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Display Controls for NURBS Models 1117
When Relational Stack is on, NURBS maintain full
relational modeling on the modifier stack (page
3–760). When th is toggle is off (the default),
then using the modifier stack converts surfaces
into independent CV surfaces before applying
modifiers. Surfaces on the stack behave in a
nonrelational way. If your NURBS model contains
no dependent surfaces, then it behaves the same on
the stack regardless of the Relational Stack setting.
However, the results are still faster if Relational
Stack is turne d off.
When Relational Stack is off, there is no overhead
of copying the data from the relational model,
and no need to compute the relational sur faces,
so performance is faster.
Tip: To improve performance still further, display
surfaces as shaded lattices (see Display Controls for
NURBS Models (page 1–1117)). With Relational
Stack off and Shaded Lattice chosen, NURBS
objects perform on the stack about as well as mesh
objects do.
Procedure
To use nonrelational NURBS surfaces:
1.
Make sure Relational Stack is off and Shaded
Lattice is chosen.
2. Set up your modifiers and animation.
3. If your model has only independent CV
surfaces,youcanrenderitnow. Ifithas
relational surfaces such as blends or lofts, then
before you render, choose the NU RBS model at
the bottom of the stack, and turn on Relational
Stack.
When you return to the top of the modifier
stack, performance is slower but dependent
surfaces are accurate. The modified NURBS
modellooksdifferentthanitdidwiththe
nonrelational stack. Usually the difference in
appearance isn’t g reat, but the nonrelational
stack can show anomalies such as cracks
between Blend surfaces.
Dis play Cont rol s f or NUR B S
Models
Modify panel > Selec t NURBS object. > General rollout
> Display group, Sur face Display group, and NURBS
Creation Toolbox button
Modify panel > Sele ct NURBS object. > Right-click in
viewport. > Display commands on the To ols 1 (upper-left)
quadrant of the qua d menu
The check boxes on the General rollout for a
NURBS curve or surface control how the object
is displayed in viewports. If all check boxes are
turned off, the NURBS object is invisible (except
for the white bounding-box indicators display ed
in shaded viewports when the object is selected).
An additional rollout, Display Line Par ameters
(page 1–1119), contains controls for how surfaces
display in viewports.