Introduction

All the lighting models encountered in Chapter 3, Understanding Lighting Models, were very primitive descriptions of how light behaves. The most important aspect during their making was efficiency. Real-time shading is expensive, and techniques such as Lambertian or BlinnPhong are a compromise between computational cost and realism. Having a more powerful graphics processing unit (GPU) has allowed us to write progressively more sophisticated lighting models and rendering engines, with the aim of simulating how light actually behaves. This is, in a nutshell, the philosophy behind PBR. As the name suggests, it tries to get as close as possible to the physics behind the processes that give a unique look to each material. Despite this, the term PBR has been widely used in marketing campaigns and is more of a synonym for state-of-the-art rendering rather than a well-defined technique. Unity 5 implements PBR by introducing two important changes. The first is a completely new lighting...