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846 Chapter 8: Modifiers
rollout, such as Line (page 1–270), Circle (page
1–273), Arc (page 1–274),andSection (page
1–282). Splines can also be created using the
Creat e Line command in an Editable Spline or
and Edit Spline modifier.
• Splines are edited by applying an Edit Spline
modifier to the sele cted spline object or editing
parameters in an Editable Spline. Editing
splines changes the patch surface created by the
Surface modifier .
• To add splines to a spline object, use the Attach
command in the Edit Spline modifier.
• Within a spline object, splines need not be
cont inuous. A spline object may consist of
ten splines, for example. As long as the spline
vertices are coincident, or close enough for the
Threshold parameter in the Surface mo difier to
weld them together, a surface will be generated.
Pr ocedur es
Example: Understanding valid splines:
1.
In the Top viewport, use Create
panel > Shape > NGon to create three NGons:
a three-sided, four-sided, and five-sided NGon,
each about 100 units wide.
2. Make sure that a
ll the splines form one
object. DothisbyapplyinganEditSpline
modifier to one of the NGons and using Attach
to add the rema
ining NGon objec ts.
3. Choose Modifiers menu > Patch/Spline Editing
> Surface from the Modifier List.
Notice that the three- and four-sided splines
formed patches but the five-sided NGon did
not. Thefive-sidedsplinedoesnotforma
three- or four-sided closed region. To make it
a valid spline, a line must bisect the NGon to
form a three- and four-sided region.
4. In the stack display, choose the Edit Spline
modifier again. Turn on Create Line on the
Geometry rollout, and create a line that bisects
the five-sided NGon.
Thestartandendpointsofthelineshould
overlap the vertices on the NGon. Being exact
is not critical; the Threshold parameter fuses
spline vertices based on their proximity.