Sketcher ConstrainCoincident/pt: Difference between revisions

From FreeCAD Documentation
(Updating to match new version of source page)
(Updating to match new version of source page)
Line 22: Line 22:
==Description==
==Description==


Affixes a point onto (coincident with) one or more other points. {{Version|0.21}}: It acts as a concentric constraint if two or more circles, arcs, ellipses or arcs of ellipses are selected.
The [[Image:Sketcher_ConstrainCoincident.svg|24px]] [[Sketcher_ConstrainCoincident|Sketcher ConstrainCoincident]] command creates a coincident constraint between points, or ({{Version|0.21}}) a concentric constraint between circles, arcs and/or ellipses (by making their centers coincident).

{{Version|0.22}}: This command is replaced by the [[Sketcher_ConstrainCoincidentUnified|Sketcher ConstrainCoincidentUnified]] command if the {{MenuCommand|Unify Coincident and PointOnObject}} option is selected in the [[Sketcher_Preferences#General|Sketcher Preferences]].


==Usage==
==Usage==


# Do one of the following:
# Optionally do one of the following:
#* Select two or more points.
#* Select two or more points.
#* Select two or more edges of circles, arcs, ellipses or arcs of ellipses.
#* Select two or more edges of circles, arcs, ellipses or arcs of ellipses.
# There are several ways to invoke the command:
# There are several ways to invoke the command:
#* Press the {{Button|[[File:Sketcher_ConstrainCoincident.svg|16px]] [[Sketcher_ConstrainCoincident|Constrain coincident]]}} button in the toolbar.
#* Press the {{Button|[[Image:Sketcher_ConstrainCoincident.svg|16px]] [[Sketcher_ConstrainCoincident|Constrain coincident]]}} button.
#* Select the {{MenuCommand|Sketch → Sketcher constraints → [[Image:Sketcher_ConstrainCoincident.svg|16px]] Constrain coincident}} option from the menu.
#* Use the {{KEY|C}} keyboard shortcut.
#* Use the keyboard shortcut: {{KEY|C}}.
#* Use the {{MenuCommand|Sketch → Sketcher constraints → [[File:Sketcher_ConstrainCoincident.svg|16px]] Constrain coincident}} entry in the top menu.
# To indicate that the command has been activated the cursor changed to a white cross with the command icon.
# Optionally keep selecting elements. You can only select two elements at a time now.
# To finish the command press {{KEY|Esc}} or the right mouse button, or start a another constraints or geometries command.


== Alternatives to Coincident constraint ==
== Alternatives to Coincident constraint ==


The two constrained items of a [[Sketcher_ConstrainCoincident|Coincident]] constraint must be start point or end point vertices, or center points of arcs, circles or ellipses. Some combinations which are not possible with a coincident constraint can be emulated using other constraints:
Some combinations which are not possible with a coincident constraint can be emulated using other constraints:
* The [[File:Sketcher_ConstrainSymmetric.svg|24px]] [[Sketcher_ConstrainSymmetric|Symmetric]] constraint can be used to place a start point, end point or center point on the midpoint of a straight line.
* The [[File:Sketcher_ConstrainSymmetric.svg|16px]] [[Sketcher_ConstrainSymmetric|Symmetric]] constraint can be used to place a start point, end point or center point on the midpoint of a straight line.
* A midpoint-to-midpoint placement of two straight lines can be achieved by creating a new [[File:Sketcher_CreatePoint.svg|24px]] [[Sketcher_CreatePoint|Point]] and using two [[File:Sketcher_ConstrainSymmetric.svg|24px]] [[Sketcher_ConstrainSymmetric|Symmetric]] constraints so that it lies on the midpoint of both lines.
* A midpoint-to-midpoint placement of two straight lines can be achieved by creating a new [[File:Sketcher_CreatePoint.svg|16px]] [[Sketcher_CreatePoint|Point]] and using two [[File:Sketcher_ConstrainSymmetric.svg|16px]] [[Sketcher_ConstrainSymmetric|Symmetric]] constraints so that it lies on the midpoint of both lines.
* A vertex can be constrained to lie along an edge using a [[File:Sketcher_ConstrainPointOnObject.svg|24px]][[Sketcher_ConstrainPointOnObject|PointOnObject]] constraint. Note that with this constraint, the point can lie anywhere on the full extension of a segment or curve (i.e. also before the start point or beyond the end point).
* A vertex can be constrained to lie along an edge using a [[File:Sketcher_ConstrainPointOnObject.svg|16px]] [[Sketcher_ConstrainPointOnObject|PointOnObject]] constraint. Note that with this constraint, the point can lie anywhere on the full extension of a segment or curve (i.e. also before the start point or beyond the end point).
* A collinear placement of two straight lines can be obtained by applying a [[File:Sketcher_ConstrainTangent.svg|24px]] [[Sketcher_ConstrainTangent|Tangent]] constraint to them, or by combining a [[File:Sketcher_ConstrainPointOnObject.svg|24px]] [[Sketcher_ConstrainPointOnObject|PointOnObject]] constraint and a [[File:Sketcher_ConstrainParallel.svg|24px]] [[Sketcher_ConstrainParallel|Parallel]] constraint.
* A collinear placement of two straight lines can be obtained by applying a [[File:Sketcher_ConstrainTangent.svg|16px]] [[Sketcher_ConstrainTangent|Tangent]] constraint to them, or by combining a [[File:Sketcher_ConstrainPointOnObject.svg|16px]] [[Sketcher_ConstrainPointOnObject|PointOnObject]] constraint and a [[File:Sketcher_ConstrainParallel.svg|16px]] [[Sketcher_ConstrainParallel|Parallel]] constraint.
* Two edges can be made identical by using two [[File:Sketcher_ConstrainCoincident.svg|24px]] [[Sketcher_ConstrainCoincident|Coincident]] constraints, one for each pair of extremities.
* Two circles can be made identical by using a [[File:Sketcher_ConstrainCoincident.svg|24px]] [[Sketcher_ConstrainCoincident|Coincident]] constraint to merge the centers, and applying an [[File:Sketcher_ConstrainEqual.svg|24px]] [[Sketcher_ConstrainEqual|Equal]] constraint to their edges. For arcs, this will ensure both arcs are part of the same circle, while allowing them to have different start and end points.


==Scripting==
==Scripting==

Revision as of 16:50, 15 January 2024

Sketcher ConstrainCoincident

Localização do menu
Sketch → Sketcher constraints → Constrain coincident
Bancadas de trabalho
Sketcher
Atalho padrão
Nenhum
Introduzido na versão
-
Veja também
Constrain Lock, Constrain Point onto Object

Description

The Sketcher ConstrainCoincident command creates a coincident constraint between points, or (introduced in version 0.21) a concentric constraint between circles, arcs and/or ellipses (by making their centers coincident).

introduced in version 0.22: This command is replaced by the Sketcher ConstrainCoincidentUnified command if the Unify Coincident and PointOnObject option is selected in the Sketcher Preferences.

Usage

  1. Optionally do one of the following:
    • Select two or more points.
    • Select two or more edges of circles, arcs, ellipses or arcs of ellipses.
  2. There are several ways to invoke the command:
    • Press the Constrain coincident button.
    • Select the Sketch → Sketcher constraints → Constrain coincident option from the menu.
    • Use the keyboard shortcut: C.
  3. To indicate that the command has been activated the cursor changed to a white cross with the command icon.
  4. Optionally keep selecting elements. You can only select two elements at a time now.
  5. To finish the command press Esc or the right mouse button, or start a another constraints or geometries command.

Alternatives to Coincident constraint

Some combinations which are not possible with a coincident constraint can be emulated using other constraints:

  • The Symmetric constraint can be used to place a start point, end point or center point on the midpoint of a straight line.
  • A midpoint-to-midpoint placement of two straight lines can be achieved by creating a new Point and using two Symmetric constraints so that it lies on the midpoint of both lines.
  • A vertex can be constrained to lie along an edge using a PointOnObject constraint. Note that with this constraint, the point can lie anywhere on the full extension of a segment or curve (i.e. also before the start point or beyond the end point).
  • A collinear placement of two straight lines can be obtained by applying a Tangent constraint to them, or by combining a PointOnObject constraint and a Parallel constraint.

Scripting

The constraint can be created from macros and from the Python console by using the following command:

Sketch.addConstraint(Sketcher.Constraint('Coincident',LineFixed,PointOfLineFixed,LineMoving,PointOfLineMoving))

where :

  • Sketch is a sketch object
  • LineFixed is the number of the line, that will not move by applying the constraint
  • PointOfLineFixed indicates which vertex of LineFixed has to fulfill the constraint
  • LineMoving is the number of the line, that will move by applying the constraint
  • PointOfLineMoving indicates which vertex of LineMoving has to fulfill the constraint

As the names LineFixed and LineMoving indicate, if both constrained vertices are free to move in any direction, the first one (first to be selected in the Gui) will remain fixed and the other one will move. In the presence of existing constraints, however, both edges may move.

The Sketcher scripting page explains the values which can be used for LineFixed, PointOfLineFixed, LineMoving and PointOfLineMoving, and contains further examples on how to create constraints from Python scripts.