Add CMake test target and fix Windows test failure

- Add TINYGLTF_BUILD_TESTS option to build unit tests via CMake
- Test runs from tests/ directory so relative paths work correctly
- Fix Windows file sharing violation in images-as-is test by closing
  fstream before stbi_load attempts to open the same file

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/instructions/copilot-instructions.md

@@ -0,0 +1,92 @@
+# Copilot Review Instructions for TinyGLTF
+
+This document provides guidelines for reviewing code changes in the TinyGLTF repository.
+
+## Memory Safety
+
+- **Buffer Overflows**: Check for proper bounds checking when accessing arrays, vectors, and buffers. Verify that buffer sizes are validated before read/write operations.
+- **Null Pointer Dereferences**: Ensure all pointers are checked for null before dereferencing, especially when handling optional glTF fields.
+- **Memory Leaks**: Verify proper resource management, including RAII patterns for file handles, image data, and dynamically allocated memory.
+- **Use-After-Free**: Check for proper lifetime management of objects, especially when dealing with callbacks and asynchronous operations.
+
+## Error Handling
+
+- **File I/O**: Verify that all file operations have proper error checking and meaningful error messages.
+- **JSON Parsing**: Ensure JSON parsing errors are caught and reported with helpful context about the location and nature of the error.
+- **Resource Loading**: Check that failures in loading images, buffers, and other resources are properly handled and don't cause crashes.
+- **Error Propagation**: Verify that errors are properly propagated through the call stack with appropriate error messages.
+
+## glTF 2.0 Specification Compliance
+
+- **Required Fields**: Ensure all required glTF fields are validated and present.
+- **Data Types**: Verify that data types match the glTF specification (e.g., component types, accessor types).
+- **Constraints**: Check that glTF constraints are enforced (e.g., valid ranges for enums, buffer stride requirements).
+- **Extensions**: Verify proper handling of glTF extensions and that unknown extensions are handled gracefully.
+- **Validation**: Ensure new features align with the glTF 2.0 specification from the Khronos Group.
+
+## Cross-Platform Compatibility
+
+- **Windows**: Check for proper handling of Windows-specific issues (path separators, line endings, file operations).
+- **Linux**: Verify compatibility with various Linux distributions and compilers (GCC, Clang).
+- **macOS**: Ensure macOS-specific considerations are addressed (case-sensitive filesystems, Clang compatibility).
+- **Mobile Platforms**: Consider Android and iOS compatibility where applicable.
+- **Endianness**: Verify proper handling of byte order when reading binary data.
+- **Compiler Compatibility**: Ensure code compiles with C++11 standard and supported compilers (MSVC, GCC, Clang).
+
+## Edge Cases in glTF Parsing
+
+- **Empty/Minimal Files**: Verify handling of minimal valid glTF files.
+- **Large Files**: Check for proper handling of large glTF files and buffers without memory exhaustion.
+- **Malformed Data**: Ensure graceful handling of malformed or invalid glTF data.
+- **Missing Optional Fields**: Verify correct behavior when optional glTF fields are absent.
+- **Edge Values**: Check handling of boundary values (e.g., maximum buffer sizes, extreme floating-point values).
+- **Base64 Encoding**: Verify proper handling of base64-encoded data URIs and invalid encodings.
+
+## Backwards Compatibility
+
+- **API Changes**: Ensure public API changes maintain backwards compatibility or are properly deprecated.
+- **Breaking Changes**: Flag any breaking changes for major version updates and document migration paths.
+- **Binary Compatibility**: Consider ABI stability for header-only library changes.
+- **Default Behavior**: Verify that default behavior of existing functionality remains unchanged.
+
+## Performance Considerations
+
+- **Parsing Performance**: Check for unnecessary copies, redundant allocations, and inefficient algorithms in parsing logic.
+- **Memory Usage**: Verify efficient memory usage, especially when loading large glTF files.
+- **I/O Operations**: Ensure efficient file reading and minimize unnecessary disk access.
+- **String Operations**: Check for efficient string handling (use of string_view, move semantics).
+- **STL Usage**: Verify appropriate use of STL containers and algorithms.
+
+## Documentation
+
+- **Public API**: Ensure all public functions, classes, and methods have clear documentation comments.
+- **Parameters**: Verify that function parameters are documented, including expected ranges and constraints.
+- **Return Values**: Document return values and possible error conditions.
+- **Examples**: Check that complex features include usage examples.
+- **Changelog**: Verify that significant changes are documented in release notes or changelog.
+
+## Testing
+
+- **Test Coverage**: Ensure new features include appropriate unit tests or integration tests.
+- **Edge Cases**: Verify that tests cover edge cases and error conditions.
+- **Cross-Platform Tests**: Check that tests run on all supported platforms.
+- **Regression Tests**: Ensure bug fixes include regression tests to prevent recurrence.
+- **Sample Files**: Verify that changes are tested with various valid and invalid glTF sample files.
+
+## Code Style Consistency
+
+- **Header-Only Pattern**: Maintain the header-only library structure.
+- **Naming Conventions**: Follow existing naming conventions (CamelCase for types, snake_case for functions where applicable).
+- **Formatting**: Adhere to the existing code formatting style (check `.clang-format` if available).
+- **Include Guards**: Verify proper include guards and header organization.
+- **Namespace Usage**: Ensure proper use of the `tinygltf` namespace.
+- **Comments**: Maintain consistent comment style with existing code.
+- **C++11 Compliance**: Verify that code uses C++11 features appropriately and doesn't require newer standards unless specified.
+
+## Additional Considerations
+
+- **Third-Party Dependencies**: Minimize new dependencies; prefer existing dependencies (json.hpp, stb_image).
+- **Warnings**: Ensure code compiles without warnings on supported compilers.
+- **const Correctness**: Verify proper use of const for parameters and methods.
+- **RAII**: Prefer RAII patterns for resource management over manual cleanup.
+- **noexcept**: Use noexcept appropriately for move constructors and move assignment operators.

CMakeLists.txt

@@ -14,8 +14,10 @@ option(TINYGLTF_BUILD_LOADER_EXAMPLE "Build loader_example(load glTF and dump in
 option(TINYGLTF_BUILD_GL_EXAMPLES "Build GL exampels(requires glfw, OpenGL, etc)" OFF)
 option(TINYGLTF_BUILD_VALIDATOR_EXAMPLE "Build validator exampe" OFF)
 option(TINYGLTF_BUILD_BUILDER_EXAMPLE "Build glTF builder example" OFF)
+option(TINYGLTF_BUILD_TESTS "Build unit tests" OFF)
 option(TINYGLTF_HEADER_ONLY "On: header-only mode. Off: create tinygltf library(No TINYGLTF_IMPLEMENTATION required in your project)" OFF)
 option(TINYGLTF_INSTALL "Install tinygltf files during install step. Usually set to OFF if you include tinygltf through add_subdirectory()" ON)
+option(TINYGLTF_INSTALL_VENDOR "Install vendored nlohmann/json and nothings/stb headers" ON)
 
 if (TINYGLTF_BUILD_LOADER_EXAMPLE)
   add_executable(loader_example
@@ -36,6 +38,16 @@ if (TINYGLTF_BUILD_BUILDER_EXAMPLE)
   add_subdirectory ( examples/build-gltf )
 endif (TINYGLTF_BUILD_BUILDER_EXAMPLE)
 
+if (TINYGLTF_BUILD_TESTS)
+  enable_testing()
+  add_executable(tester tests/tester.cc)
+  target_include_directories(tester PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}
+    ${CMAKE_CURRENT_SOURCE_DIR}/tests
+  )
+  add_test(NAME tester COMMAND tester WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/tests)
+endif (TINYGLTF_BUILD_TESTS)
+
 #
 # for add_subdirectory and standalone build
 #
@@ -61,19 +73,26 @@ endif (TINYGLTF_HEADER_ONLY)
 
 if (TINYGLTF_INSTALL)
   install(TARGETS tinygltf EXPORT tinygltfTargets)
-  install(EXPORT tinygltfTargets NAMESPACE tinygltf:: FILE TinyGLTFTargets.cmake DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake)
+  install(EXPORT tinygltfTargets NAMESPACE tinygltf:: FILE TinyGLTFTargets.cmake DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/tinygltf)
   configure_package_config_file(${CMAKE_CURRENT_SOURCE_DIR}/cmake/TinyGLTFConfig.cmake.in ${CMAKE_CURRENT_BINARY_DIR}/TinyGLTFConfig.cmake INSTALL_DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake)
-  install(FILES ${CMAKE_CURRENT_BINARY_DIR}/TinyGLTFConfig.cmake DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake)
+  install(FILES ${CMAKE_CURRENT_BINARY_DIR}/TinyGLTFConfig.cmake DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/tinygltf)
   # Do not install .lib even if !TINYGLTF_HEADER_ONLY
 
   INSTALL ( FILES
-    json.hpp
-    stb_image.h
-    stb_image_write.h
     tiny_gltf.h
     ${TINYGLTF_EXTRA_SOUECES}
     DESTINATION
     include
     )
 
+    if(TINYGLTF_INSTALL_VENDOR)
+      INSTALL ( FILES
+        json.hpp
+        stb_image.h
+        stb_image_write.h
+        DESTINATION
+        include
+        )
+    endif()
+
 endif(TINYGLTF_INSTALL)

README.md

@@ -9,7 +9,7 @@ If you are looking for old, C++03 version, please use `devel-picojson` branch (b
 ## Status
 
 Currently TinyGLTF is stable and maintenance mode. No drastic changes and feature additions planned.
-
+ - v2.9.0 Various fixes and improvements. Filesystem callback API change.
  - v2.8.0 Add URICallbacks for custom URI handling in Buffer and Image. PR#397
  - v2.7.0 Change WriteImageDataFunction user callback function signature. PR#393
  - v2.6.0 Support serializing sparse accessor(Thanks to @fynv).
@@ -159,9 +159,10 @@ Model model;
 TinyGLTF loader;
 std::string err;
 std::string warn;
+std::string filename = "input.gltf";
 
-bool ret = loader.LoadASCIIFromFile(&model, &err, &warn, argv[1]);
-//bool ret = loader.LoadBinaryFromFile(&model, &err, &warn, argv[1]); // for binary glTF(.glb)
+bool ret = loader.LoadASCIIFromFile(&model, &err, &warn, filename);
+//bool ret = loader.LoadBinaryFromFile(&model, &err, &warn, filename); // for binary glTF(.glb)
 
 if (!warn.empty()) {
   printf("Warn: %s\n", warn.c_str());
@@ -172,8 +173,7 @@ if (!err.empty()) {
 }
 
 if (!ret) {
-  printf("Failed to parse glTF\n");
-  return -1;
+  printf("Failed to parse glTF: %s\n", filename.c_str());
 }
 ```
 
@@ -194,7 +194,6 @@ if (!ret) {
 * `TINYGLTF_NO_INCLUDE_STB_IMAGE `: Disable including `stb_image.h` from within `tiny_gltf.h` because it has been already included before or you want to include it using custom path before including `tiny_gltf.h`.
 * `TINYGLTF_NO_INCLUDE_STB_IMAGE_WRITE `: Disable including `stb_image_write.h` from within `tiny_gltf.h` because it has been already included before or you want to include it using custom path before including `tiny_gltf.h`.
 * `TINYGLTF_USE_RAPIDJSON` : Use RapidJSON as a JSON parser/serializer. RapidJSON files are not included in TinyGLTF repo. Please set an include path to RapidJSON if you enable this feature.
-* `TINYGLTF_USE_CPP14` : Use C++14 feature(requires C++14 compiler). This may give better performance than C++11.
 
 
 ## CMake options
@@ -211,6 +210,11 @@ set(TINYGLTF_INSTALL OFF CACHE INTERNAL "" FORCE)
 add_subdirectory(/path/to/tinygltf)
 ```
 
+NOTE: Using tinygltf as a submodule doesn't automatically add the headers to your include path (as standard for many libraries). To get this functionality, add the following to the CMakeLists.txt file from above:
+
+```
+target_include_directories(${PROJECT_NAME} PRIVATE "/path/to/tinygltf")
+```
 
 ### Saving gltTF 2.0 model
 

tests/tester.cc

@@ -1121,8 +1121,10 @@ TEST_CASE("images-as-is", "[issue-487]") {
     // All the images should have been written to disk with their original data
     for (const auto& image : model.images)  {
       // Make sure the image files exist
-      std::fstream file(image.uri);
-      CHECK(file.good());
+      {
+        std::fstream file(image.uri);
+        CHECK(file.good());
+      } // Close file before stbi_load (Windows sharing violation fix)
 #ifndef TINYGLTF_NO_STB_IMAGE
       // Make sure we can load the images
       int w = -1, h = -1, component = -1;
@@ -1182,3 +1184,68 @@ TEST_CASE("images-as-is", "[issue-487]") {
     }
   }
 }
+
+TEST_CASE("inverse-bind-matrices-optional", "[issue-492]") {
+  tinygltf::Model model;
+  tinygltf::TinyGLTF ctx;
+  std::string err;
+  std::string warn;
+
+  bool ret = ctx.LoadBinaryFromFile(&model, &err, &warn, "issue-492.glb");
+  if (!warn.empty()) {
+    std::cout << "WARN:" << warn << std::endl;
+  }
+  if (!err.empty()) {
+    std::cerr << "ERR:" << err << std::endl;
+  }
+
+  REQUIRE(true == ret);
+  REQUIRE(err.empty());
+}
+
+bool LoadImageData(tinygltf::Image * /* image */, const int /* image_idx */, std::string * /* err */,
+                   std::string * /* warn */, int /* req_width */, int /* req_height */,
+                   const unsigned char * /* bytes */, int /* size */, void * /*user_data */) {
+    return true;
+}
+
+bool WriteImageData(const std::string * /* basepath */, const std::string * /* filename */,
+                    const tinygltf::Image *image, bool /* embedImages */,
+                    const tinygltf::FsCallbacks * /* fs_cb */, const tinygltf::URICallbacks * /* uri_cb */,
+                    std::string * /* out_uri */, void * user_pointer) {
+    REQUIRE(user_pointer != nullptr);
+    auto counter = static_cast<int*>(user_pointer);
+    *counter = *counter + 1;
+    return true;
+}
+
+TEST_CASE("empty-images-not-written", "[issue-495]") {
+  std::string err;
+  std::string warn;
+  tinygltf::Model model;
+  tinygltf::TinyGLTF ctx;
+
+  ctx.SetImageLoader(LoadImageData, nullptr);
+  bool ok = ctx.LoadASCIIFromFile(&model, &err, &warn, "../models/Cube/Cube.gltf");
+  REQUIRE(ok);
+  REQUIRE(err.empty());
+  REQUIRE(warn.empty());
+
+  CHECK(model.images.size() == 2);
+  for (const auto& image : model.images) {
+    // No data loaded or decoded
+    CHECK(image.image.empty());
+    // The URI is kept
+    CHECK_FALSE(image.uri.empty());
+    // The URI should not be a data URI
+    CHECK(image.uri.find("data:") != 0);
+  }
+
+  // Now write the loaded model
+  int counter = 0;
+  ctx.SetImageWriter(WriteImageData, &counter);
+  ok = ctx.WriteGltfSceneToFile(&model, "issue-495-external.gltf");
+  CHECK(ok);
+  // WriteImageData should be invoked for both images
+  CHECK(counter == 2);
+}

tiny_gltf.h

@@ -50,12 +50,6 @@
 #include <utility>
 #include <vector>
 
-// Auto-detect C++14 standard version
-#if !defined(TINYGLTF_USE_CPP14) && defined(__cplusplus) && \
-    (__cplusplus >= 201402L)
-#define TINYGLTF_USE_CPP14
-#endif
-
 #ifdef __ANDROID__
 #ifdef TINYGLTF_ANDROID_LOAD_FROM_ASSETS
 #include <android/asset_manager.h>
@@ -834,20 +828,20 @@ struct Accessor {
       maxValues;  // optional. integer value is promoted to double
 
   struct Sparse {
-    int count;
-    bool isSparse;
+    int count{0};
+    bool isSparse{false};
     struct {
-      size_t byteOffset;
-      int bufferView;
-      int componentType;  // a TINYGLTF_COMPONENT_TYPE_ value
+      size_t byteOffset{0};
+      int bufferView{-1};
+      int componentType{-1};  // a TINYGLTF_COMPONENT_TYPE_ value
       Value extras;
       ExtensionMap extensions;
       std::string extras_json_string;
       std::string extensions_json_string;
     } indices;
     struct {
-      int bufferView;
-      size_t byteOffset;
+      int bufferView{-1};
+      size_t byteOffset{0};
       Value extras;
       ExtensionMap extensions;
       std::string extras_json_string;
@@ -898,11 +892,7 @@ struct Accessor {
     // unreachable return 0;
   }
 
-  Accessor()
-
-  {
-    sparse.isSparse = false;
-  }
+  Accessor() = default;
   DEFAULT_METHODS(Accessor)
   bool operator==(const tinygltf::Accessor &) const;
 };
@@ -2767,6 +2757,12 @@ bool WriteImageData(const std::string *basepath, const std::string *filename,
                     const Image *image, bool embedImages,
                     const FsCallbacks* fs_cb, const URICallbacks *uri_cb,
                     std::string *out_uri, void *) {
+  // Early out on empty images, report the original uri if the image was not written.
+  if (image->image.empty()) {
+    *out_uri = *filename;
+    return true;
+  }
+
   const std::string ext = GetFilePathExtension(*filename);
 
   // Write image to temporary buffer
@@ -3309,11 +3305,12 @@ static bool UpdateImageObject(const Image &image, std::string &baseDir,
     filename = std::to_string(index) + "." + ext;
   }
 
-  // If callback is set and image data exists, modify image data object. If
-  // image data does not exist, this is not considered a failure and the
-  // original uri should be maintained.
+  // If callback is set, modify image data object.
+  // Note that the callback is also invoked for images without data.
+  // The default callback implementation simply returns true for
+  // empty images and sets the out URI to filename.
   bool imageWritten = false;
-  if (WriteImageData != nullptr && !filename.empty() && !image.image.empty()) {
+  if (WriteImageData != nullptr && !filename.empty()) {
     imageWritten = WriteImageData(&baseDir, &filename, &image, embedImages,
                                   fs_cb, uri_cb, out_uri, user_data);
     if (!imageWritten) {
@@ -4355,7 +4352,7 @@ static bool ParseImage(Image *image, const int image_idx, std::string *err,
     // Just only save some information here. Loading actual image data from
     // bufferView is done after this `ParseImage` function.
     image->bufferView = bufferView;
-    image->mimeType = mime_type;
+    image->mimeType = std::move( mime_type );
     image->width = width;
     image->height = height;
 
@@ -4387,7 +4384,7 @@ static bool ParseImage(Image *image, const int image_idx, std::string *err,
     }
   } else {
     // Assume external file
-    // Keep texture path (for textures that cannot be decoded)
+    // Unconditionally keep the external URI of the image
     image->uri = uri;
 #ifdef TINYGLTF_NO_EXTERNAL_IMAGE
     return true;
@@ -4434,6 +4431,7 @@ static bool ParseImage(Image *image, const int image_idx, std::string *err,
     }
     return false;
   }
+
   return LoadImageData(image, image_idx, err, warn, 0, 0, &img.at(0),
                        static_cast<int>(img.size()), load_image_user_data);
 }
@@ -5253,7 +5251,7 @@ static bool ParseNode(Node *node, std::string *err, const detail::json &o,
   if (node->extensions.count("MSFT_lod") != 0) {
     auto const &msft_lod_ext = node->extensions["MSFT_lod"];
     if (msft_lod_ext.Has("ids")) {
-      auto idsArr = msft_lod_ext.Get("ids");
+      const auto &idsArr = msft_lod_ext.Get("ids");
       for (size_t i = 0; i < idsArr.ArrayLen(); ++i) {
         node->lods.emplace_back(idsArr.Get(i).GetNumberAsInt());
       }
@@ -5282,7 +5280,7 @@ static bool ParseScene(Scene *scene, std::string *err, const detail::json &o,
   if (scene->extensions.count("KHR_audio") != 0) {
     auto const &audio_ext = scene->extensions["KHR_audio"];
     if (audio_ext.Has("emitters")) {
-      auto emittersArr = audio_ext.Get("emitters");
+      const auto &emittersArr = audio_ext.Get("emitters");
       for (size_t i = 0; i < emittersArr.ArrayLen(); ++i) {
         scene->audioEmitters.emplace_back(emittersArr.Get(i).GetNumberAsInt());
       }
@@ -5318,7 +5316,7 @@ static bool ParsePbrMetallicRoughness(
       }
       return false;
     }
-    pbr->baseColorFactor = baseColorFactor;
+    pbr->baseColorFactor = std::move( baseColorFactor );
   }
 
   {
@@ -5470,7 +5468,7 @@ static bool ParseMaterial(Material *material, std::string *err, std::string *war
   if (material->extensions.count("MSFT_lod") != 0) {
     auto const &msft_lod_ext = material->extensions["MSFT_lod"];
     if (msft_lod_ext.Has("ids")) {
-      auto idsArr = msft_lod_ext.Get("ids");
+      const auto &idsArr = msft_lod_ext.Get("ids");
       for (size_t i = 0; i < idsArr.ArrayLen(); ++i) {
         material->lods.emplace_back(idsArr.Get(i).GetNumberAsInt());
       }
@@ -5597,7 +5595,7 @@ static bool ParseAnimation(Animation *animation, std::string *err,
         }
         sampler.input = inputIndex;
         sampler.output = outputIndex;
-        ParseExtrasAndExtensions(&sampler, err, o,
+        ParseExtrasAndExtensions(&sampler, err, s,
                                  store_original_json_for_extras_and_extensions);
 
         animation->samplers.emplace_back(std::move(sampler));
@@ -5660,7 +5658,7 @@ static bool ParseSkin(Skin *skin, std::string *err, const detail::json &o,
   skin->skeleton = skeleton;
 
   int invBind = -1;
-  ParseIntegerProperty(&invBind, err, o, "inverseBindMatrices", true, "Skin");
+  ParseIntegerProperty(&invBind, err, o, "inverseBindMatrices", false, "Skin");
   skin->inverseBindMatrices = invBind;
 
   ParseExtrasAndExtensions(skin, err, o,
@@ -6108,16 +6106,8 @@ bool TinyGLTF::LoadFromString(Model *model, std::string *err, std::string *warn,
     }
   }
 
-  model->buffers.clear();
-  model->bufferViews.clear();
-  model->accessors.clear();
-  model->meshes.clear();
-  model->cameras.clear();
-  model->nodes.clear();
-  model->extensionsUsed.clear();
-  model->extensionsRequired.clear();
-  model->extensions.clear();
-  model->defaultScene = -1;
+  // Reset the model
+  (*model) = Model();
 
   // 1. Parse Asset
   {
@@ -6453,6 +6443,15 @@ bool TinyGLTF::LoadFromString(Model *model, std::string *err, std::string *warn,
           return false;
         }
         const Buffer &buffer = model->buffers[size_t(bufferView.buffer)];
+        if (bufferView.byteOffset >= buffer.data.size()) {
+          if (err) {
+            std::stringstream ss;
+            ss << "image[" << idx << "] bufferView \"" << image.bufferView
+               << "\" indexed out of bounds of its buffer." << std::endl;
+            (*err) += ss.str();
+          }
+          return false;
+        }
 
         if (LoadImageData == nullptr) {
           if (err) {
@@ -7207,6 +7206,7 @@ static void SerializeGltfBufferData(const std::vector<unsigned char> &data,
 
 static bool SerializeGltfBufferData(const std::vector<unsigned char> &data,
                                     const std::string &binFilename) {
+#ifndef TINYGLTF_NO_FS
 #ifdef _WIN32
 #if defined(__GLIBCXX__)  // mingw
   int file_descriptor = _wopen(UTF8ToWchar(binFilename).c_str(),
@@ -7235,6 +7235,9 @@ static bool SerializeGltfBufferData(const std::vector<unsigned char> &data,
     // write empty file.
   }
   return true;
+#else
+  return false;
+#endif
 }
 
 #if 0  // FIXME(syoyo): not used. will be removed in the future release.
@@ -8456,6 +8459,7 @@ static bool WriteGltfStream(std::ostream &stream, const std::string &content) {
 
 static bool WriteGltfFile(const std::string &output,
                           const std::string &content) {
+#ifndef TINYGLTF_NO_FS
 #ifdef _WIN32
 #if defined(_MSC_VER)
   std::ofstream gltfFile(UTF8ToWchar(output).c_str());
@@ -8475,6 +8479,9 @@ static bool WriteGltfFile(const std::string &output,
   if (!gltfFile.is_open()) return false;
 #endif
   return WriteGltfStream(gltfFile, content);
+#else
+    return false;
+#endif
 }
 
 static bool WriteBinaryGltfStream(std::ostream &stream,
@@ -8541,6 +8548,7 @@ static bool WriteBinaryGltfStream(std::ostream &stream,
 static bool WriteBinaryGltfFile(const std::string &output,
                                 const std::string &content,
                                 const std::vector<unsigned char> &binBuffer) {
+#ifndef TINYGLTF_NO_FS
 #ifdef _WIN32
 #if defined(_MSC_VER)
   std::ofstream gltfFile(UTF8ToWchar(output).c_str(), std::ios::binary);
@@ -8557,6 +8565,9 @@ static bool WriteBinaryGltfFile(const std::string &output,
   std::ofstream gltfFile(output.c_str(), std::ios::binary);
 #endif
   return WriteBinaryGltfStream(gltfFile, content, binBuffer);
+#else
+    return false;
+#endif
 }
 
 bool TinyGLTF::WriteGltfSceneToStream(const Model *model, std::ostream &stream,