Operation: This tool creates a closed cubic B-Spline curve with
i+3 control points in the XY plane. The control points are arranged
in a circle of radius 1 centered around the origin. This gives the curve
a circular appearance (see image above) but it is not a true circle.
Use the NURBCircle
tool (see below) to create a true circle instead.
Note: i must be atleast 3. The first three control
points of the new curve will be identical to the last three.
Additionally, the curve will be marked as closed, and the generation
of multiple points will be enabled, so that point
edit actions know that they may need to move two points.
See also section
Multiple Points.
Operation: The NURBCircle tool creates a full circular NURBS curve
of radius 1 in the XY plane located at the origin.
Note: The NURBS curve created by the NURBCircle tool is rational
(uses weights). This means, editing the curve (e.g. moving control points)
may lead to unpredicted results (the curve does not behave exactly
as wished). Use a closed B-Spline
created with the Closed BSpline Tool (see above) if you want to edit
the curve further.
You can use this circle to easily create a NURBS-torus by moving
the circle along X and then revolving it. The amount of movement
determines the radius of the torus, whereas the radius of the circle
determines the thickness.
Operation: The TrimRect tool creates a piecewise linear
NURBS curve of rectangular
shape, that fits in the (u,v) parameter space of a NURBS patch, for use
as trim curve.
Note: To fit the curve to the parameter space of a NURBS patch,
the current level should be inside the NURBS patch.
If the current level is not inside a NURBS patch, a
curve with the coordinates (-1,-1), (-1,1), (1,1), and (1,-1)
will be created instead.
See section
Trim Curves for a more
detailed discussion of trim curves and how to use this rectangular
curve.
Arguments: The concat tool takes two NURBS curves from
the selection.
Operation: The selected NURBS curves will be concatenated
and a new third curve will be created.
Note: If one of the curves has weights, the resulting curve
will have weights too. If the knot type of the first curve
is custom, it will be converted to NURB, otherwise the knot type
of the new curve will be that of the first selected curve.
Due to those changes of the knot values the resulting curve might
differ from the original curves.
See also section
ConcatNC Object.
The original NURBS curves will not be deleted by this tool.
Left: original curve, Right: resulting split curves for t=0.5
Arguments: The split curves tool takes a single NURBS curve from
the selection and additionally requests a parametric value.
Operation: The selected NURBS curve will be split into two
new NURBS curves at the designated parametric value. The splitting process
involves application of knot insertion, so that both new curves will
get a custom knot vector.
Note: The original selected NURBS curve will be changed and
form the first of the two new curves, so you may want to keep a copy
of it somewhere.
Arguments: The refine tool takes a number of NURBS curves from
the selection.
Operation: The knot vectors of the selected NURBS curves will be
refined by inserting a knot in the middle of each inner knot interval
without changing the shape of the curve.
Note: Because a new knot is inserted in the middle of
each interval, knot vectors of type NURB and B-Spline will
not change in type. See the image above for an example of a
successive refinement of a simple NURBS curve. Note that the shape
of the curve does not change, but the position of
certain control points does.
If you want to refine a curve with new control points and not
change the position of existing control points, use the NCAttribute
property GUI instead (simply increase the length of the curve
by oldlength-1).
Arguments: The clamp tool takes a number of NURBS curves from
the selection.
Operation: The knot vectors of the selected NURBS curves will be
changed using knot insertion so that the first and the last knot
have a multiplicity equal to the order of the curve,
without changing the shape of the curve. The curve will
interpolate the first and the last control point afterwards.
The knot type of the curve will be changed to custom.
Left: original curve, Right: a knot has been inserted 1 time at t=0.5
Arguments: The insert knot tool takes a number of NURBS curves from
the selection and requests two additional values, a parametric value t
and an integer value i.
Operation: The specified knot (t) will be inserted i
times into the knot vector of the selected curves, without changing the
shape of the curve(s).
The knot type of the curve will be changed to custom.
Curvature Plot (top) of simple NURBS curve (bottom)
Arguments: The plot curvature tool takes a number of NURBS curves from
the selection and requests three additional values: the number of data
points, the width value and the height value.
Operation: A new NURBS curve, depicting the curvature of the selected
NURBS curve, will be created for each of the selected
NURBS curves. The curvature plots will have a length defined by the
number of data points and will be scaled to the specified width
and by the specified height value. See also the image above.
Arguments: The shift closed B-Spline tool takes a number of
NURBS curves, that should be closed B-Splines, from the selection and
requests one additional integer parameter.
Operation: The control points of the curve(s) will be shifted, so that
the second control point will be the first after this operation.
The shifting process will be repeated according to the parameter value
given. Eventually selected points will still be selected after this
operation.
Arguments: The collapse tool expects a selected NURBS curve
and a number of selected (tagged) control points (see section
Selecting Points for information on how
to select (tag) control points).
Operation: The selected control points will be made a
single multiple point, all points will get the coordinate values
of the last tagged point.
Arguments: The explode tool expects a selected NURBS curve
and a number of selected (tagged) multiple points (see section
Selecting Points for information on how
to select (tag) control points).
Operation: The points forming the selected multiple points will
be made to simple points again and may be edited separately.
Note that even though you might have exploded some multiple points
Ayam will re-create them on several occasions like reading
of a scene, inserting/deleting points, and applying the NURBCurveAttrib
property if they still have identical coordinate values. In other
words, you should immediately edit the control points after exploding!
Arguments: The build from curves tool takes a number of NURBS curves from
the selection.
Operation: The selected NURBS curves will be parsed, all curves
that are of equal length or longer than the first selected curve
will be used to form a new NURBS patch of the following dimensions:
Width: length of the first selected curve,
Height: number of used curves. Other parameters (Knot-Type_U, Knots_U
etc.) are taken from the first curve.
Note: The NURBS curves are not deleted afterwards.