tinyobjloader · Ybalrid · Jul 5, 2019 · Jul 5, 2019 · Jul 7, 2019 · Jul 7, 2019
diff --git a/tiny_obj_loader.h b/tiny_obj_loader.h
@@ -546,6 +546,40 @@ class ObjReader {
   std::string error_;
 };
 
+class ObjWriter {
+ public:
+  ObjWriter() {}
+
+  /// Construct a writer from a reader
+  ObjWriter(const ObjReader &other);
+
+  ///\brief Save the content of this obj asset to a pair of strings representing
+  /// the OBJ and MLT file contents
+  bool SaveToString(std::string &obj_text, std::string &mlt_text);
+
+  /// Save the content to the file path
+  /// \param file_path The path where to save the file WITHOUT EXTENSION
+  bool SaveTofile(const std::string &file_path);
+
+  ///
+  /// Warning message(may be filled after `save`)
+  ///
+  const std::string &Warning() const;
+
+  ///
+  /// Error message(filled when `save` failed)
+  ///
+  const std::string &error() const;
+
+  attrib_t attrib_;
+  std::vector<shape_t> shapes_;
+  std::vector<material_t> materials_;
+
+ private:
+  std::string warning_;
+  std::string error_;
+};
+
 /// ==>>========= Legacy v1 API =============================================
 
 /// Loads .obj from a file.
@@ -616,11 +650,12 @@ bool ParseTextureNameAndOption(std::string *texname, texture_option_t *texopt,
 #include <cstddef>
 #include <cstdlib>
 #include <cstring>
-#include <limits>
-#include <utility>
-
 #include <fstream>
+#include <iostream>
+#include <limits>
 #include <sstream>
+#include <string>
+#include <utility>
 
 namespace tinyobj {
 
@@ -2060,6 +2095,98 @@ bool MaterialStreamReader::operator()(const std::string &matId,
   return true;
 }
 
+ObjWriter::ObjWriter(const ObjReader &other) {
+  attrib_ = other.GetAttrib();
+  shapes_ = other.GetShapes();
+  materials_ = other.GetMaterials();
+  warning_.clear();
+  error_.clear();
+}
+
+bool ObjWriter::SaveToString(std::string &obj_text, std::string &mlt_text) {
+  // Write the Obj text
+  std::stringstream obj_text_stream;
+  obj_text_stream << "#File created by experimental tiny_obj serializer\n";
+  const size_t vertex_count = attrib_.vertices.size() / 3;
+  for (size_t v = 0; v < vertex_count; v++) {
+    obj_text_stream << "v ";
+    obj_text_stream << attrib_.vertices[3 * v + 0] << " ";
+    obj_text_stream << attrib_.vertices[3 * v + 1] << " ";
+    obj_text_stream << attrib_.vertices[3 * v + 2] << "\n";
+  }
+
+  for (size_t v = 0; v < vertex_count; v++) {
+    obj_text_stream << "vt ";
+    obj_text_stream << attrib_.texcoords[2 * v + 0] << " ";
+    obj_text_stream << attrib_.texcoords[2 * v + 1] << "\n";
+    // obj_text_stream << attrib_.texcoord_ws[v] << "\n";
+  }
+
+  for (size_t v = 0; v < vertex_count; v++) {
+    obj_text_stream << "vn ";
+    obj_text_stream << attrib_.normals[3 * v + 0] << " ";
+    obj_text_stream << attrib_.normals[3 * v + 1] << " ";
+    obj_text_stream << attrib_.normals[3 * v + 2] << "\n";
+  }
+
+  // faces
+  for (size_t s = 0; s < shapes_.size(); ++s) {
+    const shape_t &shape = shapes_[s];
+    const unsigned char face_count =
+        static_cast<unsigned char>(shape.mesh.num_face_vertices.size());
+
+    size_t index_offset = 0;
+    for (size_t f = 0; f < face_count; f++) {
+      obj_text_stream << "f ";
+      const unsigned char face_vertex_count = shape.mesh.num_face_vertices[f];
+      for (size_t v = 0; v < face_vertex_count; ++v) {
+        const index_t index = shape.mesh.indices[index_offset + v];
+        obj_text_stream << index.vertex_index << "/" << index.texcoord_index
+                        << "/" << index.normal_index << " ";
+      }
+      obj_text_stream << "\n";
+      index_offset += face_vertex_count;
+    }
+  }
+
+  obj_text = obj_text_stream.str();
+
+  // TODO write material
+  (void)mlt_text;
+
+  return true;
+}
+
+bool ObjWriter::SaveTofile(const std::string &file_path) {
+  std::string obj_path, mlt_path;
+  obj_path = mlt_path = file_path;
+  obj_path += ".obj";
+  mlt_path += ".mlt";
+
+  std::string obj_text, mlt_text;
+
+  if (!SaveToString(obj_text, mlt_text)) {
+    return false;
+  }
+
+  std::ofstream obj_output(obj_path.c_str());
+  std::ofstream mlt_output(mlt_path.c_str());
+
+  if (!(obj_output && mlt_output)) {
+    error_ = "Could not open output files " + obj_path + " and/or " + mlt_path;
+    return false;
+  }
+
+  obj_output << obj_text;
+  mlt_output << mlt_text;
+
+  return true;
+}
+
+const std::string &ObjWriter::Warning() const { return warning_; }
+
+const std::string &ObjWriter::error() const { return error_; }
+
 bool LoadObj(attrib_t *attrib, std::vector<shape_t> *shapes,
              std::vector<material_t> *materials, std::string *warn,
              std::string *err, const char *filename, const char *mtl_basedir,