_setDocumentSizes() {
        // set our basic initial infos
        let planeBoundingRect = this.htmlElement.getBoundingClientRect();

        if(!this._boundingRect) this._boundingRect = {};

        // set plane dimensions in document space
        this._boundingRect.document = {
            width: planeBoundingRect.width * this.renderer.pixelRatio,
            height: planeBoundingRect.height * this.renderer.pixelRatio,
            top: planeBoundingRect.top * this.renderer.pixelRatio,
            left: planeBoundingRect.left * this.renderer.pixelRatio,
        };
    }
Set our plane dimensions and positions relative to document
     Triggers reflow!
*