Use rapidjson as a JSON library

[syoyo]

Currently TinyGLTF uses nlohmann's json.hpp https://github.com/nlohmann/json as an underlying JSON library.

json.hpp is working well, but is overkill for TinyGLTF and sometimes it faces the portability problem related to C++ compiler versions.

https://github.com/dropbox/json11 is much more simple, portable, and has enough feature for TinyGLTF. I have implemented json11 version of TinyGLTF in json11 branch: https://github.com/syoyo/tinygltf/tree/json11

I am planning to switch to use json11 after running several tests.

[meshula]

You might want to check timings. nlohmann json is not that fast, but it's faster than dropbox/json11...

https://github.com/miloyip/nativejson-benchmark

I'm personally using rapidjson, but YMMV of course.

[syoyo]

I'm personally using rapidjson, but YMMV of course.

You can contribute rapidjson version of TinyGLTF. PR is always welcome!
(Selecting JSON library by ifdef would be nice)

[vinjn]

Love this change - json.hpp is too huge

[Ybalrid]

I tend to agree about RapidJSON being a great choice

[syoyo]

I have revisiting rapidjson and found there is a script which can generate single file of rapidjson headers.

Tencent/rapidjson#863

I have wrote rapidjson-amalgamation version of tinygltf(W.I.P.) and it works well so far.

https://github.com/syoyo/tinygltf/tree/rapidjson

It looks promising so I am planning to switch to use rapidjson for faster C++ compilation and builtin support of schema validator.

[Selmar]

This will be great for us as well, as we are currently struggling with the # of allocations. Schema validation is an awesome plus! 👍

[syoyo]

We can now use RapidJSON in master branch by defining TINYGLTF_USE_RAPIDJSON and set include path to RapidJSON.