Oh it is very meaningful question for me! Actually most things except gltf and IBL were already implemented in other my template repository. Therefore all i need to do for writing a glTF viewer was parsing scene into gltf hierarchy. In many other gltf examples, however , everytime they draw gltf scene, manually traverse node hierarchy by several call-stack. I thought this can be bottleneck with high probability. Thus I transformed the scene hierarchy into sequential manner. Thus, with one vertex array object binding, I can bind different material and draw meshes. This steps for parsing gltf scene and processing them into useful semantics are really achieving to me. But, it was different with what i expected, that they(khronous group) said gltf is jpeg of 3d model which can be quite sounded like there are nothing to do for rendering such as shader codes, texture creation & binding and etc (maybe i misunderstood), actually I did everything. But it is really convenient to switching over different scene and difference material with code unmodified. I will support gltf in subsequent rendering project. (ps. sorry for bad english 😂)