Fix build when using RapidJSON backend.

Minor change to the example of usage with opengl (basic example)

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1 @@
+blank_issues_enabled: false

.github/ISSUE_TEMPLATE/issue-report.md

@@ -0,0 +1,30 @@
+---
+name: Issue report
+about: Create a report
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the issue**
+
+A clear and concise description of what the issue is.
+
+**To Reproduce**
+
+- OS
+- Compiler, compiler version, compile options
+- Please attach minimal and reproducible .glTF file if you got an issue related to .glTF data
+
+**Expected behaviour**
+
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+
+If applicable, add screenshots to help explain your problem.
+
+
+**Additional context**
+Add any other context about the problem here.

README.md

@@ -3,7 +3,7 @@
 `TinyGLTF` is a header only C++11 glTF 2.0 https://github.com/KhronosGroup/glTF library.
 
 `TinyGLTF` uses Niels Lohmann's json library(https://github.com/nlohmann/json), so now it requires C++11 compiler.
-If you are looking for old, C++03 version, please use `devel-picojson` branch.
+If you are looking for old, C++03 version, please use `devel-picojson` branch(but not maintained anymore).
 
 ## Status
 
@@ -13,6 +13,10 @@ If you are looking for old, C++03 version, please use `devel-picojson` branch.
  - v2.1.0 release(Draco support)
  - v2.0.0 release(22 Aug, 2018)!
 
+### Branches
+
+* `sajson` : Use sajson to parse JSON. Parsing only but faster compile time(2x reduction compared to json.hpp and RapidJson)
+
 ## Builds
 
 [![Build Status](https://travis-ci.org/syoyo/tinygltf.svg?branch=devel)](https://travis-ci.org/syoyo/tinygltf)

examples/basic/.gitignore

@@ -1,5 +1,6 @@
 .vs
 Debug
+Release
 x64
 packages
 

examples/basic/basic/basic.vcxproj

@@ -22,32 +22,32 @@
     <VCProjectVersion>15.0</VCProjectVersion>
     <ProjectGuid>{0589AC44-0CF3-40D8-8D89-68393CFD40F3}</ProjectGuid>
     <RootNamespace>basic</RootNamespace>
-    <WindowsTargetPlatformVersion>10.0.17134.0</WindowsTargetPlatformVersion>
+    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="Configuration">
     <ConfigurationType>Application</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v142</PlatformToolset>
     <CharacterSet>MultiByte</CharacterSet>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'" Label="Configuration">
     <ConfigurationType>Application</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v142</PlatformToolset>
     <WholeProgramOptimization>true</WholeProgramOptimization>
     <CharacterSet>MultiByte</CharacterSet>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'" Label="Configuration">
     <ConfigurationType>Application</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v142</PlatformToolset>
     <CharacterSet>MultiByte</CharacterSet>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" Label="Configuration">
     <ConfigurationType>Application</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
-    <PlatformToolset>v141</PlatformToolset>
+    <PlatformToolset>v142</PlatformToolset>
     <WholeProgramOptimization>true</WholeProgramOptimization>
     <CharacterSet>MultiByte</CharacterSet>
   </PropertyGroup>

examples/basic/main.cpp

@@ -329,7 +329,7 @@ static void error_callback(int error, const char *description) {
 }
 
 int main(int argc, char **argv) {
-  std::string filename = "../../models/Cube/Cube.gltf";
+  std::string filename = "../../../models/Cube/Cube.gltf";
 
   if (argc > 1) {
     filename = argv[1];
@@ -341,9 +341,12 @@ int main(int argc, char **argv) {
 
   // Force create OpenGL 3.3
   // NOTE(syoyo): Linux + NVIDIA driver segfaults for some reason? commenting out glfwWindowHint will work.
+  // Note (PE): On laptops with intel hd graphics card you can overcome the segfault by enabling experimental, see below (tested on lenovo thinkpad)
   glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
   glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
   glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+  glewExperimental = GL_TRUE;
+
 #ifdef __APPLE__
   glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
 #endif

examples/dxview/CMakeLists.txt

@@ -0,0 +1,36 @@
+cmake_minimum_required(VERSION 3.5)
+project(dxview)
+
+find_package(glfw3 CONFIG REQUIRED)
+find_package(spdlog CONFIG REQUIRED)
+
+add_executable(dxview
+    src/Viewer.h
+    src/Viewer.cc
+    src/dxview.cc
+)
+
+target_include_directories(dxview
+PRIVATE
+    ../../
+)
+
+target_compile_definitions(dxview
+PRIVATE
+    DXVIEW_SWAP_CHAIN_BUFFER_COUNT=3
+    DXVIEW_RES_DIR=L"${PROJECT_SOURCE_DIR}/res"
+)
+
+target_link_libraries(dxview
+PRIVATE
+    dxgi
+    d3dcompiler
+    d3d12
+    glfw
+    spdlog::spdlog
+)
+
+set_target_properties(dxview
+PROPERTIES
+    CXX_STANDARD 17
+)

examples/dxview/README.md

@@ -0,0 +1,37 @@
+# DirectX glTF Viewer
+
+## Overview
+
+This project was motivated by a lack of sample code demonstrating the graphics API agnostic nature of the glTF specification. The sample code is written using modern C++ and DirectX 12 for the client application.
+
+## Features
+
+* [x] DirectX 12
+* [ ] Loader
+* [ ] Animation
+* [ ] Morph Target
+* [ ] Physical Base Rendering
+* [ ] Environment Map
+
+## Dependencies
+
+* [CMake](https://github.com/Kitware/CMake)
+* [Vcpkg](https://github.com/Microsoft/vcpkg)
+* [GLFW](https://github.com/glfw/glfw)
+* [spdlog](https://github.com/gabime/spdlog)
+
+## Building
+
+### Install dependencies
+
+```
+vcpkg install glfw3:x64-windows
+vcpkg install spdlog:x64-windows
+```
+
+### Generate Project Files
+
+```
+mkdir build
+cmake . -B build -DCMAKE_TOOLCHAIN_FILE=${VCPKG_DIR}/script/buildsystem/vcpkg.cmake
+```

examples/dxview/res/gray.hlsl

@@ -0,0 +1,3 @@
+float4 main() : SV_Target {
+    return float4(0.5, 0.5, 0.5, 1.0);
+}

examples/dxview/res/lighting.hlsl

@@ -0,0 +1,52 @@
+struct RS2PS {
+    float4 position : SV_POSITION;
+
+#ifdef HAS_TEXCOORD_0
+    float2 texcoord_0: TEXCOORD_0;
+#endif
+};
+
+struct TextureInfo {
+    uint textureIndex;
+    uint samplerIndex;
+};
+
+struct PBRMetallicRoughness {
+    float4 baseColorFactor;
+    TextureInfo baseColorTexture;
+    float metallicFactor;
+    float roughnessFactor;
+    TextureInfo metallicRoughnessTexture;
+};
+
+cbuffer Material : register(b2) {
+    PBRMetallicRoughness pbrMetallicRoughness;
+};
+
+Texture2D textures[5] : register(t0);
+SamplerState samplerState[5] : register(s0);
+
+float4 getBaseColor(float2 uv) {
+    float4 baseColor = pbrMetallicRoughness.baseColorFactor;
+
+#ifdef HAS_TEXCOORD_0
+    TextureInfo baseColorTexture = pbrMetallicRoughness.baseColorTexture;
+    if (baseColorTexture.textureIndex >= 0) {
+        baseColor *= textures[baseColorTexture.textureIndex].Sample(samplerState[baseColorTexture.samplerIndex], uv);
+    }
+#endif
+
+    return baseColor;
+}
+
+float4 main(RS2PS input) : SV_Target {
+    float2 uv = float2(0.0, 0.0);
+
+#ifdef HAS_TEXCOORD_0
+    uv = input.texcoord_0;
+#endif
+
+    float4 color = getBaseColor(uv);
+
+    return color;
+}

examples/dxview/res/primitive.hlsl

@@ -0,0 +1,46 @@
+struct IA2VS {
+    float3 position  : POSITION;
+
+#ifdef HAS_NORMAL
+    float3 normal : NORMAL;
+#endif
+
+#ifdef HAS_TANGENT
+    float4 tangent : TANGENT;
+#endif
+
+#ifdef HAS_TEXCOORD_0
+    float2 texcoord_0: TEXCOORD_0;
+#endif
+};
+
+struct VS2RS {
+    float4 position : SV_POSITION;
+
+#ifdef HAS_TEXCOORD_0
+    float2 texcoord_0: TEXCOORD_0;
+#endif
+};
+
+cbuffer Camera : register(b0) {
+    float4x4 V;
+    float4x4 P;
+    float4x4 VP;
+};
+
+cbuffer Node : register(b1) {
+    float4x4 M;
+};
+
+VS2RS main(IA2VS input) {
+    VS2RS output;
+    output.position = mul(float4(input.position, 1.0), M);
+    output.position = mul(output.position, V);
+    output.position = mul(output.position, P);
+
+#ifdef HAS_TEXCOORD_0
+    output.texcoord_0 = input.texcoord_0;
+#endif
+
+    return output;
+}

examples/dxview/src/Viewer.h

@@ -0,0 +1,130 @@
+#ifndef DXVIEW_VIEWER_GUARD
+#define DXVIEW_VIEWER_GUARD
+
+#include <DirectXMath.h>
+#include <d3d12.h>
+#include <dxgi1_6.h>
+#include <tiny_gltf.h>
+#include <wrl.h>
+
+#include <filesystem>
+#include <map>
+#include <string>
+#include <vector>
+
+using Microsoft::WRL::ComPtr;
+
+enum RenderPassType { RENDER_PASS_TYPE_PRESENT = 0, RENDER_PASS_TYPE_COUNT };
+
+struct RenderTarget {
+  ComPtr<ID3D12Resource> pTexture;
+  D3D12_CPU_DESCRIPTOR_HANDLE viewDescriptor;
+};
+
+struct TextureInfo {
+  int32_t textureIndex;
+  int32_t samplerIndex;
+};
+
+struct PBRMetallicRoughness {
+  DirectX::XMFLOAT4 baseColorFactor;
+  TextureInfo baseColorTexture;
+  float metallicFactor;
+  float roughnessFactor;
+  TextureInfo metallicRoughnessTexture;
+};
+
+struct Material {
+  std::string name;
+  D3D12_BLEND_DESC blendDesc;
+  D3D12_RASTERIZER_DESC rasterizerDesc;
+  ComPtr<ID3D12Resource> pBuffer;
+  void* pBufferData;
+  ComPtr<ID3D12DescriptorHeap> pSRVDescriptorHeap;
+  ComPtr<ID3D12DescriptorHeap> pSamplerDescriptorHeap;
+};
+
+struct Attribute {
+  std::string name;
+  DXGI_FORMAT format;
+  D3D12_VERTEX_BUFFER_VIEW vertexBufferView;
+};
+
+struct Primitive {
+  std::vector<Attribute> attributes;
+  uint32_t vertexCount;
+  D3D12_PRIMITIVE_TOPOLOGY primitiveTopology;
+  D3D12_INDEX_BUFFER_VIEW indexBufferView;
+  uint32_t indexCount;
+  Material* pMaterial;
+  ComPtr<ID3D12RootSignature> pRootSignature;
+  ComPtr<ID3D12PipelineState> pPipelineState;
+};
+
+struct Mesh {
+  std::string name;
+  std::vector<Primitive> primitives;
+};
+
+struct Node {
+  DirectX::XMFLOAT4X4 M;
+};
+
+struct Camera {
+  DirectX::XMFLOAT4X4 V;
+  DirectX::XMFLOAT4X4 P;
+  DirectX::XMFLOAT4X4 VP;
+};
+
+class Viewer {
+ public:
+  Viewer(HWND window, tinygltf::Model* pModel);
+
+  void update(double deltaTime);
+  void render(double deltaTime);
+
+ private:
+  void initDirectX(HWND window);
+  void buildRenderTargets();
+  void buildResources();
+  void buildBuffers(std::vector<ComPtr<ID3D12Resource> >* pStagingResources);
+  void buildImages(std::vector<ComPtr<ID3D12Resource> >* pStagingResources);
+  void buildSamplerDescs();
+  void buildMaterials();
+  void buildMeshes();
+  void buildNodes();
+
+  void drawNode(uint64_t nodeIndex);
+
+ private:
+  tinygltf::Model* pModel_;
+  ComPtr<IDXGIFactory1> pFactory_;
+  ComPtr<IDXGIAdapter1> pAdapter_;
+  ComPtr<ID3D12Device> pDevice_;
+  ComPtr<ID3D12CommandQueue> pDirectCommandQueue_;
+  UINT64 directFenceValue_;
+  ComPtr<ID3D12Fence> pDirectFence_;
+  ComPtr<ID3D12CommandQueue> pCopyCommandQueue_;
+  UINT64 copyFenceValue_;
+  ComPtr<ID3D12Fence> pCopyFence_;
+  ComPtr<IDXGISwapChain3> pSwapChain_;
+  ComPtr<ID3D12Resource> pSwapChainBuffers_[DXVIEW_SWAP_CHAIN_BUFFER_COUNT];
+  ComPtr<ID3D12CommandAllocator>
+      pDirectCommandAllocators_[DXVIEW_SWAP_CHAIN_BUFFER_COUNT];
+  ComPtr<ID3D12GraphicsCommandList> pDirectCommandList_;
+  ComPtr<ID3D12CommandAllocator> pCopyCommandAllocator_;
+  ComPtr<ID3D12GraphicsCommandList> pCopyCommandList_;
+  UINT descriptorIncrementSize_[D3D12_DESCRIPTOR_HEAP_TYPE_NUM_TYPES];
+  ComPtr<ID3D12DescriptorHeap>
+      pRTVDescriptorHeaps_[DXVIEW_SWAP_CHAIN_BUFFER_COUNT];
+  std::vector<RenderTarget> renderTargets_[DXVIEW_SWAP_CHAIN_BUFFER_COUNT];
+  std::vector<ComPtr<ID3D12Resource> > pBuffers_;
+  std::vector<ComPtr<ID3D12Resource> > pTextures_;
+  std::vector<D3D12_SAMPLER_DESC> samplerDescs_;
+  std::vector<Material> materials_;
+  std::vector<Mesh> meshes_;
+  std::vector<ComPtr<ID3D12Resource> > pNodeBuffers_;
+  ComPtr<ID3D12Resource> pCameraBuffer_;
+};
+
+#endif

examples/dxview/src/dxview.cc

@@ -0,0 +1,90 @@
+#define GLFW_EXPOSE_NATIVE_WIN32
+#define TINYGLTF_IMPLEMENTATION
+#define STBI_MSC_SECURE_CRT
+#define STB_IMAGE_IMPLEMENTATION
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+
+#include <GLFW/glfw3.h>
+#include <GLFW/glfw3native.h>
+#include <spdlog/spdlog.h>
+#include <tiny_gltf.h>
+
+#undef GLFW_EXPOSE_NATIVE_WIN32
+#undef TINYGLTF_IMPLEMENTATION
+#undef STBI_MSC_SECURE_CRT
+#undef STB_IMAGE_IMPLEMENTATION
+#undef STB_IMAGE_WRITE_IMPLEMENTATION
+
+#include <iostream>
+#include <string>
+
+#include "Viewer.h"
+
+static void onError(int error, const char* message) {
+  spdlog::error("[{}] {}", error, message);
+}
+
+static void onRender(Viewer* pViewer, double deltaTime) {
+  pViewer->update(deltaTime);
+  pViewer->render(deltaTime);
+}
+
+int main(int argc, char* argv[]) {
+  tinygltf::TinyGLTF context;
+
+  tinygltf::Model model;
+  std::string error;
+  std::string warning;
+  if (!context.LoadASCIIFromFile(&model, &error, &warning, argv[1])) {
+    if (!error.empty()) {
+      spdlog::error("{}", error);
+    }
+
+    if (!warning.empty()) {
+      spdlog::warn("{}", warning);
+    }
+
+    exit(EXIT_FAILURE);
+  }
+
+  GLFWwindow* pWindow;
+
+  glfwSetErrorCallback(onError);
+
+  if (!glfwInit()) {
+    spdlog::error("Fail to initialize GLFW!!!");
+    exit(EXIT_FAILURE);
+  }
+
+  glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
+  glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
+
+  pWindow = glfwCreateWindow(512, 512, "dxview", nullptr, nullptr);
+  if (!pWindow) {
+    spdlog::error("Fail to create GLFWwindow!!!");
+    glfwTerminate();
+    exit(EXIT_FAILURE);
+  }
+
+  auto pViewer = std::make_unique<Viewer>(glfwGetWin32Window(pWindow), &model);
+  if (!pViewer) {
+    spdlog::error("Fail to create Viewer");
+    glfwDestroyWindow(pWindow);
+    glfwTerminate();
+    exit(EXIT_FAILURE);
+  }
+
+  auto prevTimeStamp = glfwGetTime();
+  while (!glfwWindowShouldClose(pWindow)) {
+    auto currTimeStamp = glfwGetTime();
+
+    onRender(pViewer.get(), currTimeStamp - prevTimeStamp);
+    prevTimeStamp = currTimeStamp;
+
+    glfwPollEvents();
+  }
+
+  glfwDestroyWindow(pWindow);
+  glfwTerminate();
+  exit(EXIT_SUCCESS);
+}

tests/tester.cc

@@ -3,6 +3,9 @@
 #define STB_IMAGE_WRITE_IMPLEMENTATION
 #include "tiny_gltf.h"
 
+// Nlohmann json(include ../json.hpp)
+#include "json.hpp"
+
 #define CATCH_CONFIG_MAIN  // This tells Catch to provide a main() - only do this in one cpp file
 #include "catch.hpp"
 
@@ -412,6 +415,28 @@ TEST_CASE("image-uri-spaces", "[issue-236]") {
   REQUIRE(true == ret);
 }
 
+TEST_CASE("serialize-empty-material", "[issue-294]") {
+
+  tinygltf::Model m;
+
+  tinygltf::Material mat;
+  mat.pbrMetallicRoughness.baseColorFactor = {1.0f, 1.0f, 1.0f, 1.0f}; // default baseColorFactor
+  m.materials.push_back(mat);
+
+  std::stringstream os;
+
+  tinygltf::TinyGLTF ctx;
+  ctx.WriteGltfSceneToStream(&m, os, false, false);
+
+  // use nlohmann json
+  nlohmann::json j = nlohmann::json::parse(os.str());
+
+  REQUIRE(1 == j["materials"].size());
+  REQUIRE(j["asset"].is_null());
+  REQUIRE(j["materials"][0].is_object());
+
+}
+
 #ifndef TINYGLTF_NO_FS
 TEST_CASE("expandpath-utf-8", "[pr-226]") {
 

tiny_gltf.h

@@ -26,6 +26,7 @@
 // THE SOFTWARE.
 
 // Version:
+//  - v2.4.3 Fix null object output when when material has all default parameters.
 //  - v2.4.2 Decode percent-encoded URI.
 //  - v2.4.1 Fix some glTF object class does not have `extensions` and/or
 //  `extras` property.
@@ -664,6 +665,8 @@ struct Image {
     width = -1;
     height = -1;
     component = -1;
+    bits = -1;
+    pixel_type = -1;
   }
   DEFAULT_METHODS(Image)
 
@@ -996,6 +999,7 @@ struct Primitive {
   Primitive() {
     material = -1;
     indices = -1;
+    mode = -1;
   }
   DEFAULT_METHODS(Primitive)
   bool operator==(const Primitive &) const;
@@ -1249,7 +1253,14 @@ struct FsCallbacks {
 
 bool FileExists(const std::string &abs_filename, void *);
 
-std::string ExpandFilePath(const std::string &filepath, void *);
+///
+/// Expand file path(e.g. `~` to home directory on posix, `%APPDATA%` to
+/// `C:\Users\tinygltf\AppData`)
+///
+/// @param[in] filepath File path string. Assume UTF-8
+/// @param[in] userdata User data. Set to `nullptr` if you don't need it.
+///
+std::string ExpandFilePath(const std::string &filepath, void *userdata);
 
 bool ReadWholeFile(std::vector<unsigned char> *out, std::string *err,
                    const std::string &filepath, void *);
@@ -2486,7 +2497,7 @@ static inline std::wstring UTF8ToWchar(const std::string &str) {
 
 static inline std::string WcharToUTF8(const std::wstring &wstr) {
   int str_size = WideCharToMultiByte(CP_UTF8, 0, wstr.data(), (int)wstr.size(),
-                                      nullptr, 0, NULL, NULL);
+                                     nullptr, 0, NULL, NULL);
   std::string str(str_size, 0);
   WideCharToMultiByte(CP_UTF8, 0, wstr.data(), (int)wstr.size(), &str[0],
                       (int)str.size(), NULL, NULL);
@@ -2629,7 +2640,8 @@ bool ReadWholeFile(std::vector<unsigned char> *out, std::string *err,
   __gnu_cxx::stdio_filebuf<char> wfile_buf(file_descriptor, std::ios_base::in);
   std::istream f(&wfile_buf);
 #elif defined(_MSC_VER) || defined(_LIBCPP_VERSION)
-  // For libcxx, assume _LIBCPP_HAS_OPEN_WITH_WCHAR is defined to accept `wchar_t *`
+  // For libcxx, assume _LIBCPP_HAS_OPEN_WITH_WCHAR is defined to accept
+  // `wchar_t *`
   std::ifstream f(UTF8ToWchar(filepath).c_str(), std::ifstream::binary);
 #else
   // Unknown compiler/runtime
@@ -2991,7 +3003,9 @@ json_const_iterator ObjectEnd(const json &o) {
 #endif
 }
 
-const char *GetKey(json_const_iterator &it) {
+// Making this a const char* results in a pointer to a temporary when
+// TINYGLTF_USE_RAPIDJSON is off.
+std::string GetKey(json_const_iterator &it) {
 #ifdef TINYGLTF_USE_RAPIDJSON
   return it->name.GetString();
 #else
@@ -5696,10 +5710,13 @@ bool TinyGLTF::LoadFromString(Model *model, std::string *err, std::string *warn,
 
       for (auto &target : primitive.targets) {
         for (auto &attribute : target) {
-          model
-              ->bufferViews[size_t(
-                  model->accessors[size_t(attribute.second)].bufferView)]
-              .target = TINYGLTF_TARGET_ARRAY_BUFFER;
+          auto bufferView =
+              model->accessors[size_t(attribute.second)].bufferView;
+          // bufferView could be null(-1) for sparse morph target
+          if (bufferView >= 0) {
+            model->bufferViews[size_t(bufferView)].target =
+                TINYGLTF_TARGET_ARRAY_BUFFER;
+          }
         }
       }
     }
@@ -7209,6 +7226,15 @@ static void SerializeGltfModel(Model *model, json &o) {
     for (unsigned int i = 0; i < model->materials.size(); ++i) {
       json material;
       SerializeGltfMaterial(model->materials[i], material);
+
+      if (JsonIsNull(material)) {
+        // Issue 294.
+        // `material` does not have any required parameters
+        // so the result may be null(unmodified) when all material parameters have default value.
+        //
+        // null is not allowed thus we create an empty JSON object.
+        JsonSetObject(material);
+      }
       JsonPushBack(materials, std::move(material));
     }
     JsonAddMember(o, "materials", std::move(materials));
@@ -7334,8 +7360,9 @@ static void SerializeGltfModel(Model *model, json &o) {
 
     // Also add "KHR_lights_punctual" to `extensionsUsed`
     {
-      auto has_khr_lights_punctual = std::find_if(
-          extensionsUsed.begin(), extensionsUsed.end(), [](const std::string &s) {
+      auto has_khr_lights_punctual =
+          std::find_if(extensionsUsed.begin(), extensionsUsed.end(),
+                       [](const std::string &s) {
                          return (s.compare("KHR_lights_punctual") == 0);
                        });