CG Basics - An Introduction to Computer Graphics for Artists - page 20

Fig. 2.14 Two cubes rendered in opaque and semi-transparent shaded mode

Now turn shading on. With shading on, you will see your cube as a solid
object, as lit by a default light. This light is attached to your camera so that it is
always pointed at the object you are looking at. If it were not attached to the
camera, your object would be diffi cult or impossible to see from some views.
There are reasons to work in all three of the display modes described so far:
wireframe, backface culling, and shaded mode, so most modelers will use them
all while working on a project, even if they prefer one for most purposes. There
is another viewing mode that is a hybrid of the other modes. It is a ghost or x-ray
mode that allows you to see through a semi-transparent shaded object with a non-
occluded wireframe display. This is helpful when you need to see the back of
your object, but you need the semi-transparent shaded display to help orient the
object in space (Fig. 2.14 ).
There are other display options, and it is worth your while to go through them.
You can turn display of different elements on or off (like lights, vertices, curves,
patches, cameras, etc.). It is a long list, and you can have some fun exploring it
yourself. In practice, you will not use most of the tools in any CG application,
depending on your specialty, but it isn't a bad idea to know what is inside your tool
chest. See Table 2.4 for a list of the most common draw modes.

2.4 Geometry

Computer Graphics uses a number of mathematical terms to describe the various
elements used in 3D applications. Many of the terms are recognizable from the
study of Geometry. Among CG artists, the word Geometry is used to refer to 3D
models. The model is where most fi les begin, and to understand it a little better, its
elements should be defi ned. The parts of a model are called either elements or
components .