
## Rotating and Enlarging Relative to a Centre.
The following two code snippets give the opportunity to place a centre of rotation or enlargement, or pivot, at any time and have a mesh rotate or enlarge relative to that centre.


## Rotate
 
```javascript
BABYLON.Mesh.prototype.rotateAroundPivot = function(pivotPoint, axis, angle) {
	if(!this._rotationQuaternion) {
		this._rq = BABYLON.Quaternion.RotationYawPitchRoll(this.rotation.y, this.rotation.x, this.rotation.z);
	}		
	var _p = new BABYLON.Quaternion(this.position.x - pivotPoint.x, this.position.y - pivotPoint.y, this.position.z - pivotPoint.z, 0);
	axis.normalize();
	var _q = BABYLON.Quaternion.RotationAxis(axis,angle);  //form quaternion rotation		
	var _qinv = BABYLON.Quaternion.Inverse(_q);	
	var _pdash = _q.multiply(_p).multiply(_qinv);
	this.position = new BABYLON.Vector3(pivotPoint.x + _pdash.x, pivotPoint.y + _pdash.y, pivotPoint.z + _pdash.z);
	this.rotationQuaternion = this._rq.multiply(_q);
	this._rq = this.rotationQuaternion;
}

mesh.rotateAroundPivot(new BABYLON.Vector3(1, 2, -1), new BABYLON.Axis.Y, Math.PI/4);
```

The parameters are the position of the pivot (centre of rotation) as a Vector3, axis of rotation as a Vector3 and an angle of rotation a number in radians.

Succesive rotations are accumulative.

## Enlargement

```javascript
BABYLON.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 BABYLON.Vector3(sx, sy, sz);	
	this.position = new BABYLON.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 BABYLON.Vector3(1, 2, -1), 2, 6, 0.5);
```

The parameters are the position of the pivot (centre of enlargemen) as a Vector3, scaling in the x, y and z directions as numbers.

## Playground

<Playground id="#1MKHR9#2" title="Rotating and Enlarging Relative to a Centre" description=""/>


## Open an URL with Action Manager

Since any Javascript can be called when executing code action with the action manager it is straight forward to open a new web page using 

```javascript
window.open(URL)
```
to open a new window or

```javascript
window.location = URL
```
to replace the contants of the current window.

<Playground id="#INB624#1" title="Open URL On Single Mesh Click" description=""/>
<Playground id="#INB624#2" title="Open URL On Mesh Click Of Multiple Meshes" description=""/>

Display Tangent, Normal, and Binormal of a Path3D

Displays a Path3D Curve.

Playground