Use TINYGLTF_ENABLE_SERIALIZER ifdef to enable/disable serialization code.

README.md

diff --git a/README.md b/README.md
index e9b4134..0b9d4c5 100644
--- a/README.md
+++ b/README.md
@@ -153,6 +153,7 @@
 
 ## Compile options
 
+* `TINYGLTF_ENABLE_SERIALIZER` : Enable glTF serialization feature.
 * `TINYGLTF_NOEXCEPTION` : Disable C++ exception in JSON parsing. You can use `-fno-exceptions` or by defining the symbol `JSON_NOEXCEPTION` and `TINYGLTF_NOEXCEPTION`  to fully remove C++ exception codes when compiling TinyGLTF.
 * `TINYGLTF_NO_STB_IMAGE` : Do not load images with stb_image. Instead use `TinyGLTF::SetImageLoader(LoadimageDataFunction LoadImageData, void *user_data)` to set a callback for loading images.
 * `TINYGLTF_NO_STB_IMAGE_WRITE` : Do not write images with stb_image_write. Instead use `TinyGLTF::SetImageWriter(WriteimageDataFunction WriteImageData, void *user_data)` to set a callback for writing images.

tiny_gltf.h

diff --git a/tiny_gltf.h b/tiny_gltf.h
index fa16ec5..8025202 100644
--- a/tiny_gltf.h
+++ b/tiny_gltf.h
@@ -26,6 +26,7 @@
 // THE SOFTWARE.
 
 // Version:
+//  - v2.4.3 Introduce TINYGLTF_ENABLE_SERIALIZER.
 //  - v2.4.2 Decode percent-encoded URI.
 //  - v2.4.1 Fix some glTF object class does not have `extensions` and/or
 //  `extras` property.
@@ -1323,6 +1324,8 @@
                             const std::string &base_dir = "",
                             unsigned int check_sections = REQUIRE_VERSION);
 
+#if defined(TINYGLTF_ENABLE_SERIALIZER)
+
   ///
   /// Write glTF to stream, buffers and images will be embeded
   ///
@@ -1336,16 +1339,22 @@
                             bool embedImages, bool embedBuffers,
                             bool prettyPrint, bool writeBinary);
 
+#endif
+
   ///
   /// Set callback to use for loading image data
   ///
   void SetImageLoader(LoadImageDataFunction LoadImageData, void *user_data);
 
+#if defined(TINYGLTF_ENABLE_SERIALIZER)
+
   ///
   /// Set callback to use for writing image data
   ///
   void SetImageWriter(WriteImageDataFunction WriteImageData, void *user_data);
 
+#endif
+
   ///
   /// Set callbacks to use for filesystem (fs) access and their user data
   ///
@@ -2393,11 +2402,15 @@
 }
 #endif
 
+#if defined(TINYGLTF_ENABLE_SERIALIZER)
+
 void TinyGLTF::SetImageWriter(WriteImageDataFunction func, void *user_data) {
   WriteImageData = func;
   write_image_user_data_ = user_data;
 }
 
+#endif
+
 #ifndef TINYGLTF_NO_STB_IMAGE_WRITE
 static void WriteToMemory_stbi(void *context, void *data, int size) {
   std::vector<unsigned char> *buffer =
@@ -6214,6 +6227,8 @@
   return ret;
 }
 
+#if defined(TINYGLTF_ENABLE_SERIALIZER)
+
 ///////////////////////
 // GLTF Serialization
 ///////////////////////
@@ -7619,6 +7634,8 @@
   return true;
 }
 
+#endif // TINYGLTF_ENABLE_SERIALIZER
+
 }  // namespace tinygltf
 
 #ifdef __clang__