Fix non-KTX texture was not handled correctly.

Experience file drop API of glfw(not working yet).

LICENSE.tinyktx

@@ -0,0 +1,25 @@
+BSD 2-Clause License
+
+Copyright (c) 2019, DeanoC
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

@@ -7,6 +7,7 @@ If you are looking for old, C++03 version, please use `devel-picojson` branch.
 
 ## Status
 
+ - v2.3.0 release(Support loading KTX image through tiny_ktx)
  - v2.2.0 release(Support loading 16bit PNG. Sparse accessor support)
  - v2.1.0 release(Draco support)
  - v2.0.0 release(22 Aug, 2018)!
@@ -52,7 +53,8 @@ If you are looking for old, C++03 version, please use `devel-picojson` branch.
   * [x] Image load
   * [x] Image save
 * Extensions
-  * [x] Draco mesh decoding
+  * [x] Draco mesh decoding(`TINYGLTF_ENABLE_DRACO` required)
+  * [x] KTX image support(no mipmap. `TINYGLTF_ENABLE_KTX` required)
 
 ## Examples
 
@@ -81,6 +83,7 @@ If you are looking for old, C++03 version, please use `devel-picojson` branch.
   * [ ] OpenEXR extension through TinyEXR.
 * [ ] 16bit PNG support in Serialization
 * [ ] Write example and tests for `animation` and `skin`
+* [ ] mipmap support for KTX image.
 
 ## Licenses
 
@@ -92,12 +95,15 @@ TinyGLTF uses the following third party libraries.
 * base64 : Copyright (C) 2004-2008 René Nyffenegger
 * stb_image.h : v2.08 - public domain image loader - [Github link](https://github.com/nothings/stb/blob/master/stb_image.h)
 * stb_image_write.h : v1.09 - public domain image writer - [Github link](https://github.com/nothings/stb/blob/master/stb_image_write.h)
+* tinyktx.h : Copyright (c) 2019, DeanoC. Licensed under 2 clause BSD license.
 
 
 ## Build and example
 
 Copy `stb_image.h`, `stb_image_write.h`, `json.hpp` and `tiny_gltf.h` to your project.
 
+If you enable KTX support(`TINYGLTF_ENABLE_KTX`), Copy `tinyktx.h` to your project.
+
 ### Loading glTF 2.0 model
 
 ```c++
@@ -143,6 +149,8 @@ if (!ret) {
 * `TINYGLTF_NO_INCLUDE_JSON `: Disable including `json.hpp` 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 `: 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_ENABLE_KTX` : Enable loading KTX images( https://www.khronos.org/opengles/sdk/tools/KTX/ ) using `tiny_ktx.h`. Supported MIME is `image/ktx` ( https://github.com/KhronosGroup/glTF/issues/835 ). See `models/Cube-KTX` for details. Application also defined `TINYKTX_IMPLEMENTATION` in **one** .cc file.
+  * `TINYGLTF_NO_INCLUDE_TINYKTX` : Disable including `tinyktx.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`.
 
 
 ### Saving gltTF 2.0 model
@@ -181,8 +189,6 @@ $ ./tester
 $ ./tester_noexcept
 ```
 
-## Third party licenses
+## Third party licenses used in unit tests
 
-* json.hpp : Licensed under the MIT License <http://opensource.org/licenses/MIT>. Copyright (c) 2013-2017 Niels Lohmann <http://nlohmann.me>.
-* stb_image : Public domain.
 * catch : Copyright (c) 2012 Two Blue Cubes Ltd. All rights reserved. Distributed under the Boost Software License, Version 1.0.

examples/basic/main.cpp

@@ -1,365 +1,460 @@
-#include <fstream>
-#include <iostream>
-
-#include <GL/glew.h>
-#include <GLFW/glfw3.h>
-#include <glm/gtc/matrix_transform.hpp>
-
-#include "shaders.h"
-#include "window.h"
-
-#define TINYGLTF_IMPLEMENTATION
-#define STB_IMAGE_IMPLEMENTATION
-#define STB_IMAGE_WRITE_IMPLEMENTATION
-#define TINYGLTF_NOEXCEPTION
-#define JSON_NOEXCEPTION
-#include "../../tiny_gltf.h"
-
-#define BUFFER_OFFSET(i) ((char *)NULL + (i))
-
-bool loadModel(tinygltf::Model &model, const char *filename) {
-  tinygltf::TinyGLTF loader;
-  std::string err;
-  std::string warn;
-
-  bool res = loader.LoadASCIIFromFile(&model, &err, &warn, filename);
-  if (!warn.empty()) {
-    std::cout << "WARN: " << warn << std::endl;
-  }
-
-  if (!err.empty()) {
-    std::cout << "ERR: " << err << std::endl;
-  }
-
-  if (!res)
-    std::cout << "Failed to load glTF: " << filename << std::endl;
-  else
-    std::cout << "Loaded glTF: " << filename << std::endl;
-
-  return res;
-}
-
-std::map<int, GLuint> bindMesh(std::map<int, GLuint> vbos,
-                               tinygltf::Model &model, tinygltf::Mesh &mesh) {
-  for (size_t i = 0; i < model.bufferViews.size(); ++i) {
-    const tinygltf::BufferView &bufferView = model.bufferViews[i];
-    if (bufferView.target == 0) {  // TODO impl drawarrays
-      std::cout << "WARN: bufferView.target is zero" << std::endl;
-      continue;  // Unsupported bufferView.
-                 /*
-                   From spec2.0 readme:
-                   https://github.com/KhronosGroup/glTF/tree/master/specification/2.0
-                            ... drawArrays function should be used with a count equal to
-                   the count            property of any of the accessors referenced by the
-                   attributes            property            (they are all equal for a given
-                   primitive).
-                 */
-    }
-
-    tinygltf::Buffer buffer = model.buffers[bufferView.buffer];
-    std::cout << "bufferview.target " << bufferView.target << std::endl;
-
-    GLuint vbo;
-    glGenBuffers(1, &vbo);
-    vbos[i] = vbo;
-    glBindBuffer(bufferView.target, vbo);
-
-    std::cout << "buffer.data.size = " << buffer.data.size()
-              << ", bufferview.byteOffset = " << bufferView.byteOffset
-              << std::endl;
-
-    glBufferData(bufferView.target, bufferView.byteLength,
-                 &buffer.data.at(0) + bufferView.byteOffset, GL_STATIC_DRAW);
-  }
-
-  for (size_t i = 0; i < mesh.primitives.size(); ++i) {
-    tinygltf::Primitive primitive = mesh.primitives[i];
-    tinygltf::Accessor indexAccessor = model.accessors[primitive.indices];
-
-    for (auto &attrib : primitive.attributes) {
-      tinygltf::Accessor accessor = model.accessors[attrib.second];
-      int byteStride =
-          accessor.ByteStride(model.bufferViews[accessor.bufferView]);
-      glBindBuffer(GL_ARRAY_BUFFER, vbos[accessor.bufferView]);
-
-      int size = 1;
-      if (accessor.type != TINYGLTF_TYPE_SCALAR) {
-        size = accessor.type;
-      }
-
-      int vaa = -1;
-      if (attrib.first.compare("POSITION") == 0) vaa = 0;
-      if (attrib.first.compare("NORMAL") == 0) vaa = 1;
-      if (attrib.first.compare("TEXCOORD_0") == 0) vaa = 2;
-      if (vaa > -1) {
-        glEnableVertexAttribArray(vaa);
-        glVertexAttribPointer(vaa, size, accessor.componentType,
-                              accessor.normalized ? GL_TRUE : GL_FALSE,
-                              byteStride, BUFFER_OFFSET(accessor.byteOffset));
-      } else
-        std::cout << "vaa missing: " << attrib.first << std::endl;
-    }
-
-    GLuint texid;
-    glGenTextures(1, &texid);
-
-    tinygltf::Texture &tex = model.textures[0];
-    tinygltf::Image &image = model.images[tex.source];
-
-    glBindTexture(GL_TEXTURE_2D, texid);
-    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
-    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
-
-    GLenum format = GL_RGBA;
-
-    if (image.component == 1) {
-      format = GL_RED;
-    } else if (image.component == 2) {
-      format = GL_RG;
-    } else if (image.component == 3) {
-      format = GL_RGB;
-    } else {
-      // ???
-    }
-
-    GLenum type = GL_UNSIGNED_BYTE;
-    if (image.bits == 8) {
-      // ok
-    } else if (image.bits == 16) {
-      type = GL_UNSIGNED_SHORT;
-    } else {
-      // ???
-    }
-
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image.width, image.height, 0,
-                 format, type, &image.image.at(0));
-  }
-
-  return vbos;
-}
-
-// bind models
-void bindModelNodes(std::map<int, GLuint> vbos, tinygltf::Model &model,
-                    tinygltf::Node &node) {
-  bindMesh(vbos, model, model.meshes[node.mesh]);
-  for (size_t i = 0; i < node.children.size(); i++) {
-    bindModelNodes(vbos, model, model.nodes[node.children[i]]);
-  }
-}
-GLuint bindModel(tinygltf::Model &model) {
-  std::map<int, GLuint> vbos;
-  GLuint vao;
-  glGenVertexArrays(1, &vao);
-  glBindVertexArray(vao);
-
-  const tinygltf::Scene &scene = model.scenes[model.defaultScene];
-  for (size_t i = 0; i < scene.nodes.size(); ++i) {
-    bindModelNodes(vbos, model, model.nodes[scene.nodes[i]]);
-  }
-
-  glBindVertexArray(0);
-  // cleanup vbos
-  for (size_t i = 0; i < vbos.size(); ++i) {
-    glDeleteBuffers(1, &vbos[i]);
-  }
-
-  return vao;
-}
-
-void drawMesh(tinygltf::Model &model, tinygltf::Mesh &mesh) {
-  for (size_t i = 0; i < mesh.primitives.size(); ++i) {
-    tinygltf::Primitive primitive = mesh.primitives[i];
-    tinygltf::Accessor indexAccessor = model.accessors[primitive.indices];
-
-    glDrawElements(primitive.mode, indexAccessor.count,
-                   indexAccessor.componentType,
-                   BUFFER_OFFSET(indexAccessor.byteOffset));
-  }
-}
-
-// recursively draw node and children nodes of model
-void drawModelNodes(tinygltf::Model &model, tinygltf::Node &node) {
-  drawMesh(model, model.meshes[node.mesh]);
-  for (size_t i = 0; i < node.children.size(); i++) {
-    drawModelNodes(model, model.nodes[node.children[i]]);
-  }
-}
-void drawModel(GLuint vao, tinygltf::Model &model) {
-  glBindVertexArray(vao);
-
-  const tinygltf::Scene &scene = model.scenes[model.defaultScene];
-  for (size_t i = 0; i < scene.nodes.size(); ++i) {
-    drawModelNodes(model, model.nodes[scene.nodes[i]]);
-  }
-
-  glBindVertexArray(0);
-}
-
-void dbgModel(tinygltf::Model &model) {
-  for (auto &mesh : model.meshes) {
-    std::cout << "mesh : " << mesh.name << std::endl;
-    for (auto &primitive : mesh.primitives) {
-      const tinygltf::Accessor &indexAccessor =
-          model.accessors[primitive.indices];
-
-      std::cout << "indexaccessor: count " << indexAccessor.count << ", type "
-                << indexAccessor.componentType << std::endl;
-
-      tinygltf::Material &mat = model.materials[primitive.material];
-      for (auto &mats : mat.values) {
-        std::cout << "mat : " << mats.first.c_str() << std::endl;
-      }
-
-      for (auto &image : model.images) {
-        std::cout << "image name : " << image.uri << std::endl;
-        std::cout << "  size : " << image.image.size() << std::endl;
-        std::cout << "  w/h : " << image.width << "/" << image.height
-                  << std::endl;
-      }
-
-      std::cout << "indices : " << primitive.indices << std::endl;
-      std::cout << "mode     : "
-                << "(" << primitive.mode << ")" << std::endl;
-
-      for (auto &attrib : primitive.attributes) {
-        std::cout << "attribute : " << attrib.first.c_str() << std::endl;
-      }
-    }
-  }
-}
-
-glm::mat4 genView(glm::vec3 pos, glm::vec3 lookat) {
-  // Camera matrix
-  glm::mat4 view = glm::lookAt(
-      pos,                // Camera in World Space
-      lookat,             // and looks at the origin
-      glm::vec3(0, 1, 0)  // Head is up (set to 0,-1,0 to look upside-down)
-  );
-
-  return view;
-}
-
-glm::mat4 genMVP(glm::mat4 view_mat, glm::mat4 model_mat, float fov, int w,
-                 int h) {
-  glm::mat4 Projection =
-      glm::perspective(glm::radians(fov), (float)w / (float)h, 0.01f, 1000.0f);
-
-  // Or, for an ortho camera :
-  // glm::mat4 Projection = glm::ortho(-10.0f,10.0f,-10.0f,10.0f,0.0f,100.0f);
-  // // In world coordinates
-
-  glm::mat4 mvp = Projection * view_mat * model_mat;
-
-  return mvp;
-}
-
-void displayLoop(Window &window, const std::string &filename) {
-  Shaders shader = Shaders();
-  glUseProgram(shader.pid);
-
-  // grab uniforms to modify
-  GLuint MVP_u = glGetUniformLocation(shader.pid, "MVP");
-  GLuint sun_position_u = glGetUniformLocation(shader.pid, "sun_position");
-  GLuint sun_color_u = glGetUniformLocation(shader.pid, "sun_color");
-
-  tinygltf::Model model;
-  if (!loadModel(model, filename.c_str())) return;
-
-  GLuint vao = bindModel(model);
-  // dbgModel(model); return;
-
-  // Model matrix : an identity matrix (model will be at the origin)
-  glm::mat4 model_mat = glm::mat4(1.0f);
-  glm::mat4 model_rot = glm::mat4(1.0f);
-  glm::vec3 model_pos = glm::vec3(-3, 0, -3);
-
-  // generate a camera view, based on eye-position and lookAt world-position
-  glm::mat4 view_mat = genView(glm::vec3(2, 2, 20), model_pos);
-
-  glm::vec3 sun_position = glm::vec3(3.0, 10.0, -5.0);
-  glm::vec3 sun_color = glm::vec3(1.0);
-
-  while (!window.Close()) {
-    window.Resize();
-
-    glClearColor(0.2, 0.2, 0.2, 1.0);
-    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-
-    glm::mat4 trans =
-        glm::translate(glm::mat4(1.0f), model_pos);  // reposition model
-    model_rot = glm::rotate(model_rot, glm::radians(0.8f),
-                            glm::vec3(0, 1, 0));  // rotate model on y axis
-    model_mat = trans * model_rot;
-
-    // build a model-view-projection
-    GLint w, h;
-    glfwGetWindowSize(window.window, &w, &h);
-    glm::mat4 mvp = genMVP(view_mat, model_mat, 45.0f, w, h);
-    glUniformMatrix4fv(MVP_u, 1, GL_FALSE, &mvp[0][0]);
-
-    glUniform3fv(sun_position_u, 1, &sun_position[0]);
-    glUniform3fv(sun_color_u, 1, &sun_color[0]);
-
-    drawModel(vao, model);
-    glfwSwapBuffers(window.window);
-    glfwPollEvents();
-  }
-}
-
-static void error_callback(int error, const char *description) {
-  (void)error;
-  fprintf(stderr, "Error: %s\n", description);
-}
-
-int main(int argc, char **argv) {
-  std::string filename = "../../models/Cube/Cube.gltf";
-
-  if (argc > 1) {
-    filename = argv[1];
-  }
-
-  glfwSetErrorCallback(error_callback);
-
-  if (!glfwInit()) return -1;
-
-  // Force create OpenGL 3.3
-  // NOTE(syoyo): Linux + NVIDIA driver segfaults for some reason? commenting out glfwWindowHint will work.
-  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
-  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
-  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
-#ifdef __APPLE__
-  glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
-#endif
-#endif
-
-  Window window = Window(800, 600, "TinyGLTF basic example");
-  glfwMakeContextCurrent(window.window);
-
-#ifdef __APPLE__
-  // https://stackoverflow.com/questions/50192625/openggl-segmentation-fault
-  glewExperimental = GL_TRUE;
-#endif
-
-  glewInit();
-  std::cout << glGetString(GL_RENDERER) << ", " << glGetString(GL_VERSION)
-            << std::endl;
-
-  if (!GLEW_VERSION_3_3) {
-    std::cerr << "OpenGL 3.3 is required to execute this app." << std::endl;
-    return EXIT_FAILURE;
-  }
-
-  glEnable(GL_DEPTH_TEST);
-  glDepthFunc(GL_LESS);
-
-  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
-  glEnable(GL_BLEND);
-
-  displayLoop(window, filename);
-
-  glfwTerminate();
-  return 0;
-}
+#include <fstream>
+#include <iostream>
+
+#include <GL/glew.h>
+#include <GLFW/glfw3.h>
+#include <glm/gtc/matrix_transform.hpp>
+
+#include "shaders.h"
+#include "window.h"
+
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Weverything"
+#endif
+
+// Inlude tinyktx.h before tiny_gltf.h
+// to get TKTX_*** definitions
+#define TINYKTX_IMPLEMENTATION
+#include "../../tinyktx.h"
+
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+
+#define TINYGLTF_IMPLEMENTATION
+#define STB_IMAGE_IMPLEMENTATION
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#define TINYGLTF_NOEXCEPTION
+#define JSON_NOEXCEPTION
+#define TINYGLTF_ENABLE_KTX
+// tinyktx.h is already included above,
+// so let tiny_gltf.h know do not include tinyktx.h anymore
+#define TINYGLTF_NO_INCLUDE_TINY_KTX
+#include "../../tiny_gltf.h"
+
+//#define BUFFER_OFFSET(i) ((char *)nullptr + (i))
+#define BUFFER_OFFSET(i) \
+  (reinterpret_cast<void *>(i))  // TODO(syoyo): Is this right way?
+
+bool loadModel(tinygltf::Model &model, const char *filename) {
+  tinygltf::TinyGLTF loader;
+  std::string err;
+  std::string warn;
+
+  bool res = loader.LoadASCIIFromFile(&model, &err, &warn, filename);
+  if (!warn.empty()) {
+    std::cout << "WARN: " << warn << std::endl;
+  }
+
+  if (!err.empty()) {
+    std::cout << "ERR: " << err << std::endl;
+  }
+
+  if (!res)
+    std::cout << "Failed to load glTF: " << filename << std::endl;
+  else
+    std::cout << "Loaded glTF: " << filename << std::endl;
+
+  return res;
+}
+
+static bool GetOpenGLFormatFromKTX(int ktx_fmt, GLint *internal_format, GLenum *format, GLenum *type) {
+#if defined(TINYGLTF_ENABLE_KTX)
+    bool ret = true;
+
+    std::cout << "fmt = " << ktx_fmt << ", rgb8 fmt = " << TKTX_R8G8B8_UNORM << "\n";
+
+    if (ktx_fmt == TKTX_R8G8B8_UNORM) {
+      (*internal_format) = GL_RGB;
+      (*format) = GL_RGB;
+      (*type) = GL_UNSIGNED_BYTE;
+    } else {
+      // TODO(syoyo): Support more KTX formats.
+      ret = false;
+    }
+
+    return ret;
+#else
+    (void)fmt;
+    (void)internal_format;
+    (void)internal_format;
+    return false;
+#endif
+}
+
+std::map<int, GLuint> bindMesh(std::map<int, GLuint> vbos,
+                               tinygltf::Model &model, tinygltf::Mesh &mesh) {
+  for (size_t i = 0; i < model.bufferViews.size(); ++i) {
+    const tinygltf::BufferView &bufferView = model.bufferViews[i];
+    if (bufferView.target == 0) {  // TODO impl drawarrays
+      std::cout << "WARN: bufferView.target is zero" << std::endl;
+      continue;  // Unsupported bufferView.
+                 /*
+                   From spec2.0 readme:
+                   https://github.com/KhronosGroup/glTF/tree/master/specification/2.0
+                            ... drawArrays function should be used with a count equal to
+                   the count            property of any of the accessors referenced by the
+                   attributes            property            (they are all equal for a
+                   given            primitive).
+                 */
+    }
+
+    tinygltf::Buffer buffer = model.buffers[bufferView.buffer];
+    std::cout << "bufferview.target " << bufferView.target << std::endl;
+
+    GLuint vbo;
+    glGenBuffers(1, &vbo);
+    vbos[i] = vbo;
+    glBindBuffer(bufferView.target, vbo);
+
+    std::cout << "buffer.data.size = " << buffer.data.size()
+              << ", bufferview.byteOffset = " << bufferView.byteOffset
+              << std::endl;
+
+    glBufferData(bufferView.target, bufferView.byteLength,
+                 &buffer.data.at(0) + bufferView.byteOffset, GL_STATIC_DRAW);
+  }
+
+  for (size_t i = 0; i < mesh.primitives.size(); ++i) {
+    tinygltf::Primitive primitive = mesh.primitives[i];
+    tinygltf::Accessor indexAccessor = model.accessors[primitive.indices];
+
+    for (auto &attrib : primitive.attributes) {
+      tinygltf::Accessor accessor = model.accessors[attrib.second];
+      int byteStride =
+          accessor.ByteStride(model.bufferViews[accessor.bufferView]);
+      glBindBuffer(GL_ARRAY_BUFFER, vbos[accessor.bufferView]);
+
+      int size = 1;
+      if (accessor.type != TINYGLTF_TYPE_SCALAR) {
+        size = accessor.type;
+      }
+
+      int vaa = -1;
+      if (attrib.first.compare("POSITION") == 0) vaa = 0;
+      if (attrib.first.compare("NORMAL") == 0) vaa = 1;
+      if (attrib.first.compare("TEXCOORD_0") == 0) vaa = 2;
+      if (vaa > -1) {
+        glEnableVertexAttribArray(vaa);
+        glVertexAttribPointer(vaa, size, accessor.componentType,
+                              accessor.normalized ? GL_TRUE : GL_FALSE,
+                              byteStride, BUFFER_OFFSET(accessor.byteOffset));
+      } else
+        std::cout << "Unsupported vertex attribute: " << attrib.first << std::endl;
+    }
+
+    GLuint texid;
+    glGenTextures(1, &texid);
+
+    tinygltf::Texture &tex = model.textures[0];
+    tinygltf::Image &image = model.images[tex.source];
+
+    glBindTexture(GL_TEXTURE_2D, texid);
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+
+    GLint internal_format = GL_RGBA;
+    GLenum format = GL_RGBA;
+    GLenum type = GL_UNSIGNED_BYTE;
+
+    bool valid = false;
+
+    // KTX extension
+    if (image.extras.Has("ktx_format")) {
+
+      valid = GetOpenGLFormatFromKTX(image.extras.Get("ktx_format").Get<int>(), &internal_format, &format, &type);
+
+      if (valid) {
+
+        std::cout << "ktx_format: " << image.extras.Get("ktx_format").Get<int>() << std::endl;
+        std::cout << "ktx image size: " << image.width << ", " << image.height << std::endl;
+      }
+
+    } else {
+
+      valid = true;
+
+      if (image.component == 1) {
+        format = GL_RED;
+      } else if (image.component == 2) {
+        format = GL_RG;
+      } else if (image.component == 3) {
+        format = GL_RGB;
+      } else if (image.component == 4) {
+        format = GL_RGBA;
+      } else {
+        valid = false;
+      }
+
+      if (image.bits == 8) {
+        type = GL_UNSIGNED_BYTE;
+      } else if (image.bits == 16) {
+        type = GL_UNSIGNED_SHORT;
+      } else {
+        valid = false;
+      }
+
+    }
+
+    if (valid) {
+
+      glTexImage2D(GL_TEXTURE_2D, 0, internal_format, image.width, image.height, 0,
+                   format, type, &image.image.at(0));
+    }
+  }
+
+  return vbos;
+}
+
+// bind models
+void bindModelNodes(std::map<int, GLuint> vbos, tinygltf::Model &model,
+                    tinygltf::Node &node) {
+  bindMesh(vbos, model, model.meshes[node.mesh]);
+  for (size_t i = 0; i < node.children.size(); i++) {
+    bindModelNodes(vbos, model, model.nodes[node.children[i]]);
+  }
+}
+GLuint bindModel(tinygltf::Model &model) {
+  std::map<int, GLuint> vbos;
+  GLuint vao;
+  glGenVertexArrays(1, &vao);
+  glBindVertexArray(vao);
+
+  const tinygltf::Scene &scene = model.scenes[model.defaultScene];
+  for (size_t i = 0; i < scene.nodes.size(); ++i) {
+    bindModelNodes(vbos, model, model.nodes[scene.nodes[i]]);
+  }
+
+  glBindVertexArray(0);
+  // cleanup vbos
+  for (size_t i = 0; i < vbos.size(); ++i) {
+    glDeleteBuffers(1, &vbos[i]);
+  }
+
+  return vao;
+}
+
+void drawMesh(tinygltf::Model &model, tinygltf::Mesh &mesh) {
+  for (size_t i = 0; i < mesh.primitives.size(); ++i) {
+    tinygltf::Primitive primitive = mesh.primitives[i];
+    tinygltf::Accessor indexAccessor = model.accessors[primitive.indices];
+
+    glDrawElements(primitive.mode, indexAccessor.count,
+                   indexAccessor.componentType,
+                   BUFFER_OFFSET(indexAccessor.byteOffset));
+  }
+}
+
+// recursively draw node and children nodes of model
+void drawModelNodes(tinygltf::Model &model, tinygltf::Node &node) {
+  drawMesh(model, model.meshes[node.mesh]);
+  for (size_t i = 0; i < node.children.size(); i++) {
+    drawModelNodes(model, model.nodes[node.children[i]]);
+  }
+}
+void drawModel(GLuint vao, tinygltf::Model &model) {
+  glBindVertexArray(vao);
+
+  const tinygltf::Scene &scene = model.scenes[model.defaultScene];
+  for (size_t i = 0; i < scene.nodes.size(); ++i) {
+    drawModelNodes(model, model.nodes[scene.nodes[i]]);
+  }
+
+  glBindVertexArray(0);
+}
+
+void dbgModel(tinygltf::Model &model) {
+  for (auto &mesh : model.meshes) {
+    std::cout << "mesh : " << mesh.name << std::endl;
+    for (auto &primitive : mesh.primitives) {
+      const tinygltf::Accessor &indexAccessor =
+          model.accessors[primitive.indices];
+
+      std::cout << "indexaccessor: count " << indexAccessor.count << ", type "
+                << indexAccessor.componentType << std::endl;
+
+      tinygltf::Material &mat = model.materials[primitive.material];
+      for (auto &mats : mat.values) {
+        std::cout << "mat : " << mats.first.c_str() << std::endl;
+      }
+
+      for (auto &image : model.images) {
+        std::cout << "image name : " << image.uri << std::endl;
+        std::cout << "  size : " << image.image.size() << std::endl;
+        std::cout << "  w/h : " << image.width << "/" << image.height
+                  << std::endl;
+      }
+
+      std::cout << "indices : " << primitive.indices << std::endl;
+      std::cout << "mode     : "
+                << "(" << primitive.mode << ")" << std::endl;
+
+      for (auto &attrib : primitive.attributes) {
+        std::cout << "attribute : " << attrib.first.c_str() << std::endl;
+      }
+    }
+  }
+}
+
+glm::mat4 genView(glm::vec3 pos, glm::vec3 lookat) {
+  // Camera matrix
+  glm::mat4 view = glm::lookAt(
+      pos,                // Camera in World Space
+      lookat,             // and looks at the origin
+      glm::vec3(0, 1, 0)  // Head is up (set to 0,-1,0 to look upside-down)
+  );
+
+  return view;
+}
+
+glm::mat4 genMVP(glm::mat4 view_mat, glm::mat4 model_mat, float fov, int w,
+                 int h) {
+  glm::mat4 Projection =
+      glm::perspective(glm::radians(fov), (float)w / (float)h, 0.01f, 1000.0f);
+
+  // Or, for an ortho camera :
+  // glm::mat4 Projection = glm::ortho(-10.0f,10.0f,-10.0f,10.0f,0.0f,100.0f);
+  // // In world coordinates
+
+  glm::mat4 mvp = Projection * view_mat * model_mat;
+
+  return mvp;
+}
+
+void displayLoop(Window &window, const std::string &filename) {
+  Shaders shader = Shaders();
+  glUseProgram(shader.pid);
+
+  // grab uniforms to modify
+  GLuint MVP_u = glGetUniformLocation(shader.pid, "MVP");
+  GLuint sun_position_u = glGetUniformLocation(shader.pid, "sun_position");
+  GLuint sun_color_u = glGetUniformLocation(shader.pid, "sun_color");
+
+  tinygltf::Model model;
+  if (!loadModel(model, filename.c_str())) return;
+
+  GLuint vao = bindModel(model);
+  // dbgModel(model); return;
+
+  // Model matrix : an identity matrix (model will be at the origin)
+  glm::mat4 model_mat = glm::mat4(1.0f);
+  glm::mat4 model_rot = glm::mat4(1.0f);
+  glm::vec3 model_pos = glm::vec3(-3, 0, -3);
+
+  // generate a camera view, based on eye-position and lookAt world-position
+  glm::mat4 view_mat = genView(glm::vec3(2, 2, 20), model_pos);
+
+  glm::vec3 sun_position = glm::vec3(3.0, 10.0, -5.0);
+  glm::vec3 sun_color = glm::vec3(1.0);
+
+  while (!window.Close()) {
+    window.Resize();
+
+    glClearColor(0.2, 0.2, 0.2, 1.0);
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    glm::mat4 trans =
+        glm::translate(glm::mat4(1.0f), model_pos);  // reposition model
+    model_rot = glm::rotate(model_rot, glm::radians(0.8f),
+                            glm::vec3(0, 1, 0));  // rotate model on y axis
+    model_mat = trans * model_rot;
+
+    // build a model-view-projection
+    GLint w, h;
+    glfwGetWindowSize(window.window, &w, &h);
+    glm::mat4 mvp = genMVP(view_mat, model_mat, 45.0f, w, h);
+    glUniformMatrix4fv(MVP_u, 1, GL_FALSE, &mvp[0][0]);
+
+    glUniform3fv(sun_position_u, 1, &sun_position[0]);
+    glUniform3fv(sun_color_u, 1, &sun_color[0]);
+
+    drawModel(vao, model);
+    glfwSwapBuffers(window.window);
+    glfwPollEvents();
+  }
+}
+
+static void error_callback(int error, const char *description) {
+  (void)error;
+  fprintf(stderr, "Error: %s\n", description);
+}
+
+static void drop_callback(GLFWwindow *window, int num, const char **paths) {
+  (void)window;
+  printf("dropCB %d\n", num);
+  for (int i = 0; i < num; i++) {
+      printf("%s\n", paths[i]);
+  }
+}
+
+int main(int argc, char **argv) {
+  std::string filename = "../../models/Cube/Cube.gltf";
+
+  if (argc > 1) {
+    filename = argv[1];
+  }
+
+  glfwSetErrorCallback(error_callback);
+
+  if (!glfwInit()) return -1;
+
+    // NOTE(syoyo): For some reason, Linux + NVIDIA driver + apt-installed
+    // glew(1.13) cannot initialize some ARB functions when CONTEXT_VERSION are
+    // explicitly given. Proably we need to compile app with recent glfw and
+    // glew(or use glad) package
+#if !defined(__linux__)
+  // Try to create OpenGL 3.3 context on Windows and macOS
+  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
+  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
+#endif
+
+  // glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
+#ifdef __APPLE__
+  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+  glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
+#endif
+
+  Window window = Window(800, 600, "TinyGLTF basic example");
+
+  glfwSetDropCallback(window.window, drop_callback);
+
+  glfwMakeContextCurrent(window.window);
+
+#ifdef __APPLE__
+  // https://stackoverflow.com/questions/50192625/openggl-segmentation-fault
+  glewExperimental = GL_TRUE;
+#endif
+
+  if (glewInit() != GLEW_OK) {
+    std::cerr << "Failed to initialie glew." << std::endl;
+    return EXIT_FAILURE;
+  }
+
+  std::cout << glGetString(GL_RENDERER) << ", " << glGetString(GL_VERSION)
+            << std::endl;
+
+  if (!GLEW_ARB_vertex_array_object) {
+    std::cerr << "GLEW_ARB_vertex_array_object was not available." << std::endl;
+    return EXIT_FAILURE;
+  }
+
+  if (!GLEW_VERSION_3_3) {
+    std::cerr << "OpenGL 3.3 is required to execute this app." << std::endl;
+    return EXIT_FAILURE;
+  }
+
+  glEnable(GL_DEPTH_TEST);
+  glDepthFunc(GL_LESS);
+
+  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+  glEnable(GL_BLEND);
+
+  displayLoop(window, filename);
+
+  glfwTerminate();
+  return 0;
+}

models/Cube-KTX/Cube.gltf

@@ -0,0 +1,193 @@
+{
+   "accessors" : [
+      {
+         "bufferView" : 0,
+         "byteOffset" : 0,
+         "componentType" : 5123,
+         "count" : 36,
+         "max" : [
+            35
+         ],
+         "min" : [
+            0
+         ],
+         "type" : "SCALAR"
+      },
+      {
+         "bufferView" : 1,
+         "byteOffset" : 0,
+         "componentType" : 5126,
+         "count" : 36,
+         "max" : [
+            1.000000,
+            1.000000,
+            1.000001
+         ],
+         "min" : [
+            -1.000000,
+            -1.000000,
+            -1.000000
+         ],
+         "type" : "VEC3"
+      },
+      {
+         "bufferView" : 2,
+         "byteOffset" : 0,
+         "componentType" : 5126,
+         "count" : 36,
+         "max" : [
+            1.000000,
+            1.000000,
+            1.000000
+         ],
+         "min" : [
+            -1.000000,
+            -1.000000,
+            -1.000000
+         ],
+         "type" : "VEC3"
+      },
+      {
+         "bufferView" : 3,
+         "byteOffset" : 0,
+         "componentType" : 5126,
+         "count" : 36,
+         "max" : [
+            1.000000,
+            -0.000000,
+            -0.000000,
+            1.000000
+         ],
+         "min" : [
+            0.000000,
+            -0.000000,
+            -1.000000,
+            -1.000000
+         ],
+         "type" : "VEC4"
+      },
+      {
+         "bufferView" : 4,
+         "byteOffset" : 0,
+         "componentType" : 5126,
+         "count" : 36,
+         "max" : [
+            1.000000,
+            1.000000
+         ],
+         "min" : [
+            -1.000000,
+            -1.000000
+         ],
+         "type" : "VEC2"
+      }
+   ],
+   "asset" : {
+      "generator" : "VKTS glTF 2.0 exporter",
+      "version" : "2.0"
+   },
+   "bufferViews" : [
+      {
+         "buffer" : 0,
+         "byteLength" : 72,
+         "byteOffset" : 0,
+         "target" : 34963
+      },
+      {
+         "buffer" : 0,
+         "byteLength" : 432,
+         "byteOffset" : 72,
+         "target" : 34962
+      },
+      {
+         "buffer" : 0,
+         "byteLength" : 432,
+         "byteOffset" : 504,
+         "target" : 34962
+      },
+      {
+         "buffer" : 0,
+         "byteLength" : 576,
+         "byteOffset" : 936,
+         "target" : 34962
+      },
+      {
+         "buffer" : 0,
+         "byteLength" : 288,
+         "byteOffset" : 1512,
+         "target" : 34962
+      }
+   ],
+   "buffers" : [
+      {
+         "byteLength" : 1800,
+         "uri" : "Cube.bin"
+      }
+   ],
+   "images" : [
+      {
+         "uri" : "Cube_BaseColor.ktx"
+      },
+      {
+         "uri" : "Cube_MetallicRoughness.ktx"
+      }
+   ],
+   "materials" : [
+      {
+         "name" : "Cube",
+         "pbrMetallicRoughness" : {
+            "baseColorTexture" : {
+               "index" : 0
+            },
+            "metallicRoughnessTexture" : {
+               "index" : 1
+            }
+         }
+      }
+   ],
+   "meshes" : [
+      {
+         "name" : "Cube",
+         "primitives" : [
+            {
+               "attributes" : {
+                  "NORMAL" : 2,
+                  "POSITION" : 1,
+                  "TANGENT" : 3,
+                  "TEXCOORD_0" : 4
+               },
+               "indices" : 0,
+               "material" : 0,
+               "mode" : 4
+            }
+         ]
+      }
+   ],
+   "nodes" : [
+      {
+         "mesh" : 0,
+         "name" : "Cube"
+      }
+   ],
+   "samplers" : [
+      {}
+   ],
+   "scene" : 0,
+   "scenes" : [
+      {
+         "nodes" : [
+            0
+         ]
+      }
+   ],
+   "textures" : [
+      {
+         "sampler" : 0,
+         "source" : 0
+      },
+      {
+         "sampler" : 0,
+         "source" : 1
+      }
+   ]
+}

models/Cube-KTX/README.md

@@ -0,0 +1,12 @@
+License: Donated by Norbert Nopper for glTF testing.
+
+https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/Cube
+
+
+----
+
+Converted .png to .ktx image by Syoyo Fujita.
+
+.png -> .ppm using image magic(resize with 25% to reduce file size)
+.ppm -> .ktx using `toktx` in KTX-Software https://github.com/KhronosGroup/KTX-Software
+

tiny_gltf.h

@@ -492,14 +492,19 @@ struct Image {
   std::string name;
   int width;
   int height;
-  int component;
+
+  //
+  // For KTX image, component, bits and pixel_type will be set to `0`, and KTX attributes are stored in `extras`.
+  // FIXME(syoyo): Find more proper way to handle KTX and non-KTX image by keeping backward-compatibility as much as possible.
+  //
+  int component;   // The number of channel components in the image.
   int bits;        // bit depth per channel. 8(byte), 16 or 32.
   int pixel_type;  // pixel type(TINYGLTF_COMPONENT_TYPE_***). usually
                    // UBYTE(bits = 8) or USHORT(bits = 16)
   std::vector<unsigned char> image;
   int bufferView;        // (required if no uri)
   std::string mimeType;  // (required if no uri) ["image/jpeg", "image/png",
-                         // "image/bmp", "image/gif"]
+                         // "image/bmp", "image/gif", etc]
   std::string uri;       // (required if no mimeType)
   Value extras;
   ExtensionMap extensions;
@@ -1124,6 +1129,12 @@ class TinyGLTF {
 #include "draco/core/decoder_buffer.h"
 #endif
 
+#ifdef TINYGLTF_ENABLE_KTX
+#ifndef TINYGLTF_NO_INCLUDE_TINY_KTX
+#include "tiny_ktx.h"
+#endif
+#endif
+
 #ifndef TINYGLTF_NO_STB_IMAGE
 #ifndef TINYGLTF_NO_INCLUDE_STB_IMAGE
 #include "stb_image.h"
@@ -1679,8 +1690,8 @@ void TinyGLTF::SetImageLoader(LoadImageDataFunction func, void *user_data) {
   load_image_user_data_ = user_data;
 }
 
-#ifndef TINYGLTF_NO_STB_IMAGE
-bool LoadImageData(Image *image, const int image_idx, std::string *err,
+#if !defined(TINYGLTF_NO_STB_IMAGE)
+bool LoadImageDataSTB(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) {
   (void)user_data;
@@ -1777,6 +1788,232 @@ bool LoadImageData(Image *image, const int image_idx, std::string *err,
 }
 #endif
 
+#if defined(TINYGLTF_ENABLE_KTX)
+
+struct SimpleVFile {
+  std::string *err = nullptr;
+  const uint8_t *data = nullptr;
+  size_t pos = 0;
+  size_t len = 0;
+};
+
+static void tinyktxCallbackError(void *user, char const *msg) {
+  SimpleVFile *ss = reinterpret_cast<SimpleVFile *>(user);
+
+  if (ss->err) {
+    (*ss->err) += "Tiny_Ktx ERROR: " + std::string(msg) + "\n";
+  }
+}
+
+
+static void *tinyktxCallbackAlloc(void *user, size_t size) {
+  (void)user;
+  //std::cerr << "Alloc : " << std::to_string(size) << "\n";
+  return malloc(size);
+};
+
+static void tinyktxCallbackFree(void *user, void *data) {
+  (void)user;
+  free(data);
+};
+
+static size_t tinyktxCallbackRead(void *user, void* data, size_t size) {
+  SimpleVFile *ss = reinterpret_cast<SimpleVFile *>(user);
+
+  if ((ss->pos + size) > ss->len) {
+    if (ss->err) {
+      std::stringstream msg;
+      msg << "KTX read: Invalid data length. pos = " << ss->pos << ", len = " << ss->len << ", requested size to read = " << size << "\n";
+      (*ss->err) += msg.str();
+    }
+    return size_t(0);
+  }
+
+  memcpy(data, ss->data + ss->pos, size);
+
+  // Advance pos
+  ss->pos += size;
+
+  return size;
+};
+
+static bool tinyktxCallbackSeek(void *user, int64_t offset) {
+
+  SimpleVFile *ss = reinterpret_cast<SimpleVFile *>(user);
+
+  if ((offset < 0) || (size_t(offset) >= ss->len)) {
+    if (ss->err) {
+      std::stringstream msg;
+      msg << "KTX read: Invalid data offset. len = " << ss->len << ", requested offset = " << offset << "\n";
+      (*ss->err) += msg.str();
+    }
+
+    return false;
+  }
+
+  ss->pos = offset;
+  return true;
+
+}
+
+static int64_t tinyktxCallbackTell(void *user) {
+  SimpleVFile *ss = reinterpret_cast<SimpleVFile *>(user);
+
+  return int64_t(ss->pos);
+};
+
+
+bool LoadImageDataKTX(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) {
+  (void)user_data;
+  (void)warn;
+  (void)req_width;
+  (void)req_height;
+
+  TinyKtx_Callbacks callbacks {
+                  &tinyktxCallbackError,
+                  &tinyktxCallbackAlloc,
+                  &tinyktxCallbackFree,
+                  &tinyktxCallbackRead,
+                  &tinyktxCallbackSeek,
+                  &tinyktxCallbackTell
+  };
+
+  SimpleVFile vfile;
+  vfile.err = err;
+  vfile.pos = 0;
+  vfile.data = bytes;
+  vfile.len = size;
+
+  auto ctx =  TinyKtx_CreateContext( &callbacks, reinterpret_cast<void *>(&vfile) );
+  TinyKtx_ReadHeader(ctx);
+  uint32_t w = TinyKtx_Width(ctx);
+  uint32_t h = TinyKtx_Height(ctx);
+  uint32_t d = TinyKtx_Depth(ctx);
+
+  TinyKtx_Format fmt = TinyKtx_GetFormat(ctx);
+
+  if(fmt == TKTX_UNDEFINED) {
+      TinyKtx_DestroyContext(ctx);
+      return false;
+  }
+
+  int num_mipmaps = TinyKtx_NumberOfMipmaps(ctx);
+  if (num_mipmaps < 1) {
+    // ???
+    if (err) {
+      (*err) += "Number of mipmaps are zero for KTX image[" + std::to_string(image_idx) + ".\n";
+    }
+    TinyKtx_DestroyContext(ctx);
+    return false;
+  }
+
+  {
+    // TODO(syoyo): Support mipmap.
+    int miplevel = 0;
+
+    size_t byte_count = TinyKtx_ImageSize(ctx, miplevel);
+    if (byte_count == 0) {
+      // ???
+      if (err) {
+        (*err) += "KTX image [" + std::to_string(image_idx) + "] has zero bytes.\n";
+      }
+
+      TinyKtx_DestroyContext(ctx);
+      return false;
+    }
+
+    const void *src_ptr = TinyKtx_ImageRawData(ctx, miplevel);
+    if (src_ptr == nullptr) {
+      TinyKtx_DestroyContext(ctx);
+      return false;
+    }
+
+    image->image.resize(byte_count);
+    memcpy(image->image.data(), TinyKtx_ImageRawData(ctx, miplevel), byte_count);
+
+    TinyKtx_DestroyContext(ctx);
+
+    // Set to 0 for KTX image.
+    image->pixel_type = 0;
+    image->bits = 0;
+    image->component = 0;
+
+    // extras for KTX
+    Value::Object extras;
+    extras["ktx_format"] = Value(int(fmt)); // TODO(syoyo): Store OpenGL format
+    extras["depth"] = Value(int(d));
+    extras["byteCount"] = Value(int(byte_count)); // Assume image size is < 2GB
+    image->extras = Value(extras);
+    // TODO(syoyo): Store more KTX attributes.
+  }
+
+  image->width = w;
+  image->height = h;
+
+  return true;
+}
+#endif
+
+bool LoadImageData(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) {
+
+  bool ret = false;
+
+  std::string stb_err;
+  std::string stb_warn;
+
+#if !defined(TINYGLTF_NO_STB_IMAGE)
+  // Try to load images using stb_image(png, gif, bmp, tga, ...)
+
+  ret = tinygltf::LoadImageDataSTB(image, image_idx, &stb_err, &stb_warn, req_width, req_height,
+                   bytes, size, user_data);
+
+  if (ret) {
+    return true;
+  }
+
+#endif
+
+  std::string ktx_err;
+  std::string ktx_warn;
+
+#if defined(TINYGLTF_ENABLE_KTX)
+  // Try KTX image
+
+  ret = tinygltf::LoadImageDataKTX(image, image_idx, &ktx_err, &ktx_warn, req_width, req_height,
+                   bytes, size, user_data);
+
+  if (ret) {
+    if (warn) {
+      (*warn) = ktx_warn;
+    }
+    return true;
+  }
+
+#endif
+
+  if (err) {
+    (*err) = stb_err + ktx_err;
+  }
+
+  if (warn) {
+    (*warn) = stb_warn + ktx_warn;
+  }
+
+  (void)image;
+  (void)image_idx;
+  (void)req_width;
+  (void)req_height;
+  (void)bytes;
+  (void)size;
+  (void)user_data;
+
+  return false;
+}
+
 void TinyGLTF::SetImageWriter(WriteImageDataFunction func, void *user_data) {
   WriteImageData = func;
   write_image_user_data_ = user_data;
@@ -1800,6 +2037,8 @@ bool WriteImageData(const std::string *basepath, const std::string *filename,
   std::string header;
   std::vector<unsigned char> data;
 
+  // TODO(LTE): Support ktx
+
   if (ext == "png") {
     if ((image->bits != 8) ||
         (image->pixel_type != TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE)) {
@@ -2047,6 +2286,10 @@ static std::string MimeToExt(const std::string &mimeType) {
     return "bmp";
   } else if (mimeType == "image/gif") {
     return "gif";
+#if defined(TINYGLTF_ENABLE_KTX)
+  } else if (mimeType == "image/ktx") {
+    return "ktx";
+#endif
   }
 
   return "";
@@ -2107,6 +2350,13 @@ bool IsDataURI(const std::string &in) {
     return true;
   }
 
+#if defined(TINYGLTF_ENABLE_KTX)
+  header = "data:image/ktx;base64,";
+  if (in.find(header) == 0) {
+    return true;
+  }
+#endif
+
   header = "data:text/plain;base64,";
   if (in.find(header) == 0) {
     return true;
@@ -2160,6 +2410,16 @@ bool DecodeDataURI(std::vector<unsigned char> *out, std::string &mime_type,
     }
   }
 
+#if defined(TINYGLTF_ENABLE_KTX)
+  if (data.empty()) {
+    header = "data:image/ktx;base64,";
+    if (in.find(header) == 0) {
+      mime_type = "image/ktx";
+      data = base64_decode(in.substr(header.size()));  // cut mime string.
+    }
+  }
+#endif
+
   if (data.empty()) {
     header = "data:text/plain;base64,";
     if (in.find(header) == 0) {