Inorganic Modeling
Inorganic modeling is not the easiest approach for polygonal model-
ing if you need precision. However, polygons can do a great job if
you plan the mesh and use it wisely. Here we discuss techniques for
successful inorganic modeling.
Soft Edges
The look of edges is very important in the creation of realistic inor-
ganic objects. Cut objects are among the few real-life objects that
have sharp edges, similar to those we get when creating box primi-
tives in 3D applications. In 3D, the corners of inorganic objects
must have at least a hint of a soft edge to improve the look and real-
ism of the objects (the shading also benefits from edges that are not
too sharp). In this section we describe how to control the creation of
hard and soft edges, using Figures 3-43 to 3-52 as examples.
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Chapter 3 – Polygon Subdivision
Figure 3-41
Figure 3-42
62
Chapter 3 – Polygon Subdivision
Figure 3-43: There is not enough tension to hold the box’s shape after
subdivision.
Figure 3-44: Adding edges improves the tension and holds the box shape.
Figure 3-45: When the extra edges are too close to the original box edges,
the tension is higher and the border gets sharper; when the extra edges are
farther away, the border gets rounder.
When there are extraordinary vertices (valence other than 4, which
is the case of the vertices on the top border of the cylinder in Figure
3-48), the subdivision algorithm has to perform operations to com-
pensate for the lack of vertices.
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Chapter 3 – Polygon Subdivision
Figure 3-46: In this example we see clearly how the subdivision performs a
smoother look to the box.
Figure 3-47: The closer the edges, the sharper the border.
Figure 3-48: In this case, where there is a valence of 3, there is one vertex
missing that keeps it from having an ordinary valence of 4.
To correctly generate the cap polygons in order to avoid unwanted
tension during subdivision, select the top polygon, extrude up, scale
down, and move down to align with the top edges, as shown in Fig-
ure 3-50.
Repeat the operation.
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Chapter 3 – Polygon Subdivision
Figure 3-49: When we see the result without the wireframe, some ripples
appear on the smoothed border.
Figure 3-50
Figure 3-51
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