Surface ExtendFace

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Sections

CurveOnMesh

Surface

Menu location
Surface ExtendFace
Surface → Extend face
Workbenches
Surface
Default shortcut
None
Introduced in version
0.17
See also
None

Description

Surface ExtendFace extrapolates an existing face or surface at its boundaries with its local U and V parameters.

Left: original face. Right: extended face.

Usage

Make sure you have an object that has faces. The object could be created with the Surface Workbench but it could also be any other object, for example, created with Part or PartDesign.
Select the face to extend by clicking on it on the 3D view.
Press Extend face.

Options

This command doesn't have any options. Either it works with the selection or not.

Properties

A Surface Extend object (Surface::Extend class) is derived from the basic Part Feature (Part::Feature class, through the Part::Spline subclass), therefore it shares all the latter's properties.

In addition to the properties described in Part Feature, the Surface Filling has the following properties in the property editor.

Data

Base

DataFace (LinkSub): the subelement from an object that will be extended; it must be a face.
DataTolerance (FloatConstraint): it defaults to 0.1.

DataExtend UNeg (FloatConstraint): it defaults to 0.05. The ratio of the local U parameter that will be extended in the negative direction.
DataExtend UPos (FloatConstraint): it defaults to 0.05. The ratio of the local U parameter that will be extended in the positive direction.
DataExtend USymetric (Bool): it defaults to true, in which case DataExtend UNeg and DataExtend UPos will have the same value.

DataExtend VNeg (FloatConstraint): it defaults to 0.05. The ratio of the local V that will be extended in the negative direction.
DataExtend VPos (FloatConstraint): it defaults to 0.05. The ratio of the local V direction that will be extended in the positive direction.
DataExtend VSymetric (Bool): it defaults to true, in which case DataExtend VNeg and DataExtend VPos will have the same value.

DataSampleU (IntegerConstraint): it defaults to 32.
DataSampleV (IntegerConstraint): it defaults to 32.

View

Base

ViewControl Points (Bool): it defaults to false; if set to true, it will show an overlay with the control points of the surface.

Scripting

See also: FreeCAD Scripting Basics.

The Surface Extend tool can be used in macros and from the Python console by adding the Surface::Extend object.

The face to extend must be assigned as a LinkSub to the Face property of the object. It must contain only a single face.

import FreeCAD as App
import Draft

doc = App.newDocument()

a = App.Vector(-20, -20, 0)
b = App.Vector(-18, 25, 0)
c = App.Vector(60, 26, 0)
d = App.Vector(33, -20, 0)

points = [a, App.Vector(-20, -8, 0), b, c,
          App.Vector(37, 4, 0), d,
          App.Vector(-2, -18, 0), a]
obj = Draft.make_bspline(points)
doc.recompute()

if App.GuiUp:
    obj.ViewObject.Visibility = False

surf = doc.addObject("Surface::Filling", "Surface")
surf.BoundaryEdges = [(obj, "Edge1")]
doc.recompute()

# ---------------------------------------------------------
points_spl = [App.Vector(-10, 0, 2),
              App.Vector(4, 0, 7),
              App.Vector(18, 0, -5),
              App.Vector(25, 0, 0),
              App.Vector(30, 0, 0)]
aux_edge = Draft.make_bspline(points_spl)
doc.recompute()

surf.UnboundEdges = [(aux_edge, "Edge1")]
doc.recompute()

# ---------------------------------------------------------
surf_extended = doc.addObject("Surface::Extend", "Surface")
surf_extended.Face = [surf, "Face1"]
doc.recompute()