Graphics Programs Reference
In-Depth Information
Figure 22-6:
Entering 3D coordinates to draw a 3D polyline.
Creating 2D representations in this way is straightforward, though tedious for all but the
simplest objects. More important, a wireframe model becomes increasingly difficult to
decipher as the complexity of the model increases. You see a mass of lines representing
the edges, and you have difficulty telling which parts of which edges are in front of oth-
ers. To reduce this visual confusion, you need to graduate to surface or solid modeling
commands. I introduce you to solid modeling in subsequent sections of this chapter.
Gaining a solid foundation
Solid modeling is in many ways the culmination of 3D CAD. Solids more accurately rep-
resent most real-world objects than do wireframes or surfaces. And even when repres-
entational accuracy isn't the main issue, it's easier to construct many kinds of models
with solids.
Many special-purpose solid modeling programs use a combination of solid
and surface modeling techniques for maximum flexibility in constructing and edit-
ing 3D models. These kinds of programs — and solid modeling in general — are
becoming especially popular in mechanical design.
Constructing the basic building blocks — or solid primitives — for a solid model in
AutoCAD isn't difficult. Just follow these steps:
