管理Threejs Geometry的元数据

Question

I have Metadata for my three.js geometries. What is the best way to link this Metadata, as there is no Attribute where I would be able to store it directly in the Object itself?

Answer 1

You can store user data in the Object.userData object.

edit: It's been pointed out that Geometries don't have a userData...

But userData can still be used and will be serialized, so perhaps something along the lines of

myScene.userData.geometryMetas={}
and then populate with myScene.userData.geometryMetas[geometry.uuid]=YourMetaData

Answer 2

You have three options.

1. Monkey patching

Just add the Attribute property directly to the three.js object.

var myGeom = new THREE.Geometry();
myGeom.Attributes = Metadata;

This has the advantage of being quick and easy. It has the disadvantages of being hacky and somewhat fragile (as monkey patching always is), and the metadata won't be included in the Geometry's toJSON() method, which may or may not be what you want.

2. Wrapping

Just wrap the geometry in a new object with its own Attributes property. You can use a plain object:

var myGeom = {
    geometry: new THREE.Geometry(),
    attributes: Metadata
};

or create a constructor:

function MyGeom(geometry, attributes) {
    this.geometry = geometry;
    this.attributes = attributes;
}
var myGeom = new MyGeom(new THREE.Geometry, Metadata);

The disadvantage is that everywhere that you would have simply carried around THREE.Geometry objects, you now have to use the wrapped objects, and unwrap them when it's time to call into the Three.js API, and re-wrap anything you get out of it.

3. Keep Metadata separate

Every THREE.Geometry object has a unique uuid property. You can use this uuid as the key in a separate metadata object and still just work with regular Three.js objects.

var AllMetadata = {}; // Should be global or assigned to a project namespace
var myGeom = new THREE.Geometry();
AllMetadata[myGeom.uuid] = Metadata;

This way you don't have to pass around your attribute data with the geometries, but it's available when you do need it.