Move
or reshape a curve so it touches one or two other curve(s) or surface(s).
Stretch a curve so it touches
another curve
- Choose Curve Edit > Modify > Stretch .
- Select the curve you want to stretch
Two control handles appear
at the ends of the curve.
- Click on the handle you want to touch
to the other curve.
The
handle turns white.
- Hold and (Windows) or and (Mac) to turn on curve snapping.
- Click on the other curve to snap the
handle to it.
- Drag the handle along the curve.
How do I use the curve
stretch handles?
- To change the number of handles, press
the - Handles or +
Handles buttons. The minimum number of handles is 2.
The maximum number is equal to the curve’s degree + 1. For example,
a degree 3 curve cannot have more than 4 handles.
- To change a handle’s location along the
curve, click and drag the purple triangle attached to it.
How do I use the tangent
manipulator?
- Press the Tangent On button
to bring up the manipulator on the active handle.
- Use the manipulator’s arrow head to modify
the position of the curve at that point by sliding it along the
tangent.
- Use the manipulator’s square to scale
the tangent.
- Use the manipulator’s dotted arcs to
rotate the tangent around the X, Y or Z axes.
- Use the manipulator’s axes lines to orient
the tangent along the X, Y or Z axes.
- Press the Tangent Off button
to remove the manipulator.
What if...?
I can’t see edit points
on the curves?
- You may have turned off the display of
edit points, either for this object or the entire scene.
- The curve may have only one span.
Transform a curve so it
intersects two other curves
The Curve Edit > Modify > Transform Curve tool provides a direct way
of positioning or transforming a curve so that it intersects two
rail curves.
Positioning and intersecting
a curve can be done in two ways:
- By moving the curve so that it intersects
the first rail, then “rocking” (rotating) it so that it intersects
the second rail.
- By “dilating” (scaling) the curve, while
preserving its shape characteristics, so that it intersects both
rails. This is different from the Curve Edit > Modify > Stretch tool, which changes the
curvature characteristics of the curve as it stretches it.
Method 1: Translating
and Rotating a curve (rocking)
- Choose Curve Edit > Modify > Transform Curve .
- Select the curve.
Two control handles (circles) appear at the
start and end points of the selected curve.
NoteYou can move the
control handles along the curve by clicking on them and dragging
the small purple arrow along the curve.
- Click on the Translate button
in the window.
- Select the control handle closest to
the first rail.
The
selected handle turns white.
- Turn on Curve snap mode
by holding down the and (Windows) or and (Mac) keys (or Magnet mode
by holding down (Windows) or (Mac) only).
- Click on the first rail curve. Drag to
change the position of the intersection.
The input curve is translated so that the first
control handle intersects the first rail.
- Click on the Rotate button
in the window.
The
second control handle turns white. A manipulator appears at the
location of the first control handle. This can be used to specify
the plane of rotation: XY, YZ, XZ. By default, the curve rotates
in its own plane.
- Turn on Curve snap mode
by holding down the and (Windows) or and (Mac) keys.
- Click on the second rail curve.
The input curve rotates in the specified plane
of rotation, using the first intersection as its rotation pivot,
so that it now intersects the second rail.
The shape of the curve
does not change.
Method 2: Rotating
and Scaling a curve (dilating)
- Choose Curve Edit > Modify > Transform Curve .
- Select the curve.
Two control handles (circles) appear at the
start and end points of the selected curve.
NoteYou can move the
control handles along the curve by clicking on them and dragging
the small purple arrow along the curve.
- Click on the Rotate & Scale button
in the window.
- Click on one control handle.
The selected handle turns
white.
- Turn on Curve snap mode
by holding down the and (Windows) or and (Mac) keys (or Magnet mode
by holding down (Windows) or (Mac) only).
- Click on the rail curve you want to snap
the selected handle to.
- Repeat steps 4 to 6 with the other control
handle.
The input curve is scaled so that both control
handles make contact with the target points on the rail curves.
The curve is modified,
but the general shape characteristics are maintained, as can be verified
by using a curvature comb on the curve (Locators > Curve Curvature ).
How do I use the rotation
manipulator?
The
rotation manipulator appears when you are in Rotate mode
(Rotate button depressed). It
has three axes (X, Y and Z), and a circle along which the selected
handle on the curve rotates. By default, this circle is drawn in
the plane of the curve.