Description:

libgltf is a C++ library for rendering OpenGL models stored in glTF
format.

The glTF, the GL Transmission Format, is the runtime asset format for
the GL APIs: WebGL, OpenGL ES, and OpenGL. glTF bridges the gap
between formats used by modeling tools and the GL APIs. You can read
more about the format in it's specification:
https://github.com/KhronosGroup/glTF/blob/schema/specification/README.md

libgltf provides methods to load the OpenGL scene from glTF format and
render it into an existing OpenGL context. libgltf also allows to
change the camera position so the scene can be displayed from
different points of view.

Summary, libgltf can be a good base of a glTF viewer.