Unity 2021 Shaders and Effects Cookbook - Fourth Edition

Chapter 6: Physically Based Rendering

Introduced in Unity 5, physically based rendering or PBR is a shading model that seeks to render graphics in a way that acts similarly to how light works in the real world. All the lighting models we encountered in Chapter 5, Understanding Lighting Models, were very primitive descriptions of how light behaves. The most important aspect while creating them was efficiency. Real-time shading is expensive, and techniques such as Lambertian or Blinn-Phong are a compromise between computational cost and realism.

Having a more powerful GPU has allowed us to write progressively more sophisticated lighting models and rendering engines to simulate how light behaves. This is, in a nutshell, the philosophy behind PBR. ...