Stylized GGX Shading: How to Get Toon Highlights with PBR

This article presents a method for achieving stylized, toon-like specular highlights while retaining the benefits of physically based rendering. By modifying the GGX Trowbridge-Reitz normal distribution function with a 'Specular Size' parameter, highlights can be expanded at low roughness while preserving soft gradients at high roughness. An improved version uses a 'GGXMatching' parameter to better match the original GGX shape for rough materials. The author shares insights from game development, including additional techniques like reduced SH coefficients and rim lighting.