Material: Fixed normalMapType serialisation/deserialisation.

src/loaders/MaterialLoader.js

@@ -124,6 +124,7 @@ Object.assign( MaterialLoader.prototype, {
 		if ( json.bumpScale !== undefined ) material.bumpScale = json.bumpScale;
 
 		if ( json.normalMap !== undefined ) material.normalMap = getTexture( json.normalMap );
+		if ( json.normalMapType !== undefined ) material.normalMapType = json.normalMapType;
 		if ( json.normalScale !== undefined ) {
 
 			var normalScale = json.normalScale;

src/materials/Material.js

 import { EventDispatcher } from '../core/EventDispatcher.js';
-import { NoColors, FrontSide, FlatShading, NormalBlending, LessEqualDepth, AddEquation, OneMinusSrcAlphaFactor, SrcAlphaFactor, TangentSpaceNormalMap } from '../constants.js';
+import { NoColors, FrontSide, FlatShading, NormalBlending, LessEqualDepth, AddEquation, OneMinusSrcAlphaFactor, SrcAlphaFactor } from '../constants.js';
 import { _Math } from '../math/Math.js';
 
 /**
@@ -194,7 +194,7 @@ Material.prototype = Object.assign( Object.create( EventDispatcher.prototype ),
 		if ( this.normalMap && this.normalMap.isTexture ) {
 
 			data.normalMap = this.normalMap.toJSON( meta ).uuid;
-			if ( this.normalMapType !== TangentSpaceNormalMap ) data.normalMapType = this.normalMapType;
+			data.normalMapType = this.normalMapType;
 			data.normalScale = this.normalScale.toArray();
 
 		}