Merge pull request #14517 from WestLangley/dev-lookAt

Object3D.lookAt(): support rotated parents

src/core/Object3D.js

@@ -303,35 +303,51 @@ Object3D.prototype = Object.assign( Object.create( EventDispatcher.prototype ),
 
 	lookAt: function () {
 
-		// This method does not support objects with rotated and/or translated parent(s)
+		// This method does not support objects having non-uniformly-scaled parent(s)
 
+		var q1 = new Quaternion();
 		var m1 = new Matrix4();
-		var vector = new Vector3();
+		var target = new Vector3();
+		var position = new Vector3();
 
 		return function lookAt( x, y, z ) {
 
 			if ( x.isVector3 ) {
 
-				vector.copy( x );
+				target.copy( x );
 
 			} else {
 
-				vector.set( x, y, z );
+				target.set( x, y, z );
 
 			}
 
+			var parent = this.parent;
+
+			this.updateWorldMatrix( true, false );
+
+			position.setFromMatrixPosition( this.matrixWorld );
+
 			if ( this.isCamera ) {
 
-				m1.lookAt( this.position, vector, this.up );
+				m1.lookAt( position, target, this.up );
 
 			} else {
 
-				m1.lookAt( vector, this.position, this.up );
+				m1.lookAt( target, position, this.up );
 
 			}
 
 			this.quaternion.setFromRotationMatrix( m1 );
 
+			if ( parent ) {
+
+				m1.extractRotation( parent.matrixWorld );
+				q1.setFromRotationMatrix( m1 );
+				this.quaternion.premultiply( q1.inverse() );
+
+			}
+
 		};
 
 	}(),
@@ -611,6 +627,44 @@ Object3D.prototype = Object.assign( Object.create( EventDispatcher.prototype ),
 
 	},
 
+	updateWorldMatrix: function ( updateParents, updateChildren ) {
+
+		var parent = this.parent;
+
+		if ( updateParents === true && parent !== null ) {
+
+			parent.updateWorldMatrix( true, false );
+
+		}
+
+		if ( this.matrixAutoUpdate ) this.updateMatrix();
+
+		if ( this.parent === null ) {
+
+			this.matrixWorld.copy( this.matrix );
+
+		} else {
+
+			this.matrixWorld.multiplyMatrices( this.parent.matrixWorld, this.matrix );
+
+		}
+
+		// update children
+
+		if ( updateChildren === true ) {
+
+			var children = this.children;
+
+			for ( var i = 0, l = children.length; i < l; i ++ ) {
+
+				children[ i ].updateWorldMatrix( false, true );
+
+			}
+
+		}
+
+	},
+
 	toJSON: function ( meta ) {
 
 		// meta is a string when called from JSON.stringify