Real-Time Shading
Written for video game developers, scientists and engineers dealing with graphic models, and graphics professionals, this book covers real-time shading systems, their design and how they work.
TABLE OF CONTENTS Real-Time Shading
Chapter 9: Classifying Shaders
Any graphics system can be braodly classified as using high- or low- level shading We can further classify the shading capability of any system (real-time or not) into four broad categories. For the purposes of this book, we ll call these four fixed-function shading, parameterized shading, programmable shading and procedural shading.
9.1 Fixed-Function Shading
Fixed-function shading is the lowest-level, most restrictive of the four categories. It is also the style of shading that first appeared on graphics hardware and was prevalent for decades. It provides a single fixed-function to determine the color of rendered objects. This function can be something simple, like interpolate the colors given at each triangle vertex , or something more complicated, like combine this texture with these diffuse and specular lighting terms . Fixed-function shading is good enough for quite a few tasks, but anything not included in the one fixed function cannot be done. A fixed-function shading model is not designed to do different things, beyond a little tweaking. It is designed to do one thing, period.
9.2 Parameterized Shading
Parameterized shading goes slightly beyond single-function fixed shading models. It is still based on one (or a choice of several) fixed shading functions, but much more flexible ones. The distinguishing feature of a parameterized shader is a model complex and flexible enough that its users can create effects that were never directly envisioned by the designers. It is a shading model designed from the ground up to be tweaked and repurposed.
Figure 9.1: Left: A...
Copyright A K Peters, Ltd. 2002 under license agreement with Books24x7
