Graphics Programs Reference
In-Depth Information
U sing Face Loops
As mentioned earlier, just because you stick with quads does not make for a
tidy, easy-to-work-with mesh. One key to a well-constructed object is creating
well-dei ned face loops. Face loops are simply strings of quads, which are
most useful when they follow the contours of an object.
Face loops that match the contours of an object help avoid subdivision
artifacts, and allow artists to easily add detail with commands that can select
( Select Loop ) and split ( Split Loop ) whole loops at a time. A face loop down
the back of a human character or around a cheek can easily become two or
four loops, and the individual points can be tweaked to add spinal indentation
or muscle dei nition. Throughout the later chapters of this topic as we get into
the modeling process, you will see repeatedly how we start with, maintain,
and create contour-matching face loops, and then use those loops to add
detail. Generally speaking, the better your face loops are, the more closely
your low-polygon base mesh will resemble the high-resolution subdivided
version, because you are more ei ciently dei ning the contours of the shape.
Avoiding Poles
Inevitably, as face loops of polygons collide there will be places on the model
where several quads come together in an uncomfortable fashion (i.e., more
than four edges converging on a single vertex). These conl uences are known
as poles, and can cause subdivision artifacts similar to those caused by
n-gons and triangles. (Like a face, a vertex will subdivide best when it has four
evenly spaced edges coming into it.) A pole can be seen in the center of the
subdivided nine-sided polygon in Figure 2 3.
Fig. 2.4 The side of the model is modii ed so that an edge loop can follow the body contours. This will help
when shaping the ribs and abdomen. You will see this again in Chapter 6.
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