TYPE: SOP State
TITLE: Curve Operation

The Curve operation creates polygons, NURBS and Bezier curves.

To build a curve, click with the left mouse button to specify the data points,
then right-click to finish. Shift-click close to any end of the curve to extend
the curve in that direction by adding new points. For added precision, bring up
the operation dialog from the viewer menu or by typing
\'${h.pane.gview.operation_parameters}\', then type the points one by one,
clicking on "Add Point" to add each point.

See the Ctrl-right-mouse menu for a full list of options. Any options chosen
from that menu will be remembered the next time you start a new curve operation.
For example, if you want to always create NURBS curves, choose "NURBS curve"
from the Ctrl-right-mouse menu. Alternatively, choose "NURBS" from the
"Primitive Type" menu above the viewport, the Right-click on that menu to make
the NURBS option the current default (see "Make Current Value Default").

If you are building a NURBS or Bezier curve, the data points can be interpreted
as control vertices (CV's), breakpoints, or freehand points. A curve built with
breakpoints will run through each of the breakpoints.

To reference other geometry (points or breakpoints) such that any changes in
that geometry will reshape the curve built in this operation, turn on snapping
to points and/or breakpoints and enable "Snap Consolidate" in the Snap Options
dialog above the viewport. Referencing the breakpoints of other curves is a good
way of building smart curve networks. You can always convert all references to
numerical coordinates using the Ctrl-right-mouse menu.

When snapping to primitives, it is possible to snap to the curve you are
building.  This may sometimes be undesirable.  To avoid self-snapping lower the
gravity entry in the Snap Options.

The points created with this operation are not individually animatable here.
Append a Transform operation or other deformers to animate the curve points.

See also: Add, Fit, PolySpline, PolyLoft, PolySplit
