3: OpenGL 1.1- Geometry
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It is time to move on to computer graphics in three dimensions, although it won’t be until Section 2 of this chapter that we really get into 3D. You will find that many concepts from 2D graphics carry over to 3D, but the move into the third dimension brings with it some new features that take a while to get used to.
Our focus will be OpenGL, a graphics API that was introduced in 1992 and has gone through many versions and many changes since then. OpenGL is a low-level graphics API, similar to the 2D APIs we have covered. It is even more primitive in some ways, but of course it is complicated by the fact that it supports 3D.
For the next two chapters, the discussion is limited to OpenGL 1.1. OpenGL 1.1 is a large API, and we will only cover a part of it. The goal is to introduce 3D graphics concepts, not to fully cover the API. A significant part of what we cover here has been removed from the most modern versions of OpenGL. However, modern OpenGL in its pure form has a very steep initial learning curve, and it is really not a good starting place for someone who is encountering 3D graphics for the first time. Some additional support is needed—if not OpenGL 1.1 then some similar framework. Since OpenGL 1.1 is still supported, at least by all desktop implementations of OpenGL, it’s a reasonable place to start.
This chapter concentrates on the geometric aspects of 3D graphics, such as defining and transforming objects and projecting 3D scenes into 2D images. The images that we produce will look very unrealistic. In the next chapter, we will see how to add some realism by simulating the effects of lighting and of the material properties of surfaces.