Fix: expose AttributeOptions

[ivanpopelyshev]

The problem in existing project:

For v7 I always overrode geometry attributes in constructor:

class MyGeom extends Geometry {
    constructor() {
         this.buffer = new Buffer();
         this.addAttribute();
    }
}

and that evolved to function that just takes care of buffer:

class MyGeom extends Geometry {
    constructor() {
         this.buffer = new Buffer();
         this.initGeom();
    }
    initGeom() {
         this.addAttribute();
    }
}

initGeom() can also used for similar geometries that have same attribute list, but completely different set of fields, i just call MyGeom.prototype.initGeom.call(this)

know this approach is not possible because attributes has to be passed to super(). Thus, I have to

class MyGeom extends Geometry {
    constructor() {
         const buffer = new Buffer();
         super({ BIG_F_ATTRIBUTE_LIST })
         this.buffer=buffer;
    }
}

that's certainly not ok , so I added function, again:

class MyGeom extends Geometry {
    constructor() {
         const buffer = new Buffer();
         super({ attributes: initGeom(buf) });
    }
    static initGeom(buf: Buffer): AttributeOptions {
         return { a_attr1: {} , a_attr2: {}, }
    }
}

thus, initGeom can be used for other geometry classes.

However, that is not passing through typescript, I need AttributeOptions exposed to set the type of initGeom manually, it cannot be infered!

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit ac9103a:

Sandbox	Source
pixi.js-sandbox	Configuration