Modeling the Details - Blender Master Class: A Hands-on Guide to Modeling, Sculpting, Materials, and Rendering - page 56

on the mesh. The shortcut for Edge
operators, including Tagging, in Edit
mode is ctrl -E. Edges can be marked
as Sharp, which allows operators like
Bevel and Edge Split to work only on
these edges. They can also be given
a crease value, either from the ctrl -E
menu or with shift -E, which tells the
Subsurf modifier not to smooth these
edges when doing subdivision, result-
ing in nice sharp edges.

Sharp Edges and Subdivision
Creasing is one way to achieve a sharp
crease in a subdivided mesh; another
way is with support loops . Support loops
work by placing two or more edge
loops close together at the edge of a
form. When the mesh is subdivided,
the new geometry can't be smoothed
out as much because the extra geom-
etry defines the corner more tightly
(see Figure 5-14).
Both methods have their place.
Support loops are the better choice
when you're trying to produce nicely
beveled edges and need fine control
over precisely how your forms look.
However, if your goal is to produce
very sharp creases or you are working
with simpler models with less extra
topology, creasing is preferable. You
can always mix and match both meth-
ods as the situation demands.
Support loops are also useful
for ensuring that objects subdivide
to give the shapes you want. For
example, Figure 5-15 shows a cube
with a Subsurf modifier applied and
its wireframe visible. With no support
loops, the modifier turns it into a
sphere. With extra support loops run-
ning around the middle of the faces,
the object more closely resembles a
cube, and shifting these support loops
toward the edges of the cube makes
the corners sharper. This is useful
when modeling all sorts of surfaces.

Figure 5-12: Creating the stone carvings. I first blocked out the carvings as
individual pieces over the concept art, using primarily quads. Next, I tagged
some edges as creased (purple) to give sharp edges when subdivided. Finally,
I added Subsurf and Edge Split modifiers to give smooth carvings with sharp
edges where the edges had been tagged. The result uses fewer polygons and
simpler topology than if I had used support loops to produce sharp edges.