9

702 Chapter 8: Modifiers
the higher-detail areas are still in effect, but you
controlthemindirectlybymeansofthemore
widespread sub-objects at the lower level.
Sub-object animation is supported only at
the lowest level of detail: Base Level. This is
accomplished by animating the mesh belo w the
HSDS mo difier. To apply deformation animation
after HSDS modeling, first convert the object to an
editable mesh by right-clicking the modifier sta ck
and choosing Collapse All.
The adaptive tessellation automatically subdivides
polygons as needed to maintain a smoothly curved
surface when transforming mesh sub-objects. You
can use a preset or provide custom settings.
Impor tant: HSDS models are not passed up the modifier
stack. The HSDS modifier takes a polygon mesh as input,
and outputs a triangle-based mesh.
Also, The HSD S modifier does not handle changes
to the modified object’s topology, such as altering
a sphere’s Segments setting. Topology changes to
the input mesh results in the loss of all edits made
in the HSDS modifier.
Procedure
To use the HSDS modifier:
1.
Apply the HSDS modifier to an object.
By default, the HSDS modifier doesn’t convert
non-quadrilateral polygons to quads. Because
the modifier works best with four-sided
polygons, it’s recommended you perform the
conversion if necessary.
2. If the object contains any non-quadrilateral
polygons, in the HSDS Parameters dialog, turn
on Force Quads. Click Yes in the Force Quads?
dialog that appears.
Note: Upon conversion to quads, the modifier
automatically performs one level of subdivision
with smoothing (like MeshSmooth (page 1–722)
with one iteration) on the object to which
it’s applied. Thus, for best results, use it with
relatively low-polygon objects. For example, if
you usually work with the Sphere object at the
default 3 2 segments, use a 16-segment sphere
with HSDS.
Iftheobjectismadeupofquadsonly,Force
Quads isn’t available because no conversion is
necessar y.
3. Choose a sub-object mode at which to
subdivide.
The object is covered with a gold control
grid (or, in Ver tex sub-object mode, a w h ite
grid with blue vertices), indicati ng that the
entire mesh is available for subdivision and/or
sub-object transformation at base level.
4. Select one or more sub-objec ts.
5. Click the Subdivide button.
The modifier aga in subdivides and smoothes
the selected sub-objects as well as al l
surrounding polygons. The resultant
sub-objects reside at a higher level of detail,
as indicated by the addition of a level in the
Subdivision Stack. Now the control grid
shows only polygons at the new level. With
sub-objects other than E lement, this typically
covers only part of the object’s surface.