Object bounding box relative to given reference

src/math/Box3.js

@@ -1,5 +1,6 @@
 import { Vector3 } from './Vector3';
 import { Sphere } from './Sphere';
+import { Matrix4 } from './Matrix4';
 
 /**
  * @author bhouston / http://clara.io
@@ -123,12 +124,12 @@ Object.assign( Box3.prototype, {
 
 	}(),
 
-	setFromObject: function ( object ) {
-
+	setFromObject: function (object, reference, excludeInvisibleObjects) {
+		
 		this.makeEmpty();
 
-		return this.expandByObject( object );
-
+		return this.expandByObject( object, reference, excludeInvisibleObjects );
+		
 	},
 
 	clone: function () {
@@ -204,36 +205,62 @@ Object.assign( Box3.prototype, {
 
 	},
 
-	expandByObject: function () {
-
-		// Computes the world-axis-aligned bounding box of an object (including its children),
-		// accounting for both the object's, and children's, world transforms
-
+	expandByObject: function (object, ref, excludeInvisibleObjects) {
+		// Computes the bounding box of an object (including its children) in the given reference object's coordinate system, or world coordinates if no reference is specified,
+		// accounting for both the object's, and children's, transforms.
+		// excludeInvisibleObjects specifies whether to use traverseVisible instead of traverse.
+			var trans;
+
+			if (ref !== undefined) {
+
+				trans = new Matrix4().getInverse(ref.matrixWorld);
+
+			}
+
+			this.expandByTransformedObject(object, trans, excludeInvisibleObjects);
+	},
+	expandByTransformedObject: function () {
+
+		// Computes the bounding box of an object (including its children)in the coordinate system given by trans,
+		// or world coordinates if no trans is specified,
+		// accounting for both the object's, and children's, transforms.
+		// excludeInvisibleObjects specifies whether to use traverseVisible instead of traverse.
+
 		var v1 = new Vector3();
+		var m1 = new Matrix4();
 
-		return function expandByObject( object ) {
-
+		return function expandByObject( object, trans, excludeInvisibleObjects ) {
+			
 			var scope = this;
 
 			object.updateMatrixWorld( true );
-
-			object.traverse( function ( node ) {
+			
+			object["traverse"+(excludeInvisibleObjects ? "Visible" : "")]( function ( node ) {
 
 				var i, l;
+
+				if (trans !== undefined) {
+
+					m1.multiplyMatrices(trans, node.matrixWorld);
+
+				} else {
+
+					m1.copy(node.matrixWorld);
+
+				}
 
 				var geometry = node.geometry;
 
 				if ( geometry !== undefined ) {
-
+					
 					if ( geometry.isGeometry ) {
 
 						var vertices = geometry.vertices;
 
 						for ( i = 0, l = vertices.length; i < l; i ++ ) {
 
 							v1.copy( vertices[ i ] );
-							v1.applyMatrix4( node.matrixWorld );
-
+							v1.applyMatrix4( m1 );
 							scope.expandByPoint( v1 );
 
 						}
@@ -246,10 +273,9 @@ Object.assign( Box3.prototype, {
 
 							for ( i = 0, l = attribute.count; i < l; i ++ ) {
 
-								v1.fromBufferAttribute( attribute, i ).applyMatrix4( node.matrixWorld );
-
+								v1.fromBufferAttribute( attribute, i ).applyMatrix4( m1 );
 								scope.expandByPoint( v1 );
-
+								
 							}
 
 						}