If you are familiar with Unity 4, you may know that the default shader it provided was based on a lighting model called Lambertian reflectance. This recipe will show you how it is possible to create a shader with a custom lighting model and explains the mathematics involved and implementation. The following diagram shows the same geometry rendered with a Standard Shader (right) and a diffuse Lambert one (left):
Shaders based on Lambertian reflectance are classified as non-photorealistic; no object in the real world really looks like this. However, Lambert Shaders are still often used in low-poly games ...
