Deferred Shading Tutorial Fabio Policarpo1 Francisco Fonseca2
[email protected] [email protected] CheckMate Games1,2 Pontifical Catholic University of Rio de Janeiro2 ICAD/Igames/VisionLab 1. Introduction Techniques usually consider non-interactive a few years ago are now possible in real-time using the flexibility and speed of new programmable graphics hardware. An example of that is the deferred shading technique, which is an approach that postpones shading calculations for a fragment1 until the visibility of that fragment is completely determined. In other words, it implies that only fragments that really contribute to the resultant image are shaded. Although deferred shading has become practical for real-time applications in recent years, this technique was firstly published in 1988 by Michael Deering et al. [Deering88]. In that work, the authors proposed a VLSI system where a pipeline of triangle processors rasterizes the geometry, and then a pipeline of shading processors applies Phong shading [Phong75] with multiple light sources to such geometry. After the initial research performed by Deering et al., the next relevant work involving deferred shading was developed by Saito and Takahashi [Saito90] in 1990. The authors of this article proposed a rendering technique that produces 3D images that favor the recognition of shapes and patterns, since shapes can be readily understood if certain geometric properties are enhanced. In order to optimize the enhancement process, geometric properties of the surfaces are preserved as Geometric-Buffers (G-buffers). So, by using G-buffers as intermediate results, artificial enhancement processes are separated from geometric processes (projection and hidden surface removal) and physical processes (shading and texture mapping), and performed as a post-processing pass.