Mirror Engine
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Mirror Engine API


Mirror Engine API / Script

Class: Script

The Script class is the fundamental base class for all scripts within Mirror Engine. It provides the minimal interface required for a script to run.

At its core, a script is simply a collection of methods that are called at various points in the Engine's lifecycle. These methods are:

Script#initialize - Called once when the script is initialized Script#postInitialize - Called once after all scripts have been initialized Script#update - Called every frame, if the script is enabled Script#postUpdate - Called every frame, after all scripts have been updated Script#swap - Called when a script is redefined

These methods are entirely optional, but provide a useful way to manage the lifecycle of a script and perform any necessary setup and cleanup.

Below is a simple example of a script that rotates an entity every frame.

Example

class EntityRotator extends Script {
  update() {
    this.entity.rotateLocal(0, 1, 0)
  }
}

When this script is attached to an entity, the update will be called every frame, slowly rotating the entity around the Y-axis.

Extends

Properties

app

app: AppBase

The AppBase that the instance of this type belongs to.


entity

entity: Entity

The Entity that the instance of this type belongs to.

enabled

Set Signature

set enabled(value: any): void

True if the instance of this type is in running state. False when script is not running, because the Entity or any of its parents are disabled or the ScriptComponent is disabled or the Script Instance is disabled. When disabled no update methods will be called on each tick. initialize and postInitialize methods will run once when the script instance is in enabled state during app tick.

Parameters
value

any

Returns

void


scriptName

Get Signature

get static scriptName(): null | string

Name of a Script Type.

Returns

null | string

Methods

fire()

fire(
   name: string,
   arg1?: any,
   arg2?: any,
   arg3?: any,
   arg4?: any,
   arg5?: any,
   arg6?: any,
   arg7?: any,
   arg8?: any): EventHandler

Fire an event, all additional arguments are passed on to the event listener.

Parameters

name

string

Name of event to fire.

arg1?

any

First argument that is passed to the event handler.

arg2?

any

Second argument that is passed to the event handler.

arg3?

any

Third argument that is passed to the event handler.

arg4?

any

Fourth argument that is passed to the event handler.

arg5?

any

Fifth argument that is passed to the event handler.

arg6?

any

Sixth argument that is passed to the event handler.

arg7?

any

Seventh argument that is passed to the event handler.

arg8?

any

Eighth argument that is passed to the event handler.

Returns

EventHandler

Self for chaining.

Example

obj.fire('test', 'This is the message')

Inherited from

EventHandler.fire


hasEvent()

hasEvent(name: string): boolean

Test if there are any handlers bound to an event name.

Parameters

name

string

The name of the event to test.

Returns

boolean

True if the object has handlers bound to the specified event name.

Example

obj.on('test', () => {}) // bind an event to 'test'
obj.hasEvent('test') // returns true
obj.hasEvent('hello') // returns false

Inherited from

EventHandler.hasEvent


off()

off(
   name?: string,
   callback?: HandleEventCallback,
   scope?: any): EventHandler

Detach an event handler from an event. If callback is not provided then all callbacks are unbound from the event, if scope is not provided then all events with the callback will be unbound.

Parameters

name?

string

Name of the event to unbind.

callback?

HandleEventCallback

Function to be unbound.

scope?

any

Scope that was used as the this when the event is fired.

Returns

EventHandler

Self for chaining.

Example

const handler = () => {}
obj.on('test', handler)

obj.off() // Removes all events
obj.off('test') // Removes all events called 'test'
obj.off('test', handler) // Removes all handler functions, called 'test'
obj.off('test', handler, this) // Removes all handler functions, called 'test' with scope this

Inherited from

EventHandler.off


on()

on(
   name: string,
   callback: HandleEventCallback,
   scope?: any): EventHandle

Attach an event handler to an event.

Parameters

name

string

Name of the event to bind the callback to.

callback

HandleEventCallback

Function that is called when event is fired. Note the callback is limited to 8 arguments.

scope?

any = ...

Object to use as 'this' when the event is fired, defaults to current this.

Returns

EventHandle

Can be used for removing event in the future.

Examples

obj.on('test', (a, b) => {
  console.log(a + b)
})
obj.fire('test', 1, 2) // prints 3 to the console
const evt = obj.on('test', (a, b) => {
  console.log(a + b)
})
// some time later
evt.off()

Inherited from

EventHandler.on


once()

once(
   name: string,
   callback: HandleEventCallback,
   scope?: any): EventHandle

Attach an event handler to an event. This handler will be removed after being fired once.

Parameters

name

string

Name of the event to bind the callback to.

callback

HandleEventCallback

Function that is called when event is fired. Note the callback is limited to 8 arguments.

scope?

any = ...

Object to use as 'this' when the event is fired, defaults to current this.

Returns

EventHandle

  • can be used for removing event in the future.

Example

obj.once('test', (a, b) => {
  console.log(a + b)
})
obj.fire('test', 1, 2) // prints 3 to the console
obj.fire('test', 1, 2) // not going to get handled

Inherited from

EventHandler.once

Events

EVENT_ATTR

static EVENT_ATTR: string = 'attr';

Fired when script attributes have changed. This event is available in two forms. They are as follows:

  1. attr - Fired for any attribute change. The handler is passed the name of the attribute that changed, the value of the attribute before the change and the value of the attribute after the change.
  2. attr:[name] - Fired for a specific attribute change. The handler is passed the value of the attribute before the change and the value of the attribute after the change.

Examples

export class PlayerController extends Script {
  initialize() {
    this.on('attr', (name, newValue, oldValue) => {
      console.log(
        `Attribute '${'${name}'}' changed from '${'${oldValue}'}' to '${'${newValue}'}'`
      )
    })
  }
}
export class PlayerController extends Script {
  initialize() {
    this.on('attr:speed', (newValue, oldValue) => {
      console.log(
        `Attribute 'speed' changed from '${'${oldValue}'}' to '${'${newValue}'}'`
      )
    })
  }
}

EVENT_DESTROY

static EVENT_DESTROY: string = 'destroy';

Fired when a script instance is destroyed and removed from component.

Example

export class PlayerController extends Script {
  initialize() {
    this.on('destroy', () => {
      // no longer part of the entity
      // this is a good place to clean up allocated resources used by the script
    })
  }
}

EVENT_DISABLE

static EVENT_DISABLE: string = 'disable';

Fired when a script instance becomes disabled.

Example

export class PlayerController extends Script {
  initialize() {
    this.on('disable', () => {
      // Script Instance is now disabled
    })
  }
}

EVENT_ENABLE

static EVENT_ENABLE: string = 'enable';

Fired when a script instance becomes enabled.

Example

export class PlayerController extends Script {
  initialize() {
    this.on('enable', () => {
      // Script Instance is now enabled
    })
  }
}

EVENT_ERROR

static EVENT_ERROR: string = 'error';

Fired when a script instance had an exception. The script instance will be automatically disabled. The handler is passed an Error object containing the details of the exception and the name of the method that threw the exception.

Example

export class PlayerController extends Script {
  initialize() {
    this.on('error', (err, method) => {
      // caught an exception
      console.log(err.stack)
    })
  }
}

EVENT_STATE

static EVENT_STATE: string = 'state';

Fired when a script instance changes state to enabled or disabled. The handler is passed a boolean parameter that states whether the script instance is now enabled or disabled.

Example

export class PlayerController extends Script {
  initialize() {
    this.on('state', (enabled) => {
      console.log(`Script Instance is now ` + enabled)
    })
  }
}
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