Lattices make it easy to deform a large amount of
geometry at once. They allow you to deform objects by warping the 3D
space around them. A lattice is a control box with a variable resolution,
looking rather like scaffolding surrounding an object.
When you move a point on a lattice, its original location
in space is mapped to its new location. This warps the space between
points and objects that are affected by the lattice become distorted.
Lattice deformations have two parts:
• A Lattice object.
• A Lattice deformation operator on each
object deformed by the lattice.
You can set the properties for these parts independently
so that several objects can be deformed in different ways by the same
lattice object.
• Unlike in SOFTIMAGE|3D,
lattices are not a special type of geometry. You can select and transform
points, move points, create clusters, assign cluster centers, apply
deformations, use shape animation, and so on, just as with other 3D
objects.
• Lattices do not need to be the parent of
the deformed objects. However, to obtain similar results to SOFTIMAGE|3D
when transforming lattices, make the deformed objects the children of the lattice.
• Scenes with lattice animation might not
be imported correctly. There may be differences because transitions
in XSI are between two shape clips, while in SOFTIMAGE|3D transitions
are between all shape keys. You can fix this problem in the animation
mixer by mixing weight curves instead of using transitions.
Creating and ApplyingLattices
You can create a lattice and apply it to an object
at the same time.
To create and apply a lattice
1. Select the object, branch, group, model, points,
or clusters you want to deform.
2. Choose Get > Primitive >
Lattice. A lattice is created to fit the object and is automatically
parented to the deformed object. The lattice’s property editor
opens.
3. You can set the lattice’s subdivisions
in each axis; more subdivisions give greater resolution for the deformation.
You can also set the interpolation type along
each axis. Curve yields smoother deformations
than Linear.
4. Deform the lattice in any way. For example,
you can select and move points, use clusters, or apply any other deformation
to it. You can also animate the lattice’s deformation.
As the lattice deforms, the object deforms with
it.
Applying an ExistingLattice
If a lattice object already exists in the scene, you
can use it to apply a deformation.
To apply an existing lattice
1. If necessary, create a new lattice by first deselecting
all objects then choosing Get > Primitive >
Lattice. A lattice is created and the Lattice property editor
opens. You can set the lattice’s subdivisions and interpolation
type.
2. Select the object, branch, model, points, or
clusters you want to deform.
3. Choose Deform >
by Lattice from the Model, Animate, or Simulate toolbar.
4. Pick the lattice. The Lattice deformation property
editor opens.
5. Deform the lattice in any way.
Setting the Scope of Lattice Deformations
By default, all points on an object are deformed by
a lattice no matter where they are in space. You can set the Deformation
Scope in the Lattice deformation property editor so that only
those points that are within the lattice object itself are affected:
• All Points deforms
the entire object no matter where it is. The deformation space is extrapolated
beyond the lattice object’s volume.
• Falloff Relative to
Lattice’s BBox deforms only those points within the influence
of the lattice’s bounding box. This is similar to local lattices
in SOFTIMAGE|3D. With this option, you can choose which bounding box to use:
- Predeformed BBox uses
the lattice’s original size as set on the lattice object’s
property editor.
- Deformed BBox uses
the lattice’s current bounding box after any deformations have
been applied.
• You can also define the Start
and End of a falloff of the lattice’s
effect relative to the bounding box; this prevents points from jumping
as soon as they enter the lattice’s influence.
Scaling
You can control how an object is affected when the
lattice object is scaled by setting the Scaling Mode
option in the Lattice deformation property editor:
• No Scaling—The
deformed object is not scaled when the lattice object is scaled. However,
the deformed object is still affected as the lattice’s points
move when scaled.
• Treat Scaling as Deformation—The
deformed object is scaled before the lattice deformation is applied.
• Apply Scaling to Geometry
(SI3D)—The lattice deformation is applied first, then the
deformed object is scaled. This is the behavior in SOFTIMAGE|3D.
