Add smooting group test .obj with two squares.

Bump version.

README.md

@@ -98,6 +98,7 @@ TinyObjLoader is successfully used in ...
 * PBR material extension for .MTL. Its proposed here: http://exocortex.com/blog/extending_wavefront_mtl_to_support_pbr
 * Callback API for custom loading.
 * Double precision support(for HPC application).
+* Smoothing group
 
 
 ## TODO
@@ -105,8 +106,6 @@ TinyObjLoader is successfully used in ...
 * [ ] Fix obj_sticker example.
 * [ ] More unit test codes.
 * [x] Texture options
-* [ ] Normal vector generation
-  * [ ] Support smoothing groups
 
 ## License
 

examples/obj_sticher/obj_writer.cc

@@ -172,5 +172,3 @@ bool WriteObj(const std::string& filename, const std::vector<tinyobj::shape_t>&
 
   return ret;
 }
-
-

examples/viewer/viewer.cc

@@ -37,11 +37,11 @@ extern "C" {
 #include <windows.h>
 
 #ifdef max
- #undef max
+#undef max
 #endif
 
 #ifdef min
- #undef min
+#undef min
 #endif
 
 #include <mmsystem.h>
@@ -143,15 +143,15 @@ float eye[3], lookat[3], up[3];
 
 GLFWwindow* window;
 
-static std::string GetBaseDir(const std::string &filepath) {
+static std::string GetBaseDir(const std::string& filepath) {
   if (filepath.find_last_of("/\\") != std::string::npos)
     return filepath.substr(0, filepath.find_last_of("/\\"));
   return "";
 }
 
-static bool FileExists(const std::string &abs_filename) {
+static bool FileExists(const std::string& abs_filename) {
   bool ret;
-  FILE *fp = fopen(abs_filename.c_str(), "rb");
+  FILE* fp = fopen(abs_filename.c_str(), "rb");
   if (fp) {
     ret = true;
     fclose(fp);
@@ -191,14 +191,106 @@ static void CalcNormal(float N[3], float v0[3], float v1[3], float v2[3]) {
 
     N[0] /= len;
     N[1] /= len;
+    N[2] /= len;
   }
 }
 
+namespace  // Local utility functions
+{
+struct vec3 {
+  float v[3];
+  vec3() {
+    v[0] = 0.0f;
+    v[1] = 0.0f;
+    v[2] = 0.0f;
+  }
+};
+
+void normalizeVector(vec3 &v) {
+  float len2 = v.v[0] * v.v[0] + v.v[1] * v.v[1] + v.v[2] * v.v[2];
+  if (len2 > 0.0f) {
+    float len = sqrtf(len2);
+
+    v.v[0] /= len;
+    v.v[1] /= len;
+    v.v[2] /= len;
+  }
+}
+
+// Check if `mesh_t` contains smoothing group id.
+bool hasSmoothingGroup(const tinyobj::shape_t& shape)
+{
+  for (size_t i = 0; i < shape.mesh.smoothing_group_ids.size(); i++) {
+    if (shape.mesh.smoothing_group_ids[i] > 0) {
+      return true;
+    }
+  }
+  return false;
+}
+
+void computeSmoothingNormals(const tinyobj::attrib_t& attrib, const tinyobj::shape_t& shape,
+                             std::map<int, vec3>& smoothVertexNormals) {
+  smoothVertexNormals.clear();
+  std::map<int, vec3>::iterator iter;
+
+  for (size_t f = 0; f < shape.mesh.indices.size() / 3; f++) {
+    // Get the three indexes of the face (all faces are triangular)
+    tinyobj::index_t idx0 = shape.mesh.indices[3 * f + 0];
+    tinyobj::index_t idx1 = shape.mesh.indices[3 * f + 1];
+    tinyobj::index_t idx2 = shape.mesh.indices[3 * f + 2];
+
+    // Get the three vertex indexes and coordinates
+    int vi[3];      // indexes
+    float v[3][3];  // coordinates
+
+    for (int k = 0; k < 3; k++) {
+      vi[0] = idx0.vertex_index;
+      vi[1] = idx1.vertex_index;
+      vi[2] = idx2.vertex_index;
+      assert(vi[0] >= 0);
+      assert(vi[1] >= 0);
+      assert(vi[2] >= 0);
+
+      v[0][k] = attrib.vertices[3 * vi[0] + k];
+      v[1][k] = attrib.vertices[3 * vi[1] + k];
+      v[2][k] = attrib.vertices[3 * vi[2] + k];
+    }
+
+    // Compute the normal of the face
+    float normal[3];
+    CalcNormal(normal, v[0], v[1], v[2]);
+
+    // Add the normal to the three vertexes
+    for (size_t i = 0; i < 3; ++i) {
+      iter = smoothVertexNormals.find(vi[i]);
+      if (iter != smoothVertexNormals.end()) {
+        // add
+        iter->second.v[0] += normal[0];
+        iter->second.v[1] += normal[1];
+        iter->second.v[2] += normal[2];
+      } else {
+        smoothVertexNormals[vi[i]].v[0] = normal[0];
+        smoothVertexNormals[vi[i]].v[1] = normal[1];
+        smoothVertexNormals[vi[i]].v[2] = normal[2];
+      }
+    }
+
+  }  // f
+
+  // Normalize the normals, that is, make them unit vectors
+  for (iter = smoothVertexNormals.begin(); iter != smoothVertexNormals.end();
+       iter++) {
+    normalizeVector(iter->second);
+  }
+
+}  // computeSmoothingNormals
+}  // namespace
+
 static bool LoadObjAndConvert(float bmin[3], float bmax[3],
-                       std::vector<DrawObject>* drawObjects,
+                              std::vector<DrawObject>* drawObjects,
-                       std::vector<tinyobj::material_t>& materials,
+                              std::vector<tinyobj::material_t>& materials,
-                       std::map<std::string, GLuint>& textures,
+                              std::map<std::string, GLuint>& textures,
-                       const char* filename) {
+                              const char* filename) {
   tinyobj::attrib_t attrib;
   std::vector<tinyobj::shape_t> shapes;
 
@@ -217,8 +309,8 @@ static bool LoadObjAndConvert(float bmin[3], float bmax[3],
 #endif
 
   std::string err;
-  bool ret =
+  bool ret = tinyobj::LoadObj(&attrib, &shapes, &materials, &err, filename,
-      tinyobj::LoadObj(&attrib, &shapes, &materials, &err, filename, base_dir.c_str());
+                              base_dir.c_str());
   if (!err.empty()) {
     std::cerr << err << std::endl;
   }
@@ -242,56 +334,62 @@ static bool LoadObjAndConvert(float bmin[3], float bmax[3],
   materials.push_back(tinyobj::material_t());
 
   for (size_t i = 0; i < materials.size(); i++) {
-    printf("material[%d].diffuse_texname = %s\n", int(i), materials[i].diffuse_texname.c_str());
+    printf("material[%d].diffuse_texname = %s\n", int(i),
+           materials[i].diffuse_texname.c_str());
   }
 
   // Load diffuse textures
   {
-      for (size_t m = 0; m < materials.size(); m++) {
+    for (size_t m = 0; m < materials.size(); m++) {
-          tinyobj::material_t* mp = &materials[m];
+      tinyobj::material_t* mp = &materials[m];
-          
-          if (mp->diffuse_texname.length() > 0) {
-              // Only load the texture if it is not already loaded
-              if (textures.find(mp->diffuse_texname) == textures.end()) {
-                  GLuint texture_id;
-                  int w, h;
-                  int comp;
 
-                  std::string texture_filename = mp->diffuse_texname;
+      if (mp->diffuse_texname.length() > 0) {
-                  if (!FileExists(texture_filename)) {
+        // Only load the texture if it is not already loaded
-                    // Append base dir.
+        if (textures.find(mp->diffuse_texname) == textures.end()) {
-                    texture_filename = base_dir + mp->diffuse_texname;
+          GLuint texture_id;
-                    if (!FileExists(texture_filename)) {
+          int w, h;
-                      std::cerr << "Unable to find file: " << mp->diffuse_texname << std::endl;
+          int comp;
-                      exit(1);
-                    }
-                  }
-                  
-                  unsigned char* image = stbi_load(texture_filename.c_str(), &w, &h, &comp, STBI_default);
-                  if (!image) {
-                      std::cerr << "Unable to load texture: " << texture_filename << std::endl;
-                      exit(1);
-                  }
-                  std::cout << "Loaded texture: " << texture_filename << ", w = " << w << ", h = " << h << ", comp = " << comp << std::endl;
 
-                  glGenTextures(1, &texture_id);
+          std::string texture_filename = mp->diffuse_texname;
-                  glBindTexture(GL_TEXTURE_2D, texture_id);
+          if (!FileExists(texture_filename)) {
-                  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+            // Append base dir.
-                  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+            texture_filename = base_dir + mp->diffuse_texname;
-                  if (comp == 3) {
+            if (!FileExists(texture_filename)) {
-                      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, w, h, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
+              std::cerr << "Unable to find file: " << mp->diffuse_texname
-                  }
+                        << std::endl;
-                  else if (comp == 4) {
+              exit(1);
-                      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);
+            }
-                  } else {
-                      assert(0); // TODO
-                  }
-                  glBindTexture(GL_TEXTURE_2D, 0);
-                  stbi_image_free(image);
-                  textures.insert(std::make_pair(mp->diffuse_texname, texture_id));
-              }
           }
+
+          unsigned char* image =
+              stbi_load(texture_filename.c_str(), &w, &h, &comp, STBI_default);
+          if (!image) {
+            std::cerr << "Unable to load texture: " << texture_filename
+                      << std::endl;
+            exit(1);
+          }
+          std::cout << "Loaded texture: " << texture_filename << ", w = " << w
+                    << ", h = " << h << ", comp = " << comp << std::endl;
+
+          glGenTextures(1, &texture_id);
+          glBindTexture(GL_TEXTURE_2D, texture_id);
+          glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+          glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+          if (comp == 3) {
+            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, w, h, 0, GL_RGB,
+                         GL_UNSIGNED_BYTE, image);
+          } else if (comp == 4) {
+            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA,
+                         GL_UNSIGNED_BYTE, image);
+          } else {
+            assert(0);  // TODO
+          }
+          glBindTexture(GL_TEXTURE_2D, 0);
+          stbi_image_free(image);
+          textures.insert(std::make_pair(mp->diffuse_texname, texture_id));
+        }
       }
+    }
   }
 
   bmin[0] = bmin[1] = bmin[2] = std::numeric_limits<float>::max();
@@ -301,30 +399,55 @@ static bool LoadObjAndConvert(float bmin[3], float bmax[3],
     for (size_t s = 0; s < shapes.size(); s++) {
       DrawObject o;
       std::vector<float> buffer;  // pos(3float), normal(3float), color(3float)
+
+      // Check for smoothing group and compute smoothing normals
+      std::map<int, vec3> smoothVertexNormals;
+      if (hasSmoothingGroup(shapes[s]) > 0) {
+        std::cout << "Compute smoothingNormal for shape [" << s << "]" << std::endl;
+        computeSmoothingNormals(attrib, shapes[s], smoothVertexNormals);
+      }
+
       for (size_t f = 0; f < shapes[s].mesh.indices.size() / 3; f++) {
         tinyobj::index_t idx0 = shapes[s].mesh.indices[3 * f + 0];
         tinyobj::index_t idx1 = shapes[s].mesh.indices[3 * f + 1];
         tinyobj::index_t idx2 = shapes[s].mesh.indices[3 * f + 2];
-        
+
         int current_material_id = shapes[s].mesh.material_ids[f];
 
-        if ((current_material_id < 0) || (current_material_id >= static_cast<int>(materials.size()))) {
+        if ((current_material_id < 0) ||
+            (current_material_id >= static_cast<int>(materials.size()))) {
           // Invaid material ID. Use default material.
-          current_material_id = materials.size() - 1; // Default material is added to the last item in `materials`.
+          current_material_id =
+              materials.size() -
+              1;  // Default material is added to the last item in `materials`.
         }
-        //if (current_material_id >= materials.size()) {
+        // if (current_material_id >= materials.size()) {
-        //    std::cerr << "Invalid material index: " << current_material_id << std::endl;
+        //    std::cerr << "Invalid material index: " << current_material_id <<
+        //    std::endl;
         //}
         //
         float diffuse[3];
         for (size_t i = 0; i < 3; i++) {
-            diffuse[i] = materials[current_material_id].diffuse[i];
+          diffuse[i] = materials[current_material_id].diffuse[i];
         }
         float tc[3][2];
         if (attrib.texcoords.size() > 0) {
-            assert(attrib.texcoords.size() > 2 * idx0.texcoord_index + 1);
+          if ((idx0.texcoord_index < 0) || (idx1.texcoord_index < 0) ||
-            assert(attrib.texcoords.size() > 2 * idx1.texcoord_index + 1);
+              (idx2.texcoord_index < 0)) {
-            assert(attrib.texcoords.size() > 2 * idx2.texcoord_index + 1);
+            // face does not contain valid uv index.
+            tc[0][0] = 0.0f;
+            tc[0][1] = 0.0f;
+            tc[1][0] = 0.0f;
+            tc[1][1] = 0.0f;
+            tc[2][0] = 0.0f;
+            tc[2][1] = 0.0f;
+          } else {
+            assert(attrib.texcoords.size() >
+                   size_t(2 * idx0.texcoord_index + 1));
+            assert(attrib.texcoords.size() >
+                   size_t(2 * idx1.texcoord_index + 1));
+            assert(attrib.texcoords.size() >
+                   size_t(2 * idx2.texcoord_index + 1));
 
             // Flip Y coord.
             tc[0][0] = attrib.texcoords[2 * idx0.texcoord_index];
@@ -333,13 +456,14 @@ static bool LoadObjAndConvert(float bmin[3], float bmax[3],
             tc[1][1] = 1.0f - attrib.texcoords[2 * idx1.texcoord_index + 1];
             tc[2][0] = attrib.texcoords[2 * idx2.texcoord_index];
             tc[2][1] = 1.0f - attrib.texcoords[2 * idx2.texcoord_index + 1];
+          }
         } else {
-            tc[0][0] = 0.0f;
+          tc[0][0] = 0.0f;
-            tc[0][1] = 0.0f;
+          tc[0][1] = 0.0f;
-            tc[1][0] = 0.0f;
+          tc[1][0] = 0.0f;
-            tc[1][1] = 0.0f;
+          tc[1][1] = 0.0f;
-            tc[2][0] = 0.0f;
+          tc[2][0] = 0.0f;
-            tc[2][1] = 0.0f;
+          tc[2][1] = 0.0f;
         }
 
         float v[3][3];
@@ -363,27 +487,63 @@ static bool LoadObjAndConvert(float bmin[3], float bmax[3],
         }
 
         float n[3][3];
-        if (attrib.normals.size() > 0) {
+        {
-          int f0 = idx0.normal_index;
+          bool invalid_normal_index = false;
-          int f1 = idx1.normal_index;
+          if (attrib.normals.size() > 0) {
-          int f2 = idx2.normal_index;
+            int nf0 = idx0.normal_index;
-          assert(f0 >= 0);
+            int nf1 = idx1.normal_index;
-          assert(f1 >= 0);
+            int nf2 = idx2.normal_index;
-          assert(f2 >= 0);
+
-          for (int k = 0; k < 3; k++) {
+            if ((nf0 < 0) || (nf1 < 0) || (nf2 < 0)) {
-            n[0][k] = attrib.normals[3 * f0 + k];
+              // normal index is missing from this face.
-            n[1][k] = attrib.normals[3 * f1 + k];
+              invalid_normal_index = true;
-            n[2][k] = attrib.normals[3 * f2 + k];
+            } else {
+              for (int k = 0; k < 3; k++) {
+                assert(size_t(3 * nf0 + k) < attrib.normals.size());
+                assert(size_t(3 * nf1 + k) < attrib.normals.size());
+                assert(size_t(3 * nf2 + k) < attrib.normals.size());
+                n[0][k] = attrib.normals[3 * nf0 + k];
+                n[1][k] = attrib.normals[3 * nf1 + k];
+                n[2][k] = attrib.normals[3 * nf2 + k];
+              }
+            }
+          } else {
+            invalid_normal_index = true;
+          }
+
+          if (invalid_normal_index && !smoothVertexNormals.empty()) {
+            // Use smoothing normals
+            int f0 = idx0.vertex_index;
+            int f1 = idx1.vertex_index;
+            int f2 = idx2.vertex_index;
+
+            if (f0 >= 0 && f1 >= 0 && f2 >= 0) {
+              n[0][0] = smoothVertexNormals[f0].v[0];
+              n[0][1] = smoothVertexNormals[f0].v[1];
+              n[0][2] = smoothVertexNormals[f0].v[2];
+
+              n[1][0] = smoothVertexNormals[f1].v[0];
+              n[1][1] = smoothVertexNormals[f1].v[1];
+              n[1][2] = smoothVertexNormals[f1].v[2];
+
+              n[2][0] = smoothVertexNormals[f2].v[0];
+              n[2][1] = smoothVertexNormals[f2].v[1];
+              n[2][2] = smoothVertexNormals[f2].v[2];
+
+              invalid_normal_index = false;
+            }
+          }
+
+          if (invalid_normal_index) {
+            // compute geometric normal
+            CalcNormal(n[0], v[0], v[1], v[2]);
+            n[1][0] = n[0][0];
+            n[1][1] = n[0][1];
+            n[1][2] = n[0][2];
+            n[2][0] = n[0][0];
+            n[2][1] = n[0][1];
+            n[2][2] = n[0][2];
           }
-        } else {
-          // compute geometric normal
-          CalcNormal(n[0], v[0], v[1], v[2]);
-          n[1][0] = n[0][0];
-          n[1][1] = n[0][1];
-          n[1][2] = n[0][2];
-          n[2][0] = n[0][0];
-          n[2][1] = n[0][1];
-          n[2][2] = n[0][2];
         }
 
         for (int k = 0; k < 3; k++) {
@@ -396,11 +556,9 @@ static bool LoadObjAndConvert(float bmin[3], float bmax[3],
           // Combine normal and diffuse to get color.
           float normal_factor = 0.2;
           float diffuse_factor = 1 - normal_factor;
-          float c[3] = {
+          float c[3] = {n[k][0] * normal_factor + diffuse[0] * diffuse_factor,
-              n[k][0] * normal_factor + diffuse[0] * diffuse_factor,
+                        n[k][1] * normal_factor + diffuse[1] * diffuse_factor,
-              n[k][1] * normal_factor + diffuse[1] * diffuse_factor,
+                        n[k][2] * normal_factor + diffuse[2] * diffuse_factor};
-              n[k][2] * normal_factor + diffuse[2] * diffuse_factor
-          };
           float len2 = c[0] * c[0] + c[1] * c[1] + c[2] * c[2];
           if (len2 > 0.0f) {
             float len = sqrtf(len2);
@@ -412,7 +570,7 @@ static bool LoadObjAndConvert(float bmin[3], float bmax[3],
           buffer.push_back(c[0] * 0.5 + 0.5);
           buffer.push_back(c[1] * 0.5 + 0.5);
           buffer.push_back(c[2] * 0.5 + 0.5);
-          
+
           buffer.push_back(tc[k][0]);
           buffer.push_back(tc[k][1]);
         }
@@ -422,19 +580,22 @@ static bool LoadObjAndConvert(float bmin[3], float bmax[3],
       o.numTriangles = 0;
 
       // OpenGL viewer does not support texturing with per-face material.
-      if (shapes[s].mesh.material_ids.size() > 0 && shapes[s].mesh.material_ids.size() > s) {
+      if (shapes[s].mesh.material_ids.size() > 0 &&
-          o.material_id = shapes[s].mesh.material_ids[0]; // use the material ID of the first face.
+          shapes[s].mesh.material_ids.size() > s) {
+        o.material_id = shapes[s].mesh.material_ids[0];  // use the material ID
+                                                         // of the first face.
       } else {
-          o.material_id = materials.size() - 1; // = ID for default material.
+        o.material_id = materials.size() - 1;  // = ID for default material.
       }
       printf("shape[%d] material_id %d\n", int(s), int(o.material_id));
-          
+
       if (buffer.size() > 0) {
         glGenBuffers(1, &o.vb_id);
         glBindBuffer(GL_ARRAY_BUFFER, o.vb_id);
-        glBufferData(GL_ARRAY_BUFFER, buffer.size() * sizeof(float), &buffer.at(0),
+        glBufferData(GL_ARRAY_BUFFER, buffer.size() * sizeof(float),
-                     GL_STATIC_DRAW);
+                     &buffer.at(0), GL_STATIC_DRAW);
-        o.numTriangles = buffer.size() / (3 + 3 + 3 + 2) / 3; // 3:vtx, 3:normal, 3:col, 2:texcoord
+        o.numTriangles = buffer.size() / (3 + 3 + 3 + 2) /
+                         3;  // 3:vtx, 3:normal, 3:col, 2:texcoord
 
         printf("shape[%d] # of triangles = %d\n", static_cast<int>(s),
                o.numTriangles);
@@ -467,7 +628,7 @@ static void reshapeFunc(GLFWwindow* window, int w, int h) {
 }
 
 static void keyboardFunc(GLFWwindow* window, int key, int scancode, int action,
-                  int mods) {
+                         int mods) {
   (void)window;
   (void)scancode;
   (void)mods;
@@ -549,7 +710,9 @@ static void motionFunc(GLFWwindow* window, double mouse_x, double mouse_y) {
   prevMouseY = mouse_y;
 }
 
-static void Draw(const std::vector<DrawObject>& drawObjects, std::vector<tinyobj::material_t>& materials, std::map<std::string, GLuint>& textures) {
+static void Draw(const std::vector<DrawObject>& drawObjects,
+                 std::vector<tinyobj::material_t>& materials,
+                 std::map<std::string, GLuint>& textures) {
   glPolygonMode(GL_FRONT, GL_FILL);
   glPolygonMode(GL_BACK, GL_FILL);
 
@@ -572,7 +735,7 @@ static void Draw(const std::vector<DrawObject>& drawObjects, std::vector<tinyobj
     if ((o.material_id < materials.size())) {
       std::string diffuse_texname = materials[o.material_id].diffuse_texname;
       if (textures.find(diffuse_texname) != textures.end()) {
-          glBindTexture(GL_TEXTURE_2D, textures[diffuse_texname]);
+        glBindTexture(GL_TEXTURE_2D, textures[diffuse_texname]);
       }
     }
     glVertexPointer(3, GL_FLOAT, stride, (const void*)0);
@@ -668,7 +831,8 @@ int main(int argc, char** argv) {
   float bmin[3], bmax[3];
   std::vector<tinyobj::material_t> materials;
   std::map<std::string, GLuint> textures;
-  if (false == LoadObjAndConvert(bmin, bmax, &gDrawObjects, materials, textures, argv[1])) {
+  if (false == LoadObjAndConvert(bmin, bmax, &gDrawObjects, materials, textures,
+                                 argv[1])) {
     return -1;
   }
 

experimental/tinyobj_loader_opt.h

@@ -1440,7 +1440,9 @@ bool parseObj(attrib_t *attrib, std::vector<shape_t> *shapes,
     // std::cout << "mtllib :" << material_filename << std::endl;
 
     auto t1 = std::chrono::high_resolution_clock::now();
-
+	if (material_filename.back() == '\r') {
+			material_filename.pop_back();
+	}
     std::ifstream ifs(material_filename);
     if (ifs.good()) {
       LoadMtl(&material_map, materials, &ifs);
@@ -1516,13 +1518,13 @@ bool parseObj(attrib_t *attrib, std::vector<shape_t> *shapes,
     StackVector<std::thread, 16> workers;
 
     for (size_t t = 0; t < num_threads; t++) {
-      int material_id = -1;  // -1 = default unknown material.
       workers->push_back(std::thread([&, t]() {
         size_t v_count = v_offsets[t];
         size_t n_count = n_offsets[t];
         size_t t_count = t_offsets[t];
         size_t f_count = f_offsets[t];
         size_t face_count = face_offsets[t];
+		int material_id = -1;  // -1 = default unknown material.
 
         for (size_t i = 0; i < commands[t].size(); i++) {
           if (commands[t][i].type == COMMAND_EMPTY) {
@@ -1579,7 +1581,19 @@ bool parseObj(attrib_t *attrib, std::vector<shape_t> *shapes,
     for (size_t t = 0; t < workers->size(); t++) {
       workers[t].join();
     }
-
+	if(material_map.size()>1&& num_threads>1) {
+			for (size_t t = 0; t < num_threads; t++) {
+				size_t face_count = face_offsets[t];
+				if (-1 == attrib->material_ids[face_count]) {
+					int prev_material_id = attrib->material_ids[face_count - 1];
+					size_t max_face_offset = (t == num_threads - 1) ? attrib->material_ids.size() : face_offsets[t + 1];
+					for (int i = face_count; i<max_face_offset; ++i) {
+						if (attrib->material_ids[i] != -1) break;
+						attrib->material_ids[i] = prev_material_id;
+					}
+				}
+			}
+	}
     auto t_end = std::chrono::high_resolution_clock::now();
     ms_merge = t_end - t_start;
   }

loader_example.cc

@@ -29,6 +29,13 @@ extern "C" {
 #endif
 #endif
 
+#ifdef __clang__
+#pragma clang diagnostic push
+#if __has_warning("-Wzero-as-null-pointer-constant")
+#pragma clang diagnostic ignored "-Wzero-as-null-pointer-constant"
+#endif
+#endif
+
 class timerutil {
  public:
 #ifdef _WIN32

models/issue-161-inconsistent-f.obj

@@ -0,0 +1,37 @@
+o cube
+mtllib cube.mtl
+
+v -0.500000 -0.500000 0.500000
+v 0.500000 -0.500000 0.500000
+v -0.500000 0.500000 0.500000
+v 0.500000 0.500000 0.500000
+v -0.500000 0.500000 -0.500000
+v 0.500000 0.500000 -0.500000
+v -0.500000 -0.500000 -0.500000
+v 0.500000 -0.500000 -0.500000
+
+vt 0.000000 0.000000
+vt 1.000000 0.000000
+vt 0.000000 1.000000
+vt 1.000000 1.000000
+
+g cube
+usemtl cube
+s 1
+f 1/1 2/2 3/3
+f 3/3 2/2 4/4
+s 2
+f 3/1 4/2 5/3
+f 5/3 4/2 6/4
+s 3
+f 5/4 6/3 7/2
+f 7/2 6/3 8/1
+s 4
+f 7/1 8/2 1/3
+f 1/3 8/2 2/4
+s 5
+f 2/1 8/2 4/3
+f 4/3 8/2 6/4
+s 6
+f 7/1 1/2 5/3
+f 5 1 3

models/issue-162-smoothing-group.mtl

@@ -0,0 +1,23 @@
+newmtl test1
+  Ns 10.0000
+  Ni 1.5000
+  d 1.0000
+  Tr 0.0000
+  Tf 1.0000 1.0000 1.0000 
+  illum 2
+  Ka 0.0000 0.0000 0.0000
+  Kd 0.5 0.2 0.2
+  Ks 0.0000 0.0000 0.0000
+  Ke 0.0000 0.0000 0.0000
+
+ newmtl test2
+  Ns 10.0000
+  Ni 1.5000
+  d 1.0000
+  Tr 0.0000
+  Tf 1.0000 1.0000 1.0000 
+  illum 2
+  Ka 0.0000 0.0000 0.0000
+  Kd 0.2 0.5 0.2
+  Ks 0.0000 0.0000 0.0000
+  Ke 0.0000 0.0000 0.0000

models/issue-162-smoothing-group.obj

@@ -0,0 +1,51 @@
+
+# cube.obj
+#
+
+mtllib issue-162-smoothing-group.mtl
+
+v -0.500000 -0.500000 0.500000
+v 0.500000 -0.500000 0.500000
+v -0.500000 0.500000 0.500000
+v 0.500000 0.500000 0.500000
+v -0.500000 0.500000 -0.500000
+v 0.500000 0.500000 -0.500000
+v -0.500000 -0.500000 -0.500000
+v 0.500000 -0.500000 -0.500000
+
+vt 0.000000 0.000000
+vt 1.000000 0.000000
+vt 0.000000 1.000000
+vt 1.000000 1.000000
+
+vn 0.000000 0.000000 1.000000
+vn 0.000000 1.000000 0.000000
+vn 0.000000 0.000000 -1.000000
+vn 0.000000 -1.000000 0.000000
+vn 1.000000 0.000000 0.000000
+vn -1.000000 0.000000 0.000000
+
+usemtl test1
+g test1
+s 1
+f 1/1/1 2/2/1 3/3/1
+f 3/3/1 2/2/1 4/4/1
+
+usemtl test2
+g test2
+
+s off
+f 3/1/2 4/2/2 5/3/2
+f 5/3/2 4/2/2 6/4/2
+s 3
+f 5/4/3 6/3/3 7/2/3
+f 7/2/3 6/3/3 8/1/3
+s 4
+f 7/1/4 8/2/4 1/3/4
+f 1/3/4 8/2/4 2/4/4
+s 0
+f 2/1/5 8/2/5 4/3/5
+f 4/3/5 8/2/5 6/4/5
+s 6
+f 7/1/6 1/2/6 5/3/6
+f 5/3/6 1/2/6 3/4/6

models/smoothing-group-two-squares.obj

@@ -0,0 +1,22 @@
+# from tinyobjloader issue #29
+
+v 0.000000 2.000000 0.000000
+v 0.000000 0.000000 0.000000
+v 2.000000 0.000000 0.000000
+v 2.000000 2.000000 0.000000
+v 4.000000 0.000000 -3.255298
+v 4.000000 2.000000 -3.255298
+#vn 0.000000 0.000000 1.000000
+#vn 0.000000 0.000000 1.000000
+#vn 0.276597 0.000000 0.960986
+#vn 0.276597 0.000000 0.960986
+#vn 0.531611 0.000000 0.846988
+#vn 0.531611 0.000000 0.846988
+# 6 vertices
+
+# 6 normals
+
+g all
+s 1
+f 1//1 2//2 3//3 4//4
+f 4//4 3//3 5//5

models/smoothing-normal.mtl

@@ -0,0 +1,24 @@
+newmtl white
+Ka 0 0 0
+Kd 1 1 1
+Ks 0 0 0
+
+newmtl red
+Ka 0 0 0
+Kd 1 0 0
+Ks 0 0 0
+
+newmtl green
+Ka 0 0 0
+Kd 0 1 0
+Ks 0 0 0
+
+newmtl blue
+Ka 0 0 0
+Kd 0 0 1
+Ks 0 0 0
+
+newmtl light
+Ka 20 20 20
+Kd 1 1 1
+Ks 0 0 0

models/smoothing-normal.obj

@@ -0,0 +1,35 @@
+mtllib smoothing-normal.mtl
+
+v 0.000000 2.000000 2.000000
+v 0.000000 0.000000 2.000000
+v 2.000000 0.000000 2.000000
+v 2.000000 2.000000 2.000000
+v 0.000000 2.000000 0.000000
+v 0.000000 0.000000 0.000000
+v 2.000000 0.000000 0.000000
+v 2.000000 2.000000 0.000000
+# 8 vertices
+
+g front cube
+usemtl white
+s 1
+f 1 2 3 4
+#g bottom cube
+#usemtl white
+s 1
+f 2 6 7 3
+
+g back cube
+# expects white material
+s off
+f 8 7 6 5
+#g right cube
+#usemtl red
+#f 4 3 7 8
+#g top cube
+#usemtl white
+#f 5 1 4 8
+#g left cube
+#usemtl green
+#f 5 6 2 1
+# 6 elements

tests/tester.cc

@@ -717,6 +717,40 @@ TEST_CASE("texture-name-whitespace", "[Issue145]") {
 
 }
 
+TEST_CASE("smoothing-group", "[Issue162]") {
+  tinyobj::attrib_t attrib;
+  std::vector<tinyobj::shape_t> shapes;
+  std::vector<tinyobj::material_t> materials;
+
+  std::string err;
+  bool ret = tinyobj::LoadObj(&attrib, &shapes, &materials, &err, "../models/issue-162-smoothing-group.obj", gMtlBasePath);
+
+  
+  if (!err.empty()) {
+    std::cerr << "[Issue162] " << err << std::endl;
+  }
+
+  REQUIRE(true == ret);
+  REQUIRE(2 == shapes.size());
+
+  REQUIRE(2 == shapes[0].mesh.smoothing_group_ids.size());
+  REQUIRE(1 == shapes[0].mesh.smoothing_group_ids[0]);
+  REQUIRE(1 == shapes[0].mesh.smoothing_group_ids[1]);
+
+  REQUIRE(10 == shapes[1].mesh.smoothing_group_ids.size());
+  REQUIRE(0 == shapes[1].mesh.smoothing_group_ids[0]);
+  REQUIRE(0 == shapes[1].mesh.smoothing_group_ids[1]);
+  REQUIRE(3 == shapes[1].mesh.smoothing_group_ids[2]);
+  REQUIRE(3 == shapes[1].mesh.smoothing_group_ids[3]);
+  REQUIRE(4 == shapes[1].mesh.smoothing_group_ids[4]);
+  REQUIRE(4 == shapes[1].mesh.smoothing_group_ids[5]);
+  REQUIRE(0 == shapes[1].mesh.smoothing_group_ids[6]);
+  REQUIRE(0 == shapes[1].mesh.smoothing_group_ids[7]);
+  REQUIRE(6 == shapes[1].mesh.smoothing_group_ids[8]);
+  REQUIRE(6 == shapes[1].mesh.smoothing_group_ids[9]);
+
+}
+
 #if 0
 int
 main(

tiny_obj_loader.h

@@ -1,7 +1,7 @@
 /*
 The MIT License (MIT)
 
-Copyright (c) 2012-2017 Syoyo Fujita and many contributors.
+Copyright (c) 2012-2018 Syoyo Fujita and many contributors.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -23,6 +23,7 @@ THE SOFTWARE.
 */
 
 //
+// version 1.1.1 : Support smoothing groups(#162)
 // version 1.1.0 : Support parsing vertex color(#144)
 // version 1.0.8 : Fix parsing `g` tag just after `usemtl`(#138)
 // version 1.0.7 : Support multiple tex options(#126)
@@ -51,6 +52,13 @@ THE SOFTWARE.
 
 namespace tinyobj {
 
+#ifdef __clang__
+#pragma clang diagnostic push
+#if __has_warning("-Wzero-as-null-pointer-constant")
+#pragma clang diagnostic ignored "-Wzero-as-null-pointer-constant"
+#endif
+#endif
+
 // https://en.wikipedia.org/wiki/Wavefront_.obj_file says ...
 //
 //  -blendu on | off                       # set horizontal texture blending
@@ -218,7 +226,10 @@ typedef struct {
                                                  // face. 3 = polygon, 4 = quad,
                                                  // ... Up to 255.
   std::vector<int> material_ids;                 // per-face material ID
-  std::vector<tag_t> tags;                       // SubD tag
+  std::vector<unsigned int> smoothing_group_ids;  // per-face smoothing group
+                                                  // ID(0 = off. positive value
+                                                  // = group id)
+  std::vector<tag_t> tags;                        // SubD tag
 } mesh_t;
 
 typedef struct {
@@ -366,14 +377,25 @@ namespace tinyobj {
 
 MaterialReader::~MaterialReader() {}
 
-struct vertex_index {
+struct vertex_index_t {
   int v_idx, vt_idx, vn_idx;
-  vertex_index() : v_idx(-1), vt_idx(-1), vn_idx(-1) {}
+  vertex_index_t() : v_idx(-1), vt_idx(-1), vn_idx(-1) {}
-  explicit vertex_index(int idx) : v_idx(idx), vt_idx(idx), vn_idx(idx) {}
+  explicit vertex_index_t(int idx) : v_idx(idx), vt_idx(idx), vn_idx(idx) {}
-  vertex_index(int vidx, int vtidx, int vnidx)
+  vertex_index_t(int vidx, int vtidx, int vnidx)
       : v_idx(vidx), vt_idx(vtidx), vn_idx(vnidx) {}
 };
 
+// Internal data structure for face representation
+// index + smoothing group.
+struct face_t {
+  unsigned int
+      smoothing_group_id;  // smoothing group id. 0 = smoothing groupd is off.
+  int pad_;
+  std::vector<vertex_index_t> vertex_indices;  // face vertex indices.
+
+  face_t() : smoothing_group_id(0) {}
+};
+
 struct tag_sizes {
   tag_sizes() : num_ints(0), num_reals(0), num_strings(0) {}
   int num_ints;
@@ -661,11 +683,12 @@ static inline void parseV(real_t *x, real_t *y, real_t *z, real_t *w,
 }
 
 // Extension: parse vertex with colors(6 items)
-static inline bool parseVertexWithColor(real_t *x, real_t *y, real_t *z, real_t *r,
+static inline bool parseVertexWithColor(real_t *x, real_t *y, real_t *z,
-                          real_t *g, real_t *b,
+                                        real_t *r, real_t *g, real_t *b,
-                          const char **token, const double default_x = 0.0,
+                                        const char **token,
-                          const double default_y = 0.0,
+                                        const double default_x = 0.0,
-                          const double default_z = 0.0) {
+                                        const double default_y = 0.0,
+                                        const double default_z = 0.0) {
   (*x) = parseReal(token, default_x);
   (*y) = parseReal(token, default_y);
   (*z) = parseReal(token, default_z);
@@ -728,7 +751,7 @@ static tag_sizes parseTagTriple(const char **token) {
     return ts;
   }
 
-  (*token)++; // Skip '/'
+  (*token)++;  // Skip '/'
 
   (*token) += strspn((*token), " \t");
   ts.num_reals = atoi((*token));
@@ -736,7 +759,7 @@ static tag_sizes parseTagTriple(const char **token) {
   if ((*token)[0] != '/') {
     return ts;
   }
-  (*token)++; // Skip '/'
+  (*token)++;  // Skip '/'
 
   ts.num_strings = parseInt(token);
 
@@ -745,12 +768,12 @@ static tag_sizes parseTagTriple(const char **token) {
 
 // Parse triples with index offsets: i, i/j/k, i//k, i/j
 static bool parseTriple(const char **token, int vsize, int vnsize, int vtsize,
-                        vertex_index *ret) {
+                        vertex_index_t *ret) {
   if (!ret) {
     return false;
   }
 
-  vertex_index vi(-1);
+  vertex_index_t vi(-1);
 
   if (!fixIndex(atoi((*token)), vsize, &(vi.v_idx))) {
     return false;
@@ -798,8 +821,8 @@ static bool parseTriple(const char **token, int vsize, int vnsize, int vtsize,
 }
 
 // Parse raw triples: i, i/j/k, i//k, i/j
-static vertex_index parseRawTriple(const char **token) {
+static vertex_index_t parseRawTriple(const char **token) {
-  vertex_index vi(static_cast<int>(0));  // 0 is an invalid index in OBJ
+  vertex_index_t vi(static_cast<int>(0));  // 0 is an invalid index in OBJ
 
   vi.v_idx = atoi((*token));
   (*token) += strcspn((*token), "/ \t\r");
@@ -907,7 +930,7 @@ static bool ParseTextureNameAndOption(std::string *texname,
       token += 4;
       parseReal2(&(texopt->brightness), &(texopt->contrast), &token, 0.0, 1.0);
     } else {
-      // Assume texture filename
+    // Assume texture filename
 #if 0
       size_t len = strcspn(token, " \t\r");  // untile next space
       texture_name = std::string(token, token + len);
@@ -971,60 +994,215 @@ static void InitMaterial(material_t *material) {
   material->unknown_parameter.clear();
 }
 
-static bool exportFaceGroupToShape(
+// code from https://wrf.ecse.rpi.edu//Research/Short_Notes/pnpoly.html
-    shape_t *shape, const std::vector<std::vector<vertex_index> > &faceGroup,
+static int pnpoly(int nvert, float *vertx, float *verty, float testx,
-    const std::vector<tag_t> &tags, const int material_id,
+                  float testy) {
-    const std::string &name, bool triangulate) {
+  int i, j, c = 0;
+  for (i = 0, j = nvert - 1; i < nvert; j = i++) {
+    if (((verty[i] > testy) != (verty[j] > testy)) &&
+        (testx <
+         (vertx[j] - vertx[i]) * (testy - verty[i]) / (verty[j] - verty[i]) +
+             vertx[i]))
+      c = !c;
+  }
+  return c;
+}
+
+// TODO(syoyo): refactor function.
+static bool exportFaceGroupToShape(shape_t *shape,
+                                   const std::vector<face_t> &faceGroup,
+                                   const std::vector<tag_t> &tags,
+                                   const int material_id,
+                                   const std::string &name, bool triangulate,
+                                   const std::vector<real_t> &v) {
   if (faceGroup.empty()) {
     return false;
   }
 
   // Flatten vertices and indices
   for (size_t i = 0; i < faceGroup.size(); i++) {
-    const std::vector<vertex_index> &face = faceGroup[i];
+    const face_t &face = faceGroup[i];
 
-    vertex_index i0 = face[0];
+    vertex_index_t i0 = face.vertex_indices[0];
-    vertex_index i1(-1);
+    vertex_index_t i1(-1);
-    vertex_index i2 = face[1];
+    vertex_index_t i2 = face.vertex_indices[1];
 
-    size_t npolys = face.size();
+    size_t npolys = face.vertex_indices.size();
 
     if (triangulate) {
-      // Polygon -> triangle fan conversion
+      // find the two axes to work in
-      for (size_t k = 2; k < npolys; k++) {
+      size_t axes[2] = {1, 2};
-        i1 = i2;
+      for (size_t k = 0; k < npolys; ++k) {
-        i2 = face[k];
+        i0 = face.vertex_indices[(k + 0) % npolys];
+        i1 = face.vertex_indices[(k + 1) % npolys];
+        i2 = face.vertex_indices[(k + 2) % npolys];
+        size_t vi0 = size_t(i0.v_idx);
+        size_t vi1 = size_t(i1.v_idx);
+        size_t vi2 = size_t(i2.v_idx);
+        real_t v0x = v[vi0 * 3 + 0];
+        real_t v0y = v[vi0 * 3 + 1];
+        real_t v0z = v[vi0 * 3 + 2];
+        real_t v1x = v[vi1 * 3 + 0];
+        real_t v1y = v[vi1 * 3 + 1];
+        real_t v1z = v[vi1 * 3 + 2];
+        real_t v2x = v[vi2 * 3 + 0];
+        real_t v2y = v[vi2 * 3 + 1];
+        real_t v2z = v[vi2 * 3 + 2];
+        real_t e0x = v1x - v0x;
+        real_t e0y = v1y - v0y;
+        real_t e0z = v1z - v0z;
+        real_t e1x = v2x - v1x;
+        real_t e1y = v2y - v1y;
+        real_t e1z = v2z - v1z;
+        float cx = std::fabs(e0y * e1z - e0z * e1y);
+        float cy = std::fabs(e0z * e1x - e0x * e1z);
+        float cz = std::fabs(e0x * e1y - e0y * e1x);
+        const float epsilon = 0.0001f;
+        if (cx > epsilon || cy > epsilon || cz > epsilon) {
+          // found a corner
+          if (cx > cy && cx > cz) {
+          } else {
+            axes[0] = 0;
+            if (cz > cx && cz > cy) axes[1] = 1;
+          }
+          break;
+        }
+      }
 
-        index_t idx0, idx1, idx2;
+      real_t area = 0;
-        idx0.vertex_index = i0.v_idx;
+      for (size_t k = 0; k < npolys; ++k) {
-        idx0.normal_index = i0.vn_idx;
+        i0 = face.vertex_indices[(k + 0) % npolys];
-        idx0.texcoord_index = i0.vt_idx;
+        i1 = face.vertex_indices[(k + 1) % npolys];
-        idx1.vertex_index = i1.v_idx;
+        size_t vi0 = size_t(i0.v_idx);
-        idx1.normal_index = i1.vn_idx;
+        size_t vi1 = size_t(i1.v_idx);
-        idx1.texcoord_index = i1.vt_idx;
+        real_t v0x = v[vi0 * 3 + axes[0]];
-        idx2.vertex_index = i2.v_idx;
+        real_t v0y = v[vi0 * 3 + axes[1]];
-        idx2.normal_index = i2.vn_idx;
+        real_t v1x = v[vi1 * 3 + axes[0]];
-        idx2.texcoord_index = i2.vt_idx;
+        real_t v1y = v[vi1 * 3 + axes[1]];
+        area += (v0x * v1y - v0y * v1x) * 0.5f;
+      }
 
-        shape->mesh.indices.push_back(idx0);
+      int maxRounds =
-        shape->mesh.indices.push_back(idx1);
+          10;  // arbitrary max loop count to protect against unexpected errors
-        shape->mesh.indices.push_back(idx2);
 
-        shape->mesh.num_face_vertices.push_back(3);
+      face_t remainingFace = face;  // copy
-        shape->mesh.material_ids.push_back(material_id);
+      size_t guess_vert = 0;
+      vertex_index_t ind[3];
+      real_t vx[3];
+      real_t vy[3];
+      while (remainingFace.vertex_indices.size() > 3 && maxRounds > 0) {
+        npolys = remainingFace.vertex_indices.size();
+        if (guess_vert >= npolys) {
+          maxRounds -= 1;
+          guess_vert -= npolys;
+        }
+        for (size_t k = 0; k < 3; k++) {
+          ind[k] = remainingFace.vertex_indices[(guess_vert + k) % npolys];
+          size_t vi = size_t(ind[k].v_idx);
+          vx[k] = v[vi * 3 + axes[0]];
+          vy[k] = v[vi * 3 + axes[1]];
+        }
+        real_t e0x = vx[1] - vx[0];
+        real_t e0y = vy[1] - vy[0];
+        real_t e1x = vx[2] - vx[1];
+        real_t e1y = vy[2] - vy[1];
+        real_t cross = e0x * e1y - e0y * e1x;
+        // if an internal angle
+        if (cross * area < 0.0f) {
+          guess_vert += 1;
+          continue;
+        }
+
+        // check all other verts in case they are inside this triangle
+        bool overlap = false;
+        for (size_t otherVert = 3; otherVert < npolys; ++otherVert) {
+          size_t ovi = size_t(
+              remainingFace.vertex_indices[(guess_vert + otherVert) % npolys]
+                  .v_idx);
+          real_t tx = v[ovi * 3 + axes[0]];
+          real_t ty = v[ovi * 3 + axes[1]];
+          if (pnpoly(3, vx, vy, tx, ty)) {
+            overlap = true;
+            break;
+          }
+        }
+
+        if (overlap) {
+          guess_vert += 1;
+          continue;
+        }
+
+        // this triangle is an ear
+        {
+          index_t idx0, idx1, idx2;
+          idx0.vertex_index = ind[0].v_idx;
+          idx0.normal_index = ind[0].vn_idx;
+          idx0.texcoord_index = ind[0].vt_idx;
+          idx1.vertex_index = ind[1].v_idx;
+          idx1.normal_index = ind[1].vn_idx;
+          idx1.texcoord_index = ind[1].vt_idx;
+          idx2.vertex_index = ind[2].v_idx;
+          idx2.normal_index = ind[2].vn_idx;
+          idx2.texcoord_index = ind[2].vt_idx;
+
+          shape->mesh.indices.push_back(idx0);
+          shape->mesh.indices.push_back(idx1);
+          shape->mesh.indices.push_back(idx2);
+
+          shape->mesh.num_face_vertices.push_back(3);
+          shape->mesh.material_ids.push_back(material_id);
+          shape->mesh.smoothing_group_ids.push_back(face.smoothing_group_id);
+        }
+
+        // remove v1 from the list
+        size_t removed_vert_index = (guess_vert + 1) % npolys;
+        while (removed_vert_index + 1 < npolys) {
+          remainingFace.vertex_indices[removed_vert_index] =
+              remainingFace.vertex_indices[removed_vert_index + 1];
+          removed_vert_index += 1;
+        }
+        remainingFace.vertex_indices.pop_back();
+      }
+
+      if (remainingFace.vertex_indices.size() == 3) {
+        i0 = remainingFace.vertex_indices[0];
+        i1 = remainingFace.vertex_indices[1];
+        i2 = remainingFace.vertex_indices[2];
+        {
+          index_t idx0, idx1, idx2;
+          idx0.vertex_index = i0.v_idx;
+          idx0.normal_index = i0.vn_idx;
+          idx0.texcoord_index = i0.vt_idx;
+          idx1.vertex_index = i1.v_idx;
+          idx1.normal_index = i1.vn_idx;
+          idx1.texcoord_index = i1.vt_idx;
+          idx2.vertex_index = i2.v_idx;
+          idx2.normal_index = i2.vn_idx;
+          idx2.texcoord_index = i2.vt_idx;
+
+          shape->mesh.indices.push_back(idx0);
+          shape->mesh.indices.push_back(idx1);
+          shape->mesh.indices.push_back(idx2);
+
+          shape->mesh.num_face_vertices.push_back(3);
+          shape->mesh.material_ids.push_back(material_id);
+          shape->mesh.smoothing_group_ids.push_back(face.smoothing_group_id);
+        }
       }
     } else {
       for (size_t k = 0; k < npolys; k++) {
         index_t idx;
-        idx.vertex_index = face[k].v_idx;
+        idx.vertex_index = face.vertex_indices[k].v_idx;
-        idx.normal_index = face[k].vn_idx;
+        idx.normal_index = face.vertex_indices[k].vn_idx;
-        idx.texcoord_index = face[k].vt_idx;
+        idx.texcoord_index = face.vertex_indices[k].vt_idx;
         shape->mesh.indices.push_back(idx);
       }
 
       shape->mesh.num_face_vertices.push_back(
           static_cast<unsigned char>(npolys));
       shape->mesh.material_ids.push_back(material_id);  // per face
+      shape->mesh.smoothing_group_ids.push_back(
+          face.smoothing_group_id);  // per face
     }
   }
 
@@ -1533,13 +1711,17 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
   std::vector<real_t> vt;
   std::vector<real_t> vc;
   std::vector<tag_t> tags;
-  std::vector<std::vector<vertex_index> > faceGroup;
+  std::vector<face_t> faceGroup;
   std::string name;
 
   // material
   std::map<std::string, int> material_map;
   int material = -1;
 
+  // smoothing group id
+  unsigned int current_smoothing_id =
+      0;  // Initial value. 0 means no smoothing.
+
   shape_t shape;
 
   std::string linebuf;
@@ -1612,11 +1794,13 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
       token += 2;
       token += strspn(token, " \t");
 
-      std::vector<vertex_index> face;
+      face_t face;
-      face.reserve(3);
+
+      face.smoothing_group_id = current_smoothing_id;
+      face.vertex_indices.reserve(3);
 
       while (!IS_NEW_LINE(token[0])) {
-        vertex_index vi;
+        vertex_index_t vi;
         if (!parseTriple(&token, static_cast<int>(v.size() / 3),
                          static_cast<int>(vn.size() / 3),
                          static_cast<int>(vt.size() / 2), &vi)) {
@@ -1626,14 +1810,13 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
           return false;
         }
 
-        face.push_back(vi);
+        face.vertex_indices.push_back(vi);
         size_t n = strspn(token, " \t\r");
         token += n;
       }
 
       // replace with emplace_back + std::move on C++11
-      faceGroup.push_back(std::vector<vertex_index>());
+      faceGroup.push_back(face);
-      faceGroup[faceGroup.size() - 1].swap(face);
 
       continue;
     }
@@ -1657,7 +1840,7 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
         // this time.
         // just clear `faceGroup` after `exportFaceGroupToShape()` call.
         exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
-                               triangulate);
+                               triangulate, v);
         faceGroup.clear();
         material = newMaterialId;
       }
@@ -1712,7 +1895,7 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
     if (token[0] == 'g' && IS_SPACE((token[1]))) {
       // flush previous face group.
       bool ret = exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
-                                        triangulate);
+                                        triangulate, v);
       (void)ret;  // return value not used.
 
       if (shape.mesh.indices.size() > 0) {
@@ -1749,7 +1932,7 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
     if (token[0] == 'o' && IS_SPACE((token[1]))) {
       // flush previous face group.
       bool ret = exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
-                                        triangulate);
+                                        triangulate, v);
       if (ret) {
         shapes->push_back(shape);
       }
@@ -1793,13 +1976,49 @@ bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
       }
 
       tags.push_back(tag);
+
+      continue;
     }
 
+    if (token[0] == 's' && IS_SPACE(token[1])) {
+      // smoothing group id
+      token += 2;
+
+      // skip space.
+      token += strspn(token, " \t");  // skip space
+
+      if (token[0] == '\0') {
+        continue;
+      }
+
+      if (token[0] == '\r' || token[1] == '\n') {
+        continue;
+      }
+
+      if (strlen(token) >= 3) {
+        if (token[0] == 'o' && token[1] == 'f' && token[2] == 'f') {
+          current_smoothing_id = 0;
+        }
+      } else {
+        // assume number
+        int smGroupId = parseInt(&token);
+        if (smGroupId < 0) {
+          // parse error. force set to 0.
+          // FIXME(syoyo): Report warning.
+          current_smoothing_id = 0;
+        } else {
+          current_smoothing_id = static_cast<unsigned int>(smGroupId);
+        }
+      }
+
+      continue;
+    }  // smoothing group id
+
     // Ignore unknown command.
   }
 
   bool ret = exportFaceGroupToShape(&shape, faceGroup, tags, material, name,
-                                    triangulate);
+                                    triangulate, v);
   // exportFaceGroupToShape return false when `usemtl` is called in the last
   // line.
   // we also add `shape` to `shapes` when `shape.mesh` has already some
@@ -1907,7 +2126,7 @@ bool LoadObjWithCallback(std::istream &inStream, const callback_t &callback,
 
       indices.clear();
       while (!IS_NEW_LINE(token[0])) {
-        vertex_index vi = parseRawTriple(&token);
+        vertex_index_t vi = parseRawTriple(&token);
 
         index_t idx;
         idx.vertex_index = vi.v_idx;
@@ -2100,6 +2319,10 @@ bool LoadObjWithCallback(std::istream &inStream, const callback_t &callback,
 
   return true;
 }
+
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
 }  // namespace tinyobj
 
 #endif