Class: Physics2DSystem

Unity-style 2D physics over a pluggable IPhysics2DBackend. Runs in Update — the fixed step — after scripts, animation, tweens and schedules, so what they did this tick is simulated this tick. Each step:

1. links components to bodies / fixtures / joints (creating, rebuilding, dropping),
2. picks up transform edits (a static body follows its transform; a dynamic one is teleported; a kinematic one is driven there so it pushes what's in the way),
3. steps the world and dispatches the contact / trigger / joint-break events. Physics2DPoseSystem (PreRender) then writes the simulated poses into the world transforms.

It owns dirty on Rigidbody2D, the colliders and the joints. Nothing exists outside a run: in the editor's edit mode the Update phase is detached, so OnStart / OnStop bound the world.

Extends

• System

Implements

• IContactListener2D

Constructors

Constructor

new Physics2DSystem(): Physics2DSystem;

Returns

Physics2DSystem

Inherited from

System.constructor

Properties

Property	Modifier	Type	Default value	Inherited from
enabled	public	boolean	true	System.enabled
parallel	public	boolean	false	System.parallel

Accessors

autoSimulation

Get Signature

get autoSimulation(): boolean;

Returns

boolean

Set Signature

set autoSimulation(v): void;

Parameters

Parameter	Type
v	boolean

Returns

void

Methods

GetBackend()

GetBackend(): 
  | IPhysics2DBackend
  | null;

Returns

| IPhysics2DBackend | null

---

GetLayersCollide()

GetLayersCollide(a, b): boolean;

Parameters

Parameter	Type
a	number
b	number

Returns

boolean

---

GetName()

GetName(): string;

Returns

string

Overrides

System.GetName

---

GetOrder()

GetOrder(): SystemOrder;

Ordered: what they moved this tick is simulated this tick.

Returns

SystemOrder

---

GetPhase()

GetPhase(): SystemPhase;

Returns

SystemPhase

Overrides

System.GetPhase

---

GetSettings()

GetSettings(): Readonly<Physics2DSettings>;

Returns

Readonly<Physics2DSettings>

---

GetSimulatedEntities()

GetSimulatedEntities(out): number[];

Entities with a simulated body — the editor marks them.

Parameters

Parameter	Type
out	number[]

Returns

number[]

---

IsSimulating()

IsSimulating(): boolean;

A world exists — a run with a backend.

Returns

boolean

---

OnBeginContact()

OnBeginContact(
   a, 
   b, 
   m
): void;

Can arrive mid-step: record, don't touch the world.

Parameters

Parameter	Type
a	IPhysicsFixture2D
b	IPhysicsFixture2D
m	Contact2DManifold

Returns

void

Implementation of

IContactListener2D.OnBeginContact

---

OnClose()

OnClose(): void;

Returns

void

Inherited from

System.OnClose

---

OnEndContact()

OnEndContact(a, b): void;

Parameters

Parameter	Type
a	IPhysicsFixture2D
b	IPhysicsFixture2D

Returns

void

Implementation of

IContactListener2D.OnEndContact

---

OnInit()

OnInit(_engine): void;

Parameters

Parameter	Type
_engine	IEngine

Returns

void

Inherited from

System.OnInit

---

OnRender()

OnRender(_scene, _renderer): void | Promise<void>;

Parameters

Parameter	Type
_scene	Scene
_renderer	IRenderer

Returns

void | Promise<void>

Inherited from

System.OnRender

---

OnRendererChanged()

OnRendererChanged(_renderer): void;

Parameters

Parameter	Type
_renderer	IRenderer

Returns

void

Inherited from

System.OnRendererChanged

---

OnStart()

OnStart(scene, _renderer): void;

Parameters

Parameter	Type
scene	Scene
_renderer	IRenderer

Returns

void

Overrides

System.OnStart

---

OnStop()

OnStop(_scene): void;

Parameters

Parameter	Type
_scene	Scene

Returns

void

Overrides

System.OnStop

---

OnUpdate()

OnUpdate(scene, dt): void;

---------- Tick ---------- Timed as Physics for the stats overlay; contact callbacks into scripts count as Scripts.

Parameters

Parameter	Type
scene	Scene
dt	number

Returns

void

Overrides

System.OnUpdate

---

OverlapPoint()

OverlapPoint(
   x, 
   y, 
   layerMask, 
   all
): Collider2DComponent[];

Parameters

Parameter	Type
x	number
y	number
layerMask	number
all	boolean

Returns

Collider2DComponent[]

---

OverlapShape()

OverlapShape(
   shape, 
   x, 
   y, 
   angle, 
   layerMask, 
   all
): Collider2DComponent[];

Parameters

Parameter	Type
shape	Shape2D
x	number
y	number
angle	number
layerMask	number
all	boolean

Returns

Collider2DComponent[]

---

Override()

Override(partial): void;

This run only (Game.physics2D) — ResetOverrides goes back to the project's.

Parameters

Parameter	Type
partial	Partial<Physics2DSettings>

Returns

void

---

Raycast()

Raycast(
   ox, 
   oy, 
   dx, 
   dy, 
   distance, 
   layerMask
): RaycastHit2D | null;

Parameters

Parameter	Type
ox	number
oy	number
dx	number
dy	number
distance	number
layerMask	number

Returns

RaycastHit2D | null

---

RaycastAll()

RaycastAll(
   ox, 
   oy, 
   dx, 
   dy, 
   distance, 
   layerMask
): RaycastHit2D[];

Parameters

Parameter	Type
ox	number
oy	number
dx	number
dy	number
distance	number
layerMask	number

Returns

RaycastHit2D[]

---

ResetOverrides()

ResetOverrides(): void;

Returns

void

---

SetBackend()

SetBackend(backend): void;

---------- Configuration ---------- null switches physics off: bodies are dropped and the components sit idle.

Parameters

Parameter	Type
backend	| IPhysics2DBackend | null

Returns

void

---

SetGravity()

SetGravity(x, y): void;

Parameters

Parameter	Type
x	number
y	number

Returns

void

---

SetLayersCollide()

SetLayersCollide(
   a, 
   b, 
   collide
): void;

Parameters

Parameter	Type
a	number
b	number
collide	boolean

Returns

void

---

SetSettings()

SetSettings(partial): void;

Parameters

Parameter	Type
partial	Partial<Physics2DSettings>

Returns

void

---

Simulate()

Simulate(dt): void;

Steps the world by dt seconds now — with autoSimulation off, a script drives physics.

Parameters

Parameter	Type
dt	number

Returns

void

---

WritePoses()

WritePoses(scene, alpha): void;

---------- Pose pass (Physics2DPoseSystem) ---------- Writes each moving body's pose — interpolated by alpha (0..1 between the last two steps) when its Rigidbody2D interpolates — into its entity's world transform.

Parameters

Parameter	Type
scene	Scene
alpha	number

Returns

void