Chapter 8 - OpenGL implementations

Abstract

This chapter describes some of the ways in which OpenGL has evolved and is currently evolving and also discusses some interesting aspects of implementing the hardware acceleration of the OpenGL pipeline. To accommodate the rapid innovation in the field of computer graphics, the OpenGL design also allows an implementation to support additional features. Each feature is packaged as a mini-specification that adds new commands, tokens, and state of the pipeline. These extensions server two purposes: (1) they allow new features to be “field tested,” and (2) if they prove successful they are incorporated into a later version of the specification. Looking at the features added to the new versions, the most significant changes in OpenGL have occurred in the way data is managed and moved in and out of the pipeline and also in the major improvement in the capabilities of the texture-mapping subsystem. The first class of changes reflects a better understanding of the way applications manage data and an evolving strategy to tune the data transfer model to various hardware technologies. The class of changes reflects the desire for more advanced fragment shading capabilities.