Improve Object3D add and remove

src/core/Object3D.js

@@ -332,10 +332,11 @@ Object.assign( Object3D.prototype, EventDispatcher.prototype, {
 			}
 
 			object.parent = this;
-			object.dispatchEvent( { type: 'added' } );
-
 			this.children.push( object );
 
+			object.dispatchEvent( { type: 'added' } );
+			this.dispatchEvent( { type: 'childAdded', child: object } );
+
 		} else {
 
 			console.error( "THREE.Object3D.add: object not an instance of THREE.Object3D.", object );
@@ -363,10 +364,10 @@ Object.assign( Object3D.prototype, EventDispatcher.prototype, {
 		if ( index !== - 1 ) {
 
 			object.parent = null;
+			this.children.splice( index, 1 );
 
 			object.dispatchEvent( { type: 'removed' } );
-
-			this.children.splice( index, 1 );
+			this.dispatchEvent( { type: 'childRemoved', child: object } );
 
 		}
 

test/unit/src/core/Object3D.js

@@ -80,3 +80,53 @@ QUnit.test( "getWorldRotation" , function( assert ) {
 	obj.lookAt(new THREE.Vector3(1, 0, 0));
 	assert.numEqual( obj.getWorldRotation().y * RadToDeg, 90, "y is equal" );
 });
+
+QUnit.test( "add" , function( assert ) {
+	assert.expect( 16 );
+
+	var parent = new THREE.Object3D();
+	var child = new THREE.Object3D();
+
+	function parentAdd( evt ) {
+		assert.success( "parent dispatches 'childAdded' event when adding a child" );
+		assert.strictEqual( evt.child, child, "childAdded event passes child object" );
+		assert.strictEqual( parent.children[0], child, "parent has child when 'add' event dispatched" );
+		assert.strictEqual( parent, child.parent, "child has parent when 'add' event dispatched" );
+	}
+
+	function parentRemove( evt ) {
+		assert.success( "parent dispatches 'childRemoved' event when removing a child" );
+		assert.strictEqual( evt.child, child, "childRemoved event passes child object" );
+		assert.strictEqual( parent.children.length, 0, "child removed from parent when 'remove' event dispatched" );
+		assert.strictEqual( child.parent, null, "child has no parent when 'remove' event dispatched" );
+	}
+
+	function childAdd() {
+		assert.success( "child dispatches 'added' event when adding to a parent object" );
+		assert.strictEqual( parent.children[0], child, "parent has child when 'added' event dispatched" );
+		assert.strictEqual( parent, child.parent, "child has parent when 'added' event dispatched" );
+	}
+
+	function childRemove() {
+		assert.success( "child dispatches 'removed' event when removing from parent" );
+		assert.strictEqual( parent.children.length, 0, "child removed from parent when 'removed' event dispatched" );
+		assert.strictEqual( child.parent, null, "child has no parent when 'removed' event dispatched" );
+	}
+
+	parent.addEventListener( "childAdded", parentAdd );
+	parent.addEventListener( "childRemoved", parentRemove );
+	child.addEventListener( "added", childAdd );
+	child.addEventListener( "removed", childRemove );
+
+	parent.add( child );
+	assert.strictEqual( parent.children[0], child, "parent has child after parent.add( child )" );
+	assert.strictEqual( parent, child.parent, "child has parent after parent.add( child )" );
+
+	parent.remove( child );
+
+	// clean up
+	parent.removeEventListener( "childAdded", parentAdd );
+	parent.removeEventListener( "childRemoved", parentRemove );
+	child.removeEventListener( "add", childAdd );
+	child.removeEventListener( "removed", childRemove );
+});