8

856 Chapter 8: Modifiers
When R ender ing—
Tessellation is updated only
when the object is rendered.
Manually—Tessellation is updated only w hen the
user clicks Update.
Update—Click to update tessellation. Has no effect
unlessManuallyistheactiveupdateoption.
Tr im/Ex tend M odifier
Select a shape. > Modify panel > Modifier List >
Object-Space Modifiers > Trim/Extend
Select a shape. > Modifiers menu > Patch/Spline Editing
>Trim/Extend
The Trim/Extend modifier is used primarily
to clean up overlapping or open splines in a
multi-spline shape so that lines meet at a single
point. As with the Fillet/Chamfer modifier, this
modifier operates on the splines at the sub-object
level in the shape. When applied to a selection of
multiple splines, Trim/Extend works as it does on
asinglespline.
To trim, you need intersecting splines. Click
the portion of the spline you want to remove.
Thesplineissearchedalongitslengthuntilit
hits an intersecting spline, and deleted up to
theintersection.Ifthesectionintersectsatboth
ends, the entire section is deleted up to the two
int ersections. If the section is open on one end and
intersects at the other, the entire sect ion is deleted
uptotheintersectionandtheopenend. Ifthe
section is not intersected, nothing happens.
To extend, you need an open spline. The end of
thesplinenearestthepickedpointisextended
until it reaches an intersecting spline. If there is
no intersecting spline, nothing happens. Curved
splines extend in a direction tangent to the end of
the spline. If the end of a spline lies directly on a
boundary (an intersecting spline), then it looks for
an intersection further along.
Note: As of version 3 of 3ds Max, Edit/Editable
Spline (page 1–284)
includes interactive
trim/extend functions. The only reason to use this
modifier is to apply it at a specific location on the
stack.
Before and after initial use of Tr im
Before and a fter second use of Trim on above spline
Before and after using Extend
Procedure
To trim a shape using the Trim/Ex tend modifier:
1.
Create an open Line shape (page 1–265) in the
form of roughly concentric overlapping circles.
2. Apply the Trim/Extend mo difier.
3. Click Pick Locations.
4. Cl ick t he inner s pline sections of t he concentric
shape to t rim them away, or click the open
spline segment to extend the spline.