acorn PBR renderer and game engine Latest Screenshot References Karis, Real Shading in Unreal Engine 4, 2013 Neubelt, Pettineo, Crafting a Next-Gen Material Pipeline for The Order: 1886, 2013 Lagarde, Moving Frostbite to PBR, 2014 Elek, Rendering Parameterizable Planetary Atmospheres with Multiple Scattering in Real-Time, 2009 Hillaire, Physically Based Sky, Atmosphere and Cloud Rendering in Frostbite, 2016