OpenGL-Registry VS ImGuizmo

OpenGL

The OpenGL bindings in particular are, I believe, automatically generated from the OpenGL Registry, a machine-readable specification of the entire OpenGL API. That exists because OpenGL is a specification with a lot of implementations from different vendors.

You can find them in glext.h which is put out by Khronos on the official OpenGL-Registry github page. It's probably available elsewhere too but the official online OpenGL docs are kind of a zoo so I probably wouldn't waste too much time looking for them there.

These header files are generated mechanically from XML files maintained here: https://github.com/KhronosGroup/OpenGL-Registry/tree/master/xml

If you're also using Dear ImGui then you can take a look at ImGuizmo (https://github.com/CedricGuillemet/ImGuizmo) Quite a nice library for this, works as an ImGui overlay so its very easy to integrate.

Although it's odd that the white circle is round and the others are not. I think it's a bug in ImGuizmo because I just tested it and the other Dear ImGui windows and widgets stay at the correct aspect ratio, so it's probably some value that's not being read correctly. Maybe open an issue on Github to let the autor know?

...but if you really want to do it yourself here's an example where they do that. If you want everything it winds up being pretty long.

You mention "Since no proper box-editing tool seems to exist, I had to write my own" in the blog; you might be interested to check out ImGuizmo based on Dear ImGui. Your own solution looks pretty decent though.