Add single file version of lodepng.

LICENSE.lodepng

@@ -0,0 +1,21 @@
+Copyright (c) 2005-2018 Lode Vandevenne
+
+This software is provided 'as-is', without any express or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+    1. The origin of this software must not be misrepresented; you must not
+    claim that you wrote the original software. If you use this software
+    in a product, an acknowledgment in the product documentation would be
+    appreciated but is not required.
+
+    2. Altered source versions must be plainly marked as such, and must not be
+    misrepresented as being the original software.
+
+    3. This notice may not be removed or altered from any source
+    distribution.
+    

README.md

@@ -82,6 +82,7 @@ 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)
+* lodepng : Copyright (c) 2005-2018 Lode Vandevenne. zlib license. https://lodev.org/lodepng/
 
 
 ## Build and example
@@ -128,6 +129,7 @@ if (!ret) {
 * `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.
 * `TINYGLTF_NO_EXTERNAL_IMAGE` : Do not try to load external image file. This option woulde be helpful if you do not want load image file during glTF parsing.
+* `TINYGLTF_NO_LODEPNG` : Do not load 16bit PNG image with lodepng. Instead use `TinyGLTF::SetImageLoader(LoadimageDataFunction LoadImageData, void *user_data)` to set a callback for loading images(You'll also need to disable stb image with `TINYGLTF_NO_STB_IMAGE`).
 
 ### Saving gltTF 2.0 model
 * [ ] Buffers.
@@ -169,4 +171,5 @@ $ ./tester_noexcept
 
 * 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.
+* lodepng : zlib license
 * catch : Copyright (c) 2012 Two Blue Cubes Ltd. All rights reserved. Distributed under the Boost Software License, Version 1.0.

loader_example.cc

@@ -4,6 +4,7 @@
 #define TINYGLTF_IMPLEMENTATION
 #define STB_IMAGE_IMPLEMENTATION
 #define STB_IMAGE_WRITE_IMPLEMENTATION
+#define LODEPNG_IMPLEMENTATION
 #include "tiny_gltf.h"
 
 #include <cstdio>

tiny_gltf.h

@@ -34,6 +34,7 @@
 //  - jsonhpp: C++ JSON library.
 //  - base64: base64 decode/encode library.
 //  - stb_image: Image loading library.
+//  - lodepng: Load 16bit PNG.
 //
 #ifndef TINY_GLTF_H_
 #define TINY_GLTF_H_
@@ -1058,6 +1059,10 @@ class TinyGLTF {
 #include "./stb_image_write.h"
 #endif
 
+#ifndef TINYGLTF_NO_LODEPNG
+#include "./lodepng.h"
+#endif
+
 #ifdef __clang__
 #pragma clang diagnostic pop
 #endif
@@ -2460,6 +2465,7 @@ static bool ParseImage(Image *image, std::string *err, std::string *warn,
     // Keep texture path (for textures that cannot be decoded)
     image->uri = uri;
 #ifdef TINYGLTF_NO_EXTERNAL_IMAGE
+    // TODO(syoyo): Call LoadImageData callback?
     return true;
 #endif
     if (!LoadExternalFile(&img, err, warn, uri, basedir, false, 0, false, fs)) {