Implementing the glTF 2.0 specular-glossiness shading model
The specular-glossiness extension is a deprecated and archived in the official Khronos repository. However, we will demonstrate how to use it, as it remains available in many existing 3D assets. In the next chapter, we will introduce a new glTF specular extension, KHR_materials_specular, that replaces this older specular-glossiness shading model and show how to convert from the old model to the new extension. Originally, the specular-glossiness model was added to glTF PBR as an extension to support an artist-driven approach. For example, game development often requires greater flexibility in controlling specular effects, and the ability to adjust glossiness is essential in such scenarios.
Over time, more advanced glTF PBR extensions were introduced, making the original specular-glossiness model obsolete. To provide similar functionality within the standard metallic-roughness workflow, a new specular extension was developed...
