Macro aframe::component_def

macro_rules! component_def {
    ($(dependencies : $($deps : expr), * ;) ? $(schema : $schema : expr,) ?
 $(multiple : $mult : expr,) ? $(init : $init : expr,) ?
 $(update : $update : expr,) ? $(tick : $tick : expr,) ?
 $(tock : $tock : expr,) ? $(remove : $remove : expr,) ?
 $(pause : $pause : expr,) ? $(play : $play : expr,) ?
 $(update_schema : $update_schema : expr,) ?) => { ... };
}

Top-level macro to define components. Usage resembles struct creation syntax. The js! macro is available for writing inline javascript, and returns a js_sys::Function object. This macro calls into on expressions passed into the fields expecting function, allowing the js! macro to be used as a catch-all. Takes the optional fields described in the table below.

field	syntax explanation	description
dependencies	strings separated by commas	names of components that must be initialized prior to this one
schema	A hashmap containing string keys and ComponentProperty values. Recommend the maplit crate	Describes component properties
multiple	boolean value	True to allow multiple components on a single entity
init	JsValue created from a js_sys::Function()	Called on initialization
update	JsValue created from a js_sys::Function(oldData)	Called whenever the component’s properties change
tick	JsValue created from a js_sys::Function(time, timeDelta)	Called called on each tick or frame of the scene’s render loop
tock	JsValue created from a js_sys::Function(time, timeDelta, camera)	Identical to the tick method but invoked after the scene has rendered
remove	JsValue created from a js_sys::Function()	Called whenever the component is detached from the entity
pause	JsValue created from a js_sys::Function()	Called when the entity or scene pauses
play	JsValue created from a js_sys::Function()	Called when the entity or scene resumes
update_schema	JsValue created from a js_sys::Function(data)	if defined, is called on every update in order to check if the schema needs to be dynamically modified

All parameteres are optional, although the order must be exactly as shown. dependencies should be a comma-separated list of strings followed by a semicolon. schema should be a HashMap with string keys and ComponentProperty values. multiple is a boolean value. The rest are strings containing javascript code. A js! macro is provided to allow inline javascript code to be included in the Rust code (See the docs for the js! macro for caveats and limitations). Here’s an example:

// Example: 
let some_component = component_def!
(
    dependencies: "dependency1", "dependency2", some_string,
    schema: hashmap!
    {
        "position" => ComponentProperty::float("number", None),
        "text" => ComponentProperty::string("string", Some(Cow::Borrowed("x"))),
        "autoplay" => ComponentProperty::boolean("boolean", Some(true))
    },
    multiple: true,
    init: js!
    (
        this.radians = Math.PI * 2; 
        this.initalRotation = this.el.object3D.rotation.clone();
    ),
    update: js!(oldData =>> this.rotation = this.el.object3D.rotation;),
    tick: js!
    (time, delta =>>
        if (this.data.autoplay)
        {
            var amount = this.data.radiansPerMillisecond * delta * this.data.speedMult;
            if (this.data.axis.includes('x'))
                this.rotation.x = (this.rotation.x + amount) % this.radians;
            if (this.data.axis.includes('y'))
                this.rotation.y = (this.rotation.y + amount) % this.radians;
            if (this.data.axis.includes('z'))
                this.rotation.z = (this.rotation.z + amount) % this.radians;
        }
    ),
    remove: js!(this.rotation.copy(this.initialRotation);),
    pause: js!(this.data.autoplay = false;),
    play: js!(this.data.autoplay = true;),
);
unsafe
{
    some_component.register("component_name");
}