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FFD (Box/Cylinder) Modifiers 679
lattice. Note that the point dimensions also show
up beside the modifier name i n the stack list.
Lattice dimensi ons—The text displays the cur rent
number of control points in the lattice (for example
3x4x4).
Set Number of Points—Displays a dialog containing
three spinners labeled Length, Width, 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.
Wa rni ng: Make changes to the lattice dimensions
before you adjust the positions of the lattice control
points. When you chang e the number of control points
with this dialog, you lose any adjustments you’ve already
made to the control points. (You can undo this dialog.)
Display group
Affects the display of the FFD in the viewports.
Lattice—Draws lines connecting the control points
to make a grid. Although the viewports can
sometimes b ecome cluttered when these extra
lines appear, they help to visualize the lattice.
Sour ce Volume—Displays the control points
and lattice in their un modified state. This is
an important display when you’re adjusting the
source volume to affect specific vertices that lie
inside or outside it.
Tip: Toseewhichpointslieinthesourcevolume
(andthereforewillbedeformed),temporarily
deactivate the modifier by clicking to turn off the
light bulb icon in the modifier stack display.
Deform group
Provides cont rols that specif y which vertices are
affected by the FFD.
Only In Volume—Deforms vertices that lie inside
thesourcevolume. Verticesoutsidethesource
volume are not affected.
All Vertices—Deforms all vertices regardless of
whether they lie inside or outside the source
volu me depending on the value in the Falloff
spinner . The deformation outside the volume is
a continuous extrapolation of the deformation
inside the volume. Note that the deformation can
be extreme for points far away from the s ource
lattice.
Fa lloff—Determines the distance from the lattice
that the FFD effect w ill decrease to zero. Available
only when you choose All Vertices. When set to 0,
it’s effect ively tur ned off, and there is no falloff. All
vertices are affected regardless of how far they are
from the lattice. The units of the Falloff parameter
areactuallyspecifiedrelativetothesizeofthe
lattice. A falloff of 1 means that the effect will go to
0 for points that are a lattice width/length/height
away from the lattice (depending on which side
they are).
Tensi on/Continuity —Adjusts the tension and
continuity of the deformation splines. Although
you can’t actually see t he 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 move through
each of the points). The splines, in turn, deform
the geometry of the object. By altering the tension
and continuity of the splines, you alter their e ffect
on the object.
Selection group
Provides additional methods of selecting the
control points. You can toggle the state of any
combination of the three buttons to select in one,
two, or three dimensions at once.
AllX,AllY,AllZ—Selects all control points along
the specified local dimension when you select a
control point. By turning on two buttons, you can
select all control points in two dimensions.