SkinnedMesh: support weight normalization for BufferGeometry

src/objects/SkinnedMesh.js

@@ -97,7 +97,7 @@ THREE.SkinnedMesh.prototype.normalizeSkinWeights = function () {
 
 	if ( this.geometry instanceof THREE.Geometry ) {
 
-		for ( var i = 0; i < this.geometry.skinIndices.length; i ++ ) {
+		for ( var i = 0; i < this.geometry.skinWeights.length; i ++ ) {
 
 			var sw = this.geometry.skinWeights[ i ];
 
@@ -109,15 +109,40 @@ THREE.SkinnedMesh.prototype.normalizeSkinWeights = function () {
 
 			} else {
 
-				sw.set( 1 ); // this will be normalized by the shader anyway
+				// do nothing
 
 			}
 
 		}
 
-	} else {
+	} else if ( this.geometry instanceof THREE.BufferGeometry ) {
+
+		var vec = new THREE.Vector4();
+
+		var skinWeight = this.geometry.attributes.skinWeight;
+
+		for ( var i = 0; i < skinWeight.count; i ++ ) {
+
+			vec.x = skinWeight.getX( i );
+			vec.y = skinWeight.getY( i );
+			vec.z = skinWeight.getZ( i );
+			vec.w = skinWeight.getW( i );
+
+			var scale = 1.0 / vec.lengthManhattan();
+
+			if ( scale !== Infinity ) {
 
-		// skinning weights assumed to be normalized for THREE.BufferGeometry
+				vec.multiplyScalar( scale );
+
+			} else {
+
+				// do nothing
+
+			}
+
+			skinWeight.setXYZ( i, vec.x, vec.y, vec.z, vec.w )
+
+		}
 
 	}