Query - Documentation

new Query(opts)

Source:

Query.js, line 6

Used to perform matching of entities.

Example

//matches entities with 'Position' and 'Velocity' components
const q1 = Query({
  criterions: ["Position", "Velocity"],
});

//matches entities with 'Position' and 'Velocity' components and without 'Sprite' component
const q2 = Query({
  criterions: {
    include: ["Position", "Velocity"],
    exclude: ["Sprite"],
  },
});

//matches entities of type 'Ball'
const q3 = Query({
  criterions: {
    entityType: "Ball",
  },
});

Parameters:

Name Type Description

opts

Object

Properties

Name	Type	Description
`criterions`	Object \| Array	query criterions

Methods

addToIndex(entityId)

Source:

Query.js, line 143

Adds entity ID to query index.

Parameters:

Name	Type	Description
`entityId`	Number

getEntities() → {Object}

Source:

Query.js, line 171

Returns entities matched by query.

Returns object with following properties:

length - number of matched entities
entities - array with matched entities. This array length is usually not the same as matched entities number!

Returns:

Type: Object

initialize(allEntities)

Source:

Query.js, line 86

Initializes query. Builds initial entities index.

Parameters:

Name	Type	Description
`allEntities`	FastArray	fast array of all entities present in the engine

removeFromIndex(entityId)

Source:

Query.js, line 155

Removes entity ID from query index.

Parameters:

Name	Type	Description
`entityId`	Number

satisfiedBy(entity)

Source:

Query.js, line 105

Checks if entity satisfies query criterions.

Parameters:

Name	Type	Description
`entity`	Entity	entity to check

shouldUpdate()

Source:

Query.js, line 130

Checks if query should update.

Query should update when entities matching its criterions are added or removed from engine. It should also update when entity that was matching criterions has changed and doesn't match it anymore.

update(allEntities)

Source:

Query.js, line 187

Updates internal matched entities with index.

Parameters:

Name	Type	Description
`allEntities`	FastArray	fast array of all entities present in the engine