Rotate and Scale About a Point

import { Axis } from "@babylonjs/core/Maths/math.axis";
import { Quaternion, Vector3 } from "@babylonjs/core/Maths/math.vector";
import { Mesh } from "@babylonjs/core/Meshes/mesh";
Mesh.prototype.rotateAroundPivot = function (pivotPoint, axis, angle) {
    if (!this._rotationQuaternion) {
        this._rq = Quaternion.RotationYawPitchRoll(this.rotation.y, this.rotation.x, this.rotation.z);
    }
    else
        this._rq = this.rotationQuaternion;
    var _p = new Quaternion(this.position.x - pivotPoint.x, this.position.y - pivotPoint.y, this.position.z - pivotPoint.z, 0);
    axis.normalize();
    var _q = Quaternion.RotationAxis(axis, angle); //form quaternion rotation		
    var _qinv = Quaternion.Inverse(_q);
    var _pdash = _q.multiply(_p).multiply(_qinv);
    this.position = new Vector3(pivotPoint.x + _pdash.x, pivotPoint.y + _pdash.y, pivotPoint.z + _pdash.z);
    this.rotationQuaternion = _q.multiply(this._rq);
};
mesh.rotateAroundPivot(new Vector3(1, 2, -1), new Axis.Y, Math.PI / 4);

import { Vector3 } from "@babylonjs/core/Maths/math.vector";
import { Mesh } from "@babylonjs/core/Meshes/mesh";
Mesh.prototype.scaleFromPivot = function(pivotPoint, sx, sy, sz) {
	var _sx = sx / this.scaling.x;
	var _sy = sy / this.scaling.y;
	var _sz = sz / this.scaling.z;
	this.scaling = new Vector3(sx, sy, sz);	
	this.position = new Vector3(pivotPoint.x + _sx * (this.position.x - pivotPoint.x), pivotPoint.y + _sy * (this.position.y - pivotPoint.y), pivotPoint.z + _sz * (this.position.z - pivotPoint.z));
}

mesh.scaleFromPivotnew Vector3(1, 2, -1), 2, 6, 0.5);