupledEntitiesComponent_new"></a>
+
+### new CoupledEntitiesComponent(config)
+Component that stores a number of entities coupled to this one.
+
+
+| Param | Type | Description |
+| --- | --- | --- |
+| config | <code>object</code> | a configuration object to extend. |
+
+<a name="PixiContainerComponent"></a>
+
+## PixiContainerComponent ⇐ <code>external:Serpentity.Component</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.Component</code>  
+
+* [PixiContainerComponent](#PixiContainerComponent) ⇐ <code>external:Serpentity.Component</code>
+    * [new PixiContainerComponent(config)](#new_PixiContainerComponent_new)
+    * [.container](#PixiContainerComponent+container)
+
+<a name="new_PixiContainerComponent_new"></a>
+
+### new PixiContainerComponent(config)
+Component that stores a pixi container
+
+
+| Param | Type | Description |
+| --- | --- | --- |
+| config | <code>object</code> | a configuration object to extend. |
+
+<a name="PixiContainerComponent+container"></a>
+
+### pixiContainerComponent.container
+The properthy that holds the pixi container
+
+**Kind**: instance property of [<code>PixiContainerComponent</code>](#PixiContainerComponent)  
+**Properties**
+
+| Name | Type |
+| --- | --- |
+| container | <code>external:PixiJs.Container</code> | 
+
+<a name="PhysicalWithAttributesNode"></a>
+
+## PhysicalWithAttributesNode ⇐ <code>external:Serpentity.Node</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.Node</code>  
+
+* [PhysicalWithAttributesNode](#PhysicalWithAttributesNode) ⇐ <code>external:Serpentity.Node</code>
+    * [new PhysicalWithAttributesNode()](#new_PhysicalWithAttributesNode_new)
+    * [.types](#PhysicalWithAttributesNode.types)
+
+<a name="new_PhysicalWithAttributesNode_new"></a>
+
+### new PhysicalWithAttributesNode()
+Node identifying an entity that can interact with physics and has
+components updated from its values
+
+<a name="PhysicalWithAttributesNode.types"></a>
+
+### PhysicalWithAttributesNode.types
+Holds the types that are used to identify an entity with a physics
+object and external attributes
+
+**Kind**: static property of [<code>PhysicalWithAttributesNode</code>](#PhysicalWithAttributesNode)  
+**Properties**
+
+| Name | Type |
+| --- | --- |
+| types | <code>object</code> | 
+
+<a name="PhysicalNode"></a>
+
+## PhysicalNode ⇐ <code>external:Serpentity.Node</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.Node</code>  
+
+* [PhysicalNode](#PhysicalNode) ⇐ <code>external:Serpentity.Node</code>
+    * [new PhysicalNode()](#new_PhysicalNode_new)
+    * [.types](#PhysicalNode.types)
+
+<a name="new_PhysicalNode_new"></a>
+
+### new PhysicalNode()
+Node identifying an entity that can interact with physics
+
+<a name="PhysicalNode.types"></a>
+
+### PhysicalNode.types
+Holds the types that are used to identify an entity with a physical
+body
+
+**Kind**: static property of [<code>PhysicalNode</code>](#PhysicalNode)  
+**Properties**
+
+| Name | Type |
+| --- | --- |
+| types | <code>object</code> | 
+
+<a name="RenderableCoupleNode"></a>
+
+## RenderableCoupleNode ⇐ <code>external:Serpentity.Node</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.Node</code>  
+
+* [RenderableCoupleNode](#RenderableCoupleNode) ⇐ <code>external:Serpentity.Node</code>
+    * [new RenderableCoupleNode()](#new_RenderableCoupleNode_new)
+    * [.types](#RenderableCoupleNode.types)
+
+<a name="new_RenderableCoupleNode_new"></a>
+
+### new RenderableCoupleNode()
+Node identifying an entity that has coupled entities and can be
+rendered
+
+<a name="RenderableCoupleNode.types"></a>
+
+### RenderableCoupleNode.types
+Holds the types that are used to identify a renderable couple
+
+**Kind**: static property of [<code>RenderableCoupleNode</code>](#RenderableCoupleNode)  
+**Properties**
+
+| Name | Type |
+| --- | --- |
+| types | <code>object</code> | 
+
+<a name="RenderableWithAttributesNode"></a>
+
+## RenderableWithAttributesNode ⇐ <code>external:Serpentity.Node</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.Node</code>  
+
+* [RenderableWithAttributesNode](#RenderableWithAttributesNode) ⇐ <code>external:Serpentity.Node</code>
+    * [new RenderableWithAttributesNode()](#new_RenderableWithAttributesNode_new)
+    * [.types](#RenderableWithAttributesNode.types)
+
+<a name="new_RenderableWithAttributesNode_new"></a>
+
+### new RenderableWithAttributesNode()
+Node identifying a renderable entity, should have position and a
+symbol to render
+
+<a name="RenderableWithAttributesNode.types"></a>
+
+### RenderableWithAttributesNode.types
+Holds the types that are used to identify a renderable with external
+attributes
+
+**Kind**: static property of [<code>RenderableWithAttributesNode</code>](#RenderableWithAttributesNode)  
+**Properties**
+
+| Name | Type |
+| --- | --- |
+| types | <code>object</code> | 
+
+<a name="RenderableNode"></a>
+
+## RenderableNode ⇐ <code>external:Serpentity.Node</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.Node</code>  
+
+* [RenderableNode](#RenderableNode) ⇐ <code>external:Serpentity.Node</code>
+    * [new RenderableNode()](#new_RenderableNode_new)
+    * [.types](#RenderableNode.types)
+
+<a name="new_RenderableNode_new"></a>
+
+### new RenderableNode()
+Node identifying a renderable entity, should have a pixi renderable
+
+<a name="RenderableNode.types"></a>
+
+### RenderableNode.types
+Holds the types that are used to identify a renderable entity
+
+**Kind**: static property of [<code>RenderableNode</code>](#RenderableNode)  
+**Properties**
+
+| Name | Type |
+| --- | --- |
+| types | <code>object</code> | 
+
 <a name="Sumo"></a>
 
 ## Sumo
@@ -40,3 +305,322 @@ live until after you stop and start the loop)
 Pauses the loop
 
 **Kind**: instance method of [<code>Sumo</code>](#Sumo)  
+<a name="AttributesToRenderableSystem"></a>
+
+## AttributesToRenderableSystem ⇐ <code>external:Serpentity.System</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.System</code>  
+
+* [AttributesToRenderableSystem](#AttributesToRenderableSystem) ⇐ <code>external:Serpentity.System</code>
+    * [new AttributesToRenderableSystem(config)](#new_AttributesToRenderableSystem_new)
+    * [.added(engine)](#AttributesToRenderableSystem+added)
+    * [.removed()](#AttributesToRenderableSystem+removed)
+    * [.update(currentFrameDuration)](#AttributesToRenderableSystem+update)
+
+<a name="new_AttributesToRenderableSystem_new"></a>
+
+### new AttributesToRenderableSystem(config)
+Updates the renderables based on their attribuets
+
+
+| Param | Type | Description |
+| --- | --- | --- |
+| config | <code>object</code> | a configuration object to extend. |
+
+<a name="AttributesToRenderableSystem+added"></a>
+
+### attributesToRenderableSystem.added(engine)
+Initializes system when added. Requests renderable nodes and
+attaches to event listeners to add / remove them to pixi stage
+
+**Kind**: instance method of [<code>AttributesToRenderableSystem</code>](#AttributesToRenderableSystem)  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| engine | <code>external:Serpentity.Engine</code> | the serpentity engine to which we are getting added |
+
+<a name="AttributesToRenderableSystem+removed"></a>
+
+### attributesToRenderableSystem.removed()
+Clears system resources when removed.
+
+**Kind**: instance method of [<code>AttributesToRenderableSystem</code>](#AttributesToRenderableSystem)  
+<a name="AttributesToRenderableSystem+update"></a>
+
+### attributesToRenderableSystem.update(currentFrameDuration)
+Runs on every update of the loop. Updates the graphics so they're
+rendered correctly
+
+**Kind**: instance method of [<code>AttributesToRenderableSystem</code>](#AttributesToRenderableSystem)  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| currentFrameDuration | <code>Number</code> | the duration of the current frame |
+
+<a name="CreateCouplingLineSystem"></a>
+
+## CreateCouplingLineSystem ⇐ <code>external:Serpentity.System</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.System</code>  
+
+* [CreateCouplingLineSystem](#CreateCouplingLineSystem) ⇐ <code>external:Serpentity.System</code>
+    * [new CreateCouplingLineSystem(config)](#new_CreateCouplingLineSystem_new)
+    * [.added(engine)](#CreateCouplingLineSystem+added)
+    * [.removed()](#CreateCouplingLineSystem+removed)
+    * [.update(currentFrameDuration)](#CreateCouplingLineSystem+update)
+
+<a name="new_CreateCouplingLineSystem_new"></a>
+
+### new CreateCouplingLineSystem(config)
+Renders renderable objects using pixi
+
+
+| Param | Type | Description |
+| --- | --- | --- |
+| config | <code>object</code> | a configuration object to extend. |
+
+<a name="CreateCouplingLineSystem+added"></a>
+
+### createCouplingLineSystem.added(engine)
+Initializes system when added. Requests renderable nodes and
+
+**Kind**: instance method of [<code>CreateCouplingLineSystem</code>](#CreateCouplingLineSystem)  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| engine | <code>external:Serpentity.Engine</code> | the serpentity engine to which we are getting added |
+
+<a name="CreateCouplingLineSystem+removed"></a>
+
+### createCouplingLineSystem.removed()
+Clears system resources when removed.
+
+**Kind**: instance method of [<code>CreateCouplingLineSystem</code>](#CreateCouplingLineSystem)  
+<a name="CreateCouplingLineSystem+update"></a>
+
+### createCouplingLineSystem.update(currentFrameDuration)
+Runs on every update of the loop. Does nothing.
+
+**Kind**: instance method of [<code>CreateCouplingLineSystem</code>](#CreateCouplingLineSystem)  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| currentFrameDuration | <code>Number</code> | the duration of the current frame |
+
+<a name="PhysicsToAttributesSystem"></a>
+
+## PhysicsToAttributesSystem ⇐ <code>external:Serpentity.System</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.System</code>  
+
+* [PhysicsToAttributesSystem](#PhysicsToAttributesSystem) ⇐ <code>external:Serpentity.System</code>
+    * [new PhysicsToAttributesSystem(config)](#new_PhysicsToAttributesSystem_new)
+    * [.added(engine)](#PhysicsToAttributesSystem+added)
+    * [.removed()](#PhysicsToAttributesSystem+removed)
+    * [.update(currentFrameDuration)](#PhysicsToAttributesSystem+update)
+
+<a name="new_PhysicsToAttributesSystem_new"></a>
+
+### new PhysicsToAttributesSystem(config)
+Distribuets physics data to the related components
+
+
+| Param | Type | Description |
+| --- | --- | --- |
+| config | <code>object</code> | a configuration object to extend. |
+
+<a name="PhysicsToAttributesSystem+added"></a>
+
+### physicsToAttributesSystem.added(engine)
+Initializes system when added. Requests physics nodes
+
+**Kind**: instance method of [<code>PhysicsToAttributesSystem</code>](#PhysicsToAttributesSystem)  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| engine | <code>external:Serpentity.Engine</code> | the serpentity engine to which we are getting added |
+
+<a name="PhysicsToAttributesSystem+removed"></a>
+
+### physicsToAttributesSystem.removed()
+Clears system resources when removed.
+
+**Kind**: instance method of [<code>PhysicsToAttributesSystem</code>](#PhysicsToAttributesSystem)  
+<a name="PhysicsToAttributesSystem+update"></a>
+
+### physicsToAttributesSystem.update(currentFrameDuration)
+Runs on every update of the loop. Updates the other components
+based on physics
+
+**Kind**: instance method of [<code>PhysicsToAttributesSystem</code>](#PhysicsToAttributesSystem)  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| currentFrameDuration | <code>Number</code> | the duration of the current frame |
+
+<a name="PhysicsWorldControlSystem"></a>
+
+## PhysicsWorldControlSystem ⇐ <code>external:Serpentity.System</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.System</code>  
+
+* [PhysicsWorldControlSystem](#PhysicsWorldControlSystem) ⇐ <code>external:Serpentity.System</code>
+    * [new PhysicsWorldControlSystem(config)](#new_PhysicsWorldControlSystem_new)
+    * [.added(engine)](#PhysicsWorldControlSystem+added)
+    * [.removed()](#PhysicsWorldControlSystem+removed)
+    * [.update(currentFrameDuration)](#PhysicsWorldControlSystem+update)
+
+<a name="new_PhysicsWorldControlSystem_new"></a>
+
+### new PhysicsWorldControlSystem(config)
+Adds and removes objects to the physics world and calls update
+
+
+| Param | Type | Description |
+| --- | --- | --- |
+| config | <code>object</code> | a configuration object to extend. |
+
+<a name="PhysicsWorldControlSystem+added"></a>
+
+### physicsWorldControlSystem.added(engine)
+Initializes system when added. Requests physics nodes and
+attaches to event listeners to add / remove them to pixi stage
+
+**Kind**: instance method of [<code>PhysicsWorldControlSystem</code>](#PhysicsWorldControlSystem)  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| engine | <code>external:Serpentity.Engine</code> | the serpentity engine to which we are getting added |
+
+<a name="PhysicsWorldControlSystem+removed"></a>
+
+### physicsWorldControlSystem.removed()
+Clears system resources when removed.
+
+**Kind**: instance method of [<code>PhysicsWorldControlSystem</code>](#PhysicsWorldControlSystem)  
+<a name="PhysicsWorldControlSystem+update"></a>
+
+### physicsWorldControlSystem.update(currentFrameDuration)
+Runs on every update of the loop. Updates the physics
+
+**Kind**: instance method of [<code>PhysicsWorldControlSystem</code>](#PhysicsWorldControlSystem)  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| currentFrameDuration | <code>Number</code> | the duration of the current frame |
+
+<a name="RenderSystem"></a>
+
+## RenderSystem ⇐ <code>external:Serpentity.System</code>
+**Kind**: global class  
+**Extends**: <code>external:Serpentity.System</code>  
+
+* [RenderSystem](#RenderSystem) ⇐ <code>external:Serpentity.System</code>
+    * [new RenderSystem(config)](#new_RenderSystem_new)
+    * [.added(engine)](#RenderSystem+added)
+    * [.removed()](#RenderSystem+removed)
+    * [.update(currentFrameDuration)](#RenderSystem+update)
+
+<a name="new_RenderSystem_new"></a>
+
+### new RenderSystem(config)
+Renders renderable objects using pixi
+
+
+| Param | Type | Description |
+| --- | --- | --- |
+| config | <code>object</code> | a configuration object to extend. |
+
+<a name="RenderSystem+added"></a>
+
+### renderSystem.added(engine)
+Initializes system when added. Requests renderable nodes and
+attaches to event listeners to add / remove them to pixi stage
+
+**Kind**: instance method of [<code>RenderSystem</code>](#RenderSystem)  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| engine | <code>external:Serpentity.Engine</code> | the serpentity engine to which we are getting added |
+
+<a name="RenderSystem+removed"></a>
+
+### renderSystem.removed()
+Clears system resources when removed.
+
+**Kind**: instance method of [<code>RenderSystem</code>](#RenderSystem)  
+<a name="RenderSystem+update"></a>
+
+### renderSystem.update(currentFrameDuration)
+Runs on every update of the loop. Does nothing.
+
+**Kind**: instance method of [<code>RenderSystem</code>](#RenderSystem)  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| currentFrameDuration | <code>Number</code> | the duration of the current frame |
+
+<a name="PixiFactory"></a>
+
+## PixiFactory : <code>object</code>
+Factory object that contains many methods to create prefab pixi
+objects
+
+**Kind**: global variable  
+
+* [PixiFactory](#PixiFactory) : <code>object</code>
+    * [.createSumo()](#PixiFactory.createSumo) ⇒ <code>external:CreateJs.Container</code>
+    * [.createEmptyGraphic()](#PixiFactory.createEmptyGraphic) ⇒ <code>external:CreateJs.Container</code>
+
+<a name="PixiFactory.createSumo"></a>
+
+### PixiFactory.createSumo() ⇒ <code>external:CreateJs.Container</code>
+Creates a sumo container
+
+**Kind**: static method of [<code>PixiFactory</code>](#PixiFactory)  
+**Returns**: <code>external:CreateJs.Container</code> - the created container  
+<a name="PixiFactory.createEmptyGraphic"></a>
+
+### PixiFactory.createEmptyGraphic() ⇒ <code>external:CreateJs.Container</code>
+Creates an empty graphic
+
+**Kind**: static method of [<code>PixiFactory</code>](#PixiFactory)  
+**Returns**: <code>external:CreateJs.Container</code> - the created container  
+<a name="SumoFactory"></a>
+
+## SumoFactory : <code>object</code>
+Factory object that contains many methods to create prefab entities.
+
+**Kind**: global variable  
+
+* [SumoFactory](#SumoFactory) : <code>object</code>
+    * [.createSumo([engine], [config])](#SumoFactory.createSumo) ⇒ <code>external:Serpentity.Entity</code>
+    * [.createRubberBand([engine], [config])](#SumoFactory.createRubberBand) ⇒ <code>external:Serpentity.Entity</code>
+
+<a name="SumoFactory.createSumo"></a>
+
+### SumoFactory.createSumo([engine], [config]) ⇒ <code>external:Serpentity.Entity</code>
+Creates a sumo entity and adds it to the engine. Can override
+position in the config object
+
+**Kind**: static method of [<code>SumoFactory</code>](#SumoFactory)  
+**Returns**: <code>external:Serpentity.Entity</code> - the created entity  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| [engine] | <code>external:Serpentity</code> | the serpentity engine to attach to. If not sent, it will not be attached. |
+| [config] | <code>object</code> | the config to override the entity, accepts the key `position` as an object with an x and y property. |
+
+<a name="SumoFactory.createRubberBand"></a>
+
+### SumoFactory.createRubberBand([engine], [config]) ⇒ <code>external:Serpentity.Entity</code>
+Creates a rubber band entity and adds it to the engine.
+
+**Kind**: static method of [<code>SumoFactory</code>](#SumoFactory)  
+**Returns**: <code>external:Serpentity.Entity</code> - the created entity  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| [engine] | <code>external:Serpentity</code> | the serpentity engine to attach to. If not sent, it will not be attached. |
+| [config] | <code>object</code> | the config to override the entity, it must include entityA and entityB which will be tied by it. If they are not sent or don't have a physics body, this will throw. |
+