ArcballControls: Fix drifting when zooming with the mouse cursor

[Tirzono]

Description

The intention of passing in this._gizmos.position to this.scale is to scale around the gizmo position. This means that in this.scale the _scalePointTemp should be (0, 0, 0), and the camera position translation should result in (0, 0, 0) as well. However, there are situations where this does not happen and that's when the this._gizmos.position gets updated. Because in this.scale this happens:

_scalePointTemp.copy( point );

[...]

this._v3_1.setFromMatrixPosition( this._gizmoMatrixState );	//gizmos position

[...]

_scalePointTemp.sub( this._v3_1 );

const amount = _scalePointTemp.clone().multiplyScalar( sizeInverse );
_scalePointTemp.sub( amount );

this._m4_1.makeTranslation( _scalePointTemp.x, _scalePointTemp.y, _scalePointTemp.z );

This means that if this._gizmos.position and this._gizmoMatrixState are out-of-sync, a translation happens which propagates and causes the camera position to drift and at some point grow massively.

By passing in the position coming from this._gizmoMatrixState this issue would be resolved.

Note that in other calls to this.scale where this._gizmos.position is passed we always call updateTbState, which syncs the this._gizmos.position and this._gizmoMatrixState (I tried to do that here as well, but it causes an issue with zooming, probably because it would also update this._zoomState and the function doesn't expect that).

[mrdoob]

@danielefornari @cignoni looks good?

[danielefornari]

Sounds ok to me

[mrdoob]

Thanks!