Discard faces that don't have the same attributes

lib/loadObj.js

@@ -112,17 +112,17 @@ function loadObj(objPath, options) {
         mesh.name = getName(name);
         node.meshes.push(mesh);
         addPrimitive();
-
-        // Clear the vertex cache for each new mesh
-        vertexCache = {};
-        vertexCacheCount = 0;
-        vertexCount = 0;
     }
 
     function addPrimitive() {
         primitive = new Primitive();
         primitive.material = activeMaterial;
         mesh.primitives.push(primitive);
+
+        // Clear the vertex cache for each new primitive
+        vertexCache = {};
+        vertexCacheCount = 0;
+        vertexCount = 0;
     }
 
     function useMaterial(name) {
@@ -373,6 +373,17 @@ function loadObj(objPath, options) {
         var isWindingCorrect = true;
         var faceNormal;
 
+        var firstFace = primitive.indices.length === 0;
+        var faceHasUvs = uvs[0].length > 0;
+        var faceHasNormals = normals[0].length > 0;
+        var primitiveHasUvs = primitive.uvs.length > 0;
+        var primitiveHasNormals = primitive.normals.length > 0;
+
+        if (!firstFace && (faceHasUvs !== primitiveHasUvs || faceHasNormals !== primitiveHasNormals)) {
+            // Discard faces that don't use the same attributes
+            return;
+        }
+
         // If normals are defined, find a face normal to use in winding order sanitization.
         // If no face normal, we have to assume the winding is correct.
         if (normals[0].length > 0) {

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

@@ -0,0 +1,12 @@
+# Blender MTL File: 'None'
+# Material Count: 1
+
+newmtl Material
+Ns 96.078431
+Ka 0.100000 0.000000 0.000000
+Kd 0.640000 0.640000 0.640000
+Ks 0.500000 0.500000 0.500000
+Ke 0.000000 0.000000 0.100000
+Ni 1.000000
+d 1.000000
+illum 2

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

@@ -0,0 +1,46 @@
+# Blender v2.78 (sub 0) OBJ File: ''
+# www.blender.org
+mtllib box-mixed-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
+vt 0.0000 0.0000
+vt 1.0000 0.0000
+vt 1.0000 1.0000
+vt 0.0000 1.0000
+vt 0.0000 0.0000
+vt 1.0000 0.0000
+vt 1.0000 1.0000
+vt 0.0000 1.0000
+vt 0.0000 0.0000
+vt 1.0000 0.0000
+vt 1.0000 1.0000
+vt 0.0000 1.0000
+vt 0.0000 0.0000
+vt 1.0000 0.0000
+vt 1.0000 1.0000
+vt 0.0000 1.0000
+vt 1.0000 0.0000
+vt 1.0000 1.0000
+vt 0.0000 0.0000
+vt 0.0000 1.0000
+vn -1.0000 0.0000 0.0000
+vn 0.0000 0.0000 -1.0000
+vn 1.0000 0.0000 0.0000
+vn 0.0000 0.0000 1.0000
+vn 0.0000 -1.0000 0.0000
+vn 0.0000 1.0000 0.0000
+usemtl Material
+s off
+f 1/1/1 2/2/1 4/3/1 3/4/1
+f 3 4 8 7
+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 7//5 5//5 1//5
+f 8/19 4/6 2/15 6/20

specs/lib/loadObjSpec.js

@@ -38,6 +38,7 @@ var objWindowsPaths = 'specs/data/box-windows-paths/box-windows-paths.obj';
 var objInvalidContentsPath = 'specs/data/box/box.mtl';
 var objConcavePath = 'specs/data/concave/concave.obj';
 var objUnnormalizedPath = 'specs/data/box-unnormalized/box-unnormalized.obj';
+var objMixedAttributesPath = 'specs/data/box-mixed-attributes/box-mixed-attributes.obj';
 var objInvalidPath = 'invalid.obj';
 
 function getMeshes(data) {
@@ -486,6 +487,14 @@ describe('loadObj', function() {
             }), done).toResolve();
     });
 
+    it('discards faces that don\'t use the same attributes as other faces in the primitive', function(done) {
+        expect(loadObj(objMixedAttributesPath, options)
+            .then(function(data) {
+                var primitive = getPrimitives(data)[0];
+                expect(primitive.indices.length).toBe(18); // 3 faces removed
+            }), done).toResolve();
+    });
+
     it('throws when file has invalid contents', function(done) {
         expect(loadObj(objInvalidContentsPath, options), done).toRejectWith(RuntimeError);
     });