9

FFD(Cyl) Space Warp 99
Cylinder primitive. Note that these spinners don’t
exist in the object-modifier version of the FFD.
Label—Displays the current number of controls
points in the lattice (for example: 4x8x4).
Set Number of Points—Displays a dialog containing
three spinners labeled Side, Radial, and Height,
plus OK /Cancel buttons. Specify the number of
control points you want in the lattice, and then
click OK to make the change.
Side—The number of control points around the
perimeter of the lattice.
Radial—The number of control points, radially,
from the center to the outer perimeter of the lattice.
Height—The number of control points along the
height of t he lattice.
Note: Make changes to the dimensions before you
adjust the positions of the lattice control points.
When you change the number of control points
with this dialog, any adjustments you’ve already
made to the cont rol points are lost; however, you
can undo this use of the dialog.
Display group
TheseoptionsaffectthedisplayoftheFFDin
viewports.
Lattice—When on, lines are d r awn connecting the
control points to make a grid. Although viewports
can become cluttered when these extra lines are
drawn, t hey help to visualize the lattice.
Sour ce Volume—When on, the control points and
lattice are displayed in their unmodified state. This
display is helpful when you’re adjusting the source
volume to affect specific vertices that lie within or
w ithout it. See the All Vertices and Only in Volume
options, later in this topic.
Deform group
These options provide controls that specify which
vertices are affected by the FFD.
Only I n Volume—When on, only vertices that lie
insidethesourcevolumearedeformed.Vertices
outside the source volume are not affected. This is
the default choice.
All Ver tices—When on, all vertices are deformed
regardless of whether they lie inside or outside
thesourcevolume,dependingonthevaluein
theFalloffspinner. Thedeformationoutside
thevolumeisacontinuousextrapolationofthe
deformation inside the volume. Note that the
deform at ion can b e ext reme for points far away
from the source lattice.
Fa lloff—This spinner, enabled only when you
choose All Vertices, determines the distance from
the lattice that the FFD effect will decrease to zero.
When this spinner is set to 0, it’s effectively turned
off, and there is no falloff; that is, all vertices are
affected regardless of their distance from the
lattice. The units of the Falloff parameter are
specified relative to the size of the lattice: A falloff
of 1 means that the effect will go to 0 for points that
arealatticewidth/length/heightawayfromthe
lattice (depending on which side they are on).
Tensi on/Continuity —Lets you adjust the tension
and continuity of the deformation splines.
Although you can’t see the splines in an FFD, the
lattice and control points represent the structure
that controls the splines. As you adjust the control
points, you alter the splines (which m ove through
each point). The splines, in turn, deform t he
geometry of the object. By a ltering the tension and
contin uity of the splines, you alter their effect on
the object.
Selection group
These options provide additional methods of
selecting control points. You can toggle any
combination of the three buttons to select in one,
two, or three dimensions at once.
AllX,AllY,AllZ—When one of these buttons is on
and you select a control point, all control points