Better usemtl handling

CHANGES.md

@@ -1,6 +1,10 @@
 Change Log
 ==========
 
+### 2.2.0 ???
+
+* Fixed handling of `usemtl` when appearing before an `o` or `g` token. [#121](https://github.com/AnalyticalGraphicsInc/obj2gltf/pull/121)
+
 ### 2.1.0 2017-12-28
 
 * Fixed loading faces that contain less than 3 vertices. [#120](https://github.com/AnalyticalGraphicsInc/obj2gltf/pull/120)

lib/loadObj.js

@@ -71,6 +71,7 @@ function loadObj(objPath, options) {
     var node;
     var mesh;
     var primitive;
+    var activeMaterial;
 
     // All nodes seen in the obj
     var nodes = [];
@@ -120,12 +121,15 @@ function loadObj(objPath, options) {
 
     function addPrimitive() {
         primitive = new Primitive();
+        primitive.material = activeMaterial;
         mesh.primitives.push(primitive);
     }
 
     function useMaterial(name) {
-        // Look to see if this material has already been used by a primitive in the mesh
         var material = getName(name);
+        activeMaterial = material;
+
+        // Look to see if this material has already been used by a primitive in the mesh
         var primitives = mesh.primitives;
         var primitivesLength = primitives.length;
         for (var i = 0; i < primitivesLength; ++i) {
@@ -136,7 +140,6 @@ function loadObj(objPath, options) {
         }
         // Add a new primitive with this material
         addPrimitive();
-        primitive.material = getName(name);
     }
 
     function getOffset(a, attributeData, components) {
@@ -533,6 +536,12 @@ function finishLoading(nodes, mtlPaths, objPath, options) {
 function loadMtls(mtlPaths, objPath, options) {
     var objDirectory = path.dirname(objPath);
     var materials = [];
+
+    // Remove duplicates
+    mtlPaths = mtlPaths.filter(function(value, index, self) {
+        return self.indexOf(value) === index;
+    });
+
     return Promise.map(mtlPaths, function(mtlPath) {
         mtlPath = path.resolve(objDirectory, mtlPath);
         var shallowPath = path.resolve(path.join(objDirectory, path.basename(mtlPath)));