Handle face signature containing attributes that are missing

lib/loadObj.js

@@ -189,7 +189,7 @@ function loadObj(objPath, options) {
 
     function createVertex(p, u, n) {
         // Positions
-        if (defined(p)) {
+        if (defined(p) && (globalPositions.length > 0)) {
             const px = globalPositions.get(p * 3);
             const py = globalPositions.get(p * 3 + 1);
             const pz = globalPositions.get(p * 3 + 2);
@@ -199,7 +199,7 @@ function loadObj(objPath, options) {
         }
 
         // Normals
-        if (defined(n)) {
+        if (defined(n) && (globalNormals.length > 0)) {
             const nx = globalNormals.get(n * 3);
             const ny = globalNormals.get(n * 3 + 1);
             const nz = globalNormals.get(n * 3 + 2);
@@ -209,7 +209,7 @@ function loadObj(objPath, options) {
         }
 
         // UVs
-        if (defined(u)) {
+        if (defined(u) && (globalUvs.length > 0)) {
             const ux = globalUvs.get(u * 2);
             const uy = globalUvs.get(u * 2 + 1);
             primitive.uvs.push(ux);

specs/data/box-missing-attributes/box-missing-attributes.mtl

@@ -0,0 +1,12 @@
+# Blender MTL File: 'box.blend'
+# Material Count: 1
+
+newmtl Material
+Ns 96.078431
+Ka 0.000000 0.000000 0.000000
+Kd 0.640000 0.640000 0.640000
+Ks 0.500000 0.500000 0.500000
+Ke 0.000000 0.000000 0.000000
+Ni 1.000000
+d 1.000000
+illum 2

specs/data/box-missing-attributes/box-missing-attributes.obj

@@ -0,0 +1,20 @@
+# Blender v2.78 (sub 0) OBJ File: 'box.blend'
+# www.blender.org
+mtllib box-missing-attributes.mtl
+o Cube
+v -1.000000 -1.000000 1.000000
+v -1.000000 1.000000 1.000000
+v -1.000000 -1.000000 -1.000000
+v -1.000000 1.000000 -1.000000
+v 1.000000 -1.000000 1.000000
+v 1.000000 1.000000 1.000000
+v 1.000000 -1.000000 -1.000000
+v 1.000000 1.000000 -1.000000
+usemtl Material
+s off
+f 1/1/1 2/2/1 4/3/1 3/4/1
+f 3/5/2 4/6/2 8/7/2 7/8/2
+f 7/9/3 8/10/3 6/11/3 5/12/3
+f 5/13/4 6/14/4 2/15/4 1/16/4
+f 3/5/5 7/17/5 5/18/5 1/16/5
+f 8/19/6 4/6/6 2/15/6 6/20/6

specs/lib/loadObjSpec.js

@@ -40,6 +40,7 @@ const objInvalidContentsPath = 'specs/data/box/box.mtl';
 const objConcavePath = 'specs/data/concave/concave.obj';
 const objUnnormalizedPath = 'specs/data/box-unnormalized/box-unnormalized.obj';
 const objMixedAttributesPath = 'specs/data/box-mixed-attributes/box-mixed-attributes.obj';
+const objMissingAttributesPath = 'specs/data/box-missing-attributes/box-missing-attributes.obj';
 const objInvalidPath = 'invalid.obj';
 
 function getMeshes(data) {
@@ -455,6 +456,14 @@ describe('loadObj', () => {
         expect(primitives[3].indices.length).toBe(6); // 2 faces
     });
 
+    it('does not add missing normals and uvs', async() => {
+        const data = await loadObj(objMissingAttributesPath, options);
+        const primitive = getPrimitives(data)[0];
+        expect(primitive.positions.length).toBeGreaterThan(0);
+        expect(primitive.normals.length).toBe(0);
+        expect(primitive.uvs.length).toBe(0);
+    });
+
     it('throws when file has invalid contents', async () => {
         let thrownError;
         try {