QtWS16- Qt 3D and Physics Based Rendering, Sean Harmer, KDAB
Day 2 at QtWS16, Sean Harmer, KDAB "Qt 3D and Physics Based Rendering"
Physics Based Rendering (PBR) is the latest and greatest trend in real-time rendering yielding much more visually believable images than the traditional Phong or ad-hoc lighting models. The underlying concept is that the shaders should use physical principles in the encoded models – chief of which are conservation of energy and the Fresnel effect. PBR is used in many AAA game titles but here we will show how to make use of it with Qt 3D as it is widely applicable to many other types of 3D content such as for use within engineering and visualization. In this talk we will cover how to go take your raw 3D meshes, look at how to prepare textures suitable for use with a PBR-based workflow and how to feed these into a Qt 3D application. Along the way, we will explain how Physics Based Rendering works and how its formulation helps convince the brain of its realism without destroying performance. We will also take a look at some techniques that are often used in conjunction with PBR such as ambient occlusion and parallax mapping. Physics Based Rendering is a family of techniques for simulating how light interacts with surfaces. It can be applied in both offline renderers such as path tracers used in the production of television and film VFX, and more importantly for us, in real time rendering systems such as Qt 3D. There are two main groups of PBR techniques that fall under the Metal-Roughness and Specular-Glossiness workflows. This talk will concentrate on the Metal-Roughness workflow. We will show all the tooling required to take simple 3D meshes, uv-unwrap and export them for use in specialized texturing tools that can then be used to generate the images needed to feed into PBR GLSL shaders. In addition to the material textures, we will also show how to process HDR environment maps to allow high quality specular reflections to be calculated in real time. The talk will explain how all of these assets work together to produce convincing results. We will also provide tips on reducing the overall memory usage by using modern GPU facilities for managing textures.