ArcballControls: Expose raycaster.

[Tirzono]

Description

This allows users to use their own raycaster (that has for example certain layers enabled/disabled). Since unprojectOnObj is used for the double click to focus functionality, passing in your own raycaster is useful if you want the double click to focus functionality also to work on objects that are in different layers.

[Mugen87]

@danielefornari Looking good?

[danielefornari]

Yeah, sounds good!

[mrdoob]

We should probably follow #22070 and add a getRaycaster() instead.

[Tirzono]

I am okay doing that change because I can achieve what I want with that as well by extending the ArcballControls and overwrite the getRaycaster method:

class ExtendedArcballControls extends ArcballControls {
    constructor(...args) {
        super(...args);

        this.raycaster = new Raycaster();
    }

    getRaycaster() {
        return this.raycaster;
    }
}

Another possible solution would be to do something like this in my code:

const controls = new ArcballControls();
const raycaster = controls.getRaycaster();

raycaster.layers.enable(4); // For example

However, I have multiple canvases on one page and if I would use multiple ArcballControls on one page as well they all share the same raycaster and this might not be what I want (because in one canvas I want layers 4 to be enabled and in the other one maybe not). Is this something we take into account?

Let me know what you think. It's more a question, I am happy to make the change because I can achieve what I want with the first example that I gave.

[Mugen87]

It's just a matter of consistency. Instead of exposing raycaster as a property, it's better to expose it via a getter.

Sharing the same raycaster across multiple control instances is a different matter though. I would not adding support for this since I'm afraid there are unexpected side effects. Hence, the raycaster reference of the control class should not be writable by the application.

[Tirzono]

Sharing the same raycaster across multiple control instances is a different matter though. I would not adding support for this since I'm afraid there are unexpected side effects.

But isn't this not the case when we would use the getRaycaster method? At least, if I look at the code in TransformControsl, it is sharing the same raycaster across multiple control instances:

const first = new TransformControls(
  new OrthographicCamera(),
  document.createElement("canvas")
);
const second = new TransformControls(
  new OrthographicCamera(),
  document.createElement("canvas")
);

first.getRaycaster() === second.getRaycaster() // equals true

https://codesandbox.io/s/interesting-rubin-owq9j?file=/src/index.js

Should I not follow that example and make a this._raycaster so that we have a unique raycaster per ArcballControls instance and return that with getRaycaster?

[Mugen87]

Oh right, that's true. If forgot that TransformControls(and DragControls) define their raycaster in module scope.

I guess it would be good to do the same for ArcballControls if possible.

[Tirzono]

That's done now 😃

[mrdoob]

Thanks!