8

FFD(Cyl) Space Warp 95
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 d ia log containing
three spinners labeled Side, R adial, 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 the 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 t he control points are lost; however, you
can undo t his use of the dialog.
Display group
TheseoptionsaffectthedisplayoftheFFDin
viewports.
Lattice—When on, lines are drawn connecting the
control points to make a grid. Although viewports
can become cluttered when these extra lines are
drawn, they 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 Al l 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 In Volume—When on, only vert ices 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 ation can be extreme 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 w i l l decrease to zero.
When this spinner is set to 0, it’s effect ively turned
off, and there is no falloff; that is, all vert ices 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 wil l 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 t he control
points, you alter the splines (which move through
each point). T he splines, in turn, deform the
geometry of the object. By a ltering the tension and
continuity 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