Sketcher CreateBSplineByInterpolation: Difference between revisions

From FreeCAD Documentation
(updated icon and name)
mNo edit summary
 
(33 intermediate revisions by 4 users not shown)
Line 2: Line 2:
<translate>
<translate>


<!--T:1-->

{{Docnav
{{Docnav
|[[Sketcher_CreatePeriodicBSpline|Periodic B-spline]]
|[[Sketcher_CreatePeriodicBSpline|Periodic B-spline by control points]]
|[[Sketcher_CreatePeriodicBSplineByInterpolation|Periodic B-spline by Interpolation]]
|[[Sketcher_CreatePeriodicBSplineByInterpolation|Periodic B-spline by knots]]
|[[Sketcher_Workbench|Sketcher]]
|[[Sketcher_Workbench|Sketcher]]
|IconL=Sketcher_CreatePeriodicBSpline.svg
|IconL=Sketcher_CreatePeriodicBSpline.svg
Line 12: Line 12:
}}
}}


<!--T:2-->
{{GuiCommand
{{GuiCommand
|Name=Sketcher CreateBSplineByInterpolation
|Name=Sketcher CreateBSplineByInterpolation
|MenuLocation=Sketch → Sketcher geometries → Interpolate B-spline
|MenuLocation=Sketch → Sketcher geometries → Create B-spline by knots
|Workbenches=[[Sketcher_Workbench|Sketcher]]
|Workbenches=[[Sketcher_Workbench|Sketcher]]
|Shortcut={{KEY|G}} {{KEY|B}} {{KEY|I}}
|Shortcut={{KEY|G}} {{KEY|B}} {{KEY|I}}
|Version=0.21
|Version=0.21
|SeeAlso=[[Sketcher_CreatePeriodicBSpline|Sketcher periodic B-spline]]
|SeeAlso=[[Sketcher_CreatePeriodicBSplineByInterpolation|Sketcher CreatePeriodicBSplineByInterpolation]]
}}
}}


==Description==
==Description== <!--T:3-->


<!--T:4-->
The [[Image:Sketcher_CreateBSplineByInterpolation.svg|24px]] [[Sketcher_CreateBSplineByInterpolation|Sketcher CreateBSplineByInterpolation]] tool creates a B-spline curve through knot points. See [[B-Splines|this page]] for more information about B-splines.


==Usage== <!--T:5-->
This tool creates a B-spline curve passing through given points. See [[B-Splines|this page]] for more info about B-splines.


<!--T:12-->
==Usage==
See also: [[Sketcher_Workbench#Drawing_aids|Drawing aids]].


<!--T:6-->
# There are several ways to invoke the tool:
#* Press the {{Button|[[Image:Sketcher_CreateBSplineByInterpolation.svg|16px]] [[Sketcher_CreateBSplineByInterpolation|B-spline by knots]]}} button.
#* Select the {{MenuCommand|Sketcher → Sketcher geometries → [[Image:Sketcher_CreateBSplineByInterpolation.svg|16px]] Create B-spline by knots}} option from the menu.
#* Use the keyboard shortcut: {{KEY|G}} then {{KEY|B}}, then {{KEY|I}}.
# The cursor changes to a cross with the tool icon.
# Pick several knot points.
# Optionally press {{KEY|M}} before finishing the input to define the multiplicity of the last defined knot point (this may not always be respected, see [[#Limitations|limitations]] for details).
# Optionally press {{KEY|Backspace}} before finishing the input to delete the last knot point.
# Right-click or press {{KEY|Esc}} to finish the input.
# The B-spline is created, including a set of internal geometry (weight circles and knot points).
# If the tool runs in [[Sketcher_Workbench#Continue_modes|continue mode]]:
## Optionally keep creating B-splines.
## To finish, right-click or press {{KEY|Esc}}, or start another geometry or constraint creation tool.


==Notes== <!--T:7-->
# Press the {{Button|[[File:Sketcher_CreateBSplineByInterpolation.svg|16px]] [[Sketcher_CreateBSplineByInterpolation|Create B-spline by Interpolation]]}} button.
# Create a series of points by clicking in the [[3D_view|3D view]]. While the command is active, the created points are connected with straight lines.
# Optionally press {{KEY|M}} before terminating the input to define the multiplicity of the knot at the last defined point (note that this may not always be respected; see limitations for details).
# Optionally press {{KEY|Backspace}} before terminating the input to delete the last created control point.
# Right-click to terminate the input and generate the curve.
# Depending on preferences, the tool may remain active to trace a new curve. Right-click again to exit the command.
* After a B-spline is created, it is possible to define the weight of the control points by changing the radii of the weight circles. The equality constraints on the circles need to be deleted first. The radius constraint is arbitrary, the weight of the control points will be defined by the relative radii of the circles. It works similar to gravity: the bigger a circle is in relation to the others, the more the curve will be attracted to the control point.
* The visibility of the control polygon, the curvature comb, the degree and the knot multiplicity can be toggled on/off from the [[Sketcher_Workbench#Sketcher_B-spline_tools|B-spline tools]] toolbar.
* Check out the other tools in the [[Sketcher_Workbench#Sketcher_B-spline_tools|B-spline tools]] toolbar for more B-spline editing tools.


<!--T:8-->
==Limitations==
See [[Sketcher_CreateBSpline#Notes|Sketcher CreateBSpline]].


==Limitations== <!--T:9-->


<!--T:10-->
* The resultant curve is no different than the curve defined through control points. So all limitations of a non-periodic B-spline apply.
* The resultant curve is no different from a (non-uniform) B-spline defined through control points. So all related limitations apply. See [[Sketcher_CreateBSpline#Limitations|Sketcher CreateBSpline]].
* The B-splines created are always cubic (i.e. with degree 3)
* The defined multiplicity may not always be respected
* The created B-splines are always cubic (i.e. with degree 3).
* The defined multiplicity may not always be respected:
** For a periodic spline, the first knot (coincident with last) always has a multiplicity of 2.
** For a non-periodic spline, the first and last knots always have a multiplicity of 4.
** For a non-periodic spline, the first and last knots always have a multiplicity of 4.
** If the points just before and just after have multiplicities >=3, the piece between these two is fully continuous, and this (middle) point will only be constrained with point-on-object. If a knot is needed, consider using the insert knot tool.
** If the points just before and just after have multiplicities >=3, the piece between these two is fully continuous, and this (middle) point will only be constrained with point-on-object. If a knot is needed, consider using the insert knot tool.




<!--T:11-->


{{Docnav
{{Docnav
|[[Sketcher_CreatePeriodicBSpline|Periodic B-spline]]
|[[Sketcher_CreatePeriodicBSpline|Periodic B-spline by control points]]
|[[Sketcher_CreatePeriodicBSplineByInterpolation|Periodic B-spline by Interpolation]]
|[[Sketcher_CreatePeriodicBSplineByInterpolation|Periodic B-spline by knots]]
|[[Sketcher_Workbench|Sketcher]]
|[[Sketcher_Workbench|Sketcher]]
|IconL=Sketcher_CreatePeriodicBSpline.svg
|IconL=Sketcher_CreatePeriodicBSpline.svg

Latest revision as of 09:27, 18 April 2024

Other languages:

Sketcher CreateBSplineByInterpolation

Menu location
Sketch → Sketcher geometries → Create B-spline by knots
Workbenches
Sketcher
Default shortcut
G B I
Introduced in version
0.21
See also
Sketcher CreatePeriodicBSplineByInterpolation

Description

The Sketcher CreateBSplineByInterpolation tool creates a B-spline curve through knot points. See this page for more information about B-splines.

Usage

See also: Drawing aids.

  1. There are several ways to invoke the tool:
    • Press the B-spline by knots button.
    • Select the Sketcher → Sketcher geometries → Create B-spline by knots option from the menu.
    • Use the keyboard shortcut: G then B, then I.
  2. The cursor changes to a cross with the tool icon.
  3. Pick several knot points.
  4. Optionally press M before finishing the input to define the multiplicity of the last defined knot point (this may not always be respected, see limitations for details).
  5. Optionally press Backspace before finishing the input to delete the last knot point.
  6. Right-click or press Esc to finish the input.
  7. The B-spline is created, including a set of internal geometry (weight circles and knot points).
  8. If the tool runs in continue mode:
    1. Optionally keep creating B-splines.
    2. To finish, right-click or press Esc, or start another geometry or constraint creation tool.

Notes

See Sketcher CreateBSpline.

Limitations

  • The resultant curve is no different from a (non-uniform) B-spline defined through control points. So all related limitations apply. See Sketcher CreateBSpline.
  • The created B-splines are always cubic (i.e. with degree 3).
  • The defined multiplicity may not always be respected:
    • For a periodic spline, the first knot (coincident with last) always has a multiplicity of 2.
    • For a non-periodic spline, the first and last knots always have a multiplicity of 4.
    • If the points just before and just after have multiplicities >=3, the piece between these two is fully continuous, and this (middle) point will only be constrained with point-on-object. If a knot is needed, consider using the insert knot tool.