TrackballControls: Fix multi-touch in `onTouchEnd()`. (#24631)

* Fix camera runaway after zoom gesture

problem is observed on mobile phone, when lifting one finger after multitouch gesture, the camera will change dramatically as if swiped from that position to where first finger is

* Update TrackballControls.js

Co-authored-by: Michael Herzog <[email protected]>

examples/jsm/controls/TrackballControls.js

@@ -700,8 +700,20 @@ class TrackballControls extends EventDispatcher {
 
 				case 2:
 					_state = STATE.TOUCH_ZOOM_PAN;
-					_moveCurr.copy( getMouseOnCircle( event.pageX - _movePrev.x, event.pageY - _movePrev.y ) );
-					_movePrev.copy( _moveCurr );
+
+					for ( let i = 0; i < _pointers.length; i ++ ) {
+
+						if ( _pointers[ i ].pointerId !== event.pointerId ) {
+
+							const position = _pointerPositions[ _pointers[ i ].pointerId ];
+							_moveCurr.copy( getMouseOnCircle( position.x, position.y ) );
+							_movePrev.copy( _moveCurr );
+							break;
+
+						}
+
+					}
+
 					break;
 
 			}