Sketcher ConstrainCoincident/pt: Difference between revisions

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<languages/>
{{GuiCommand/pt|Name=Constraint PointOnPoint|Name/pt=Constraint PointOnPoint|Workbenches=[[Sketcher Workbench/pt|Sketcher]], [[PartDesign Workbench/pt|PartDesign]]|MenuLocation=Sketch → Sketcher constraints → Constrain coincident|SeeAlso=[[Constraint Lock/pt|Constraint Lock]], [[Constraint PointOnObject/pt|Constraint Point onto Object]]}}


{{Docnav
==Description==
|[[Sketcher_ConstrainCoincidentUnified|Coincident (unified)]]
Create a coincident constraint on the selected item
|[[Sketcher_ConstrainPointOnObject|Point on object]]
|[[Sketcher_Workbench|Sketcher]]
|IconL=Sketcher_ConstrainCoincidentUnified.svg
|IconR=Constraint_PointOnObject.svg
|IconC=Workbench_Sketcher.svg
}}


<div class="mw-translate-fuzzy">
This constraint tool takes two points as its argument and serves to make the two points ''coincident''. (Meaning to make them as-one-point).
{{GuiCommand/pt
|Icon=Constraint PointOnPoint.svg
|Name/pt=Sketcher ConstrainCoincident
|Workbenches=[[Sketcher Workbench/pt|Sketcher]]
|MenuLocation=Sketch → Sketcher constraints → Constrain coincident
|SeeAlso=[[Sketcher_ConstrainLock/pt|Constrain Lock]], [[Sketcher ConstrainPointOnObject/pt|Constrain Point onto Object]]
}}
</div>


==Description==
In practical terms this constraint tool is useful when there is a break in a profile for example - where two lines end near each other and need to be joined - a coincident constraint on their end-points will close the gap.


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).
==How to Use==
As stated above, this tool takes two arguments - both are points.
#Firstly it is necessary to highlight two distinct points. (Note this will not work if, for example, you attempt to select the start and end point of the same line).
#Highlighting of a drawing item is achieved by moving the mouse over the item and clicking the left-mouse-button.
#A highlighted item will change colour to green.
#Subsequent items can be highlighted by repeating the above procedure(s) NOTE: There is no-need to hold-down any special key like Ctrl to achieve multiple item selection in a drawing.
#Once you have two points highlighted, left-clicking on the 'PointOnPoint' [[Image:Constraint_PointOnPoint.png|32px]] constraint will cause the two points to become ''coincident'' and be replaced by a single point.


{{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]].
NOTE: In order to make two points coincident, FreeCAD must necessarily move one, or both, of the original points.


==Scripting==
==Usage==


# Optionally do one of the following:
===General scripting===
#* Select two or more points.
The constraint can be created from macros and from the python console by using the following command:
#* Select two or more edges of circles, arcs, ellipses or arcs of ellipses.
{{Code|code=Sketch.addConstraint(Sketcher.Constraint('Coincident',LineFixed,PointOfLineFixed,LineMoving,PointOfLineMoving)) }}
# There are several ways to invoke the command:
where :
#* Press the {{Button|[[Image:Sketcher_ConstrainCoincident.svg|16px]] [[Sketcher_ConstrainCoincident|Constrain coincident]]}} button.
*Sketch is a sketch object
#* Select the {{MenuCommand|Sketch → Sketcher constraints → [[Image:Sketcher_ConstrainCoincident.svg|16px]] Constrain coincident}} option from the menu.
*LineFixed is the number of the line, that will not move by applying the constraint
#* Use the keyboard shortcut: {{KEY|C}}.
*PointOfLineFixed is the number of the vertex of the line LineFixed that has to fulfilled the constraint
# To indicate that the command has been activated the cursor changes to a white cross with the command icon.
*LineMoving is the number of the line, that will move by applying the constraint
# Optionally keep selecting elements. You can only select two elements at a time now.
*PointOfLineMoving is the number of the line LineMoving, that has to fulfilled the constraint
# To finish the command press {{KEY|Esc}} or the right mouse button, or start a another constraints or geometries command.


== Alternatives to Coincident constraint ==
The main issue by using this function is to identify correctly the line number and the vertex number of the lines you want to process.


Some combinations which are not possible with a coincident constraint can be emulated using other constraints:
The next paragraph will explain you how to identify the numbering of a line and of a vertex of a 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|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|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|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.


==Scripting==
===Identifying the numbering of a line===


The constraint can be created from [[Macros|macros]] and from the [[Python|Python]] console by using the following command:
I have drawn three lines as shown in the following figure.


{{Code|code=Sketch.addConstraint(Sketcher.Constraint('Coincident',LineFixed,PointOfLineFixed,LineMoving,PointOfLineMoving)) }}
[[File:PartDesignConstraintPointOnPointScriptingFigure1.jpg|600px]]


where :
By moving the cursor of the mouse above the line you can see the line number at the bottom left of the FreeCAD windows, see next figure.
* {{incode|Sketch}} is a sketch object
* {{incode|LineFixed}} is the number of the line, that will not move by applying the constraint
* {{incode|PointOfLineFixed}} indicates which vertex of {{incode|LineFixed}} has to fulfill the constraint
* {{incode|LineMoving}} is the number of the line, that will move by applying the constraint
* {{incode|PointOfLineMoving}} indicates which vertex of {{incode|LineMoving}} has to fulfill the constraint


As the names {{incode|LineFixed}} and {{incode|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.
[[File:PartDesignConstraintPointOnPointScriptingFigure2.jpg|600px]]


The [[Sketcher_scripting|Sketcher scripting]] page explains the values which can be used for {{incode|LineFixed}}, {{incode|PointOfLineFixed}}, {{incode|LineMoving}} and {{incode|PointOfLineMoving}}, and contains further examples on how to create constraints from Python scripts.
Unfortunately the numbering displayed on the FreeCAD windows start from 1 whereas the numbering of the line used to script start from 0: this means that you have to retrieve one each time you want to refer to a line.


===Identifying the numbering of the vertices of a line===


<div class="mw-translate-fuzzy">
The vertices of one line can only have the value 1 or 2. (Don’t ask me, why the vertices numbering does not start from 0 …) The vertices are numbered according to their order of creation. To find out the order of their creation (If you have a lot of lines, you cannot remember which vertex you have created first), you just have to move the cursor of your mouse above the two vertices of one line, see following figure.
[[Category:Sketcher/pt]]
</div>


{{Sketcher_Tools_navi{{#translation:}}}}
[[File:PartDesignConstraintPointOnPointScriptingFigure3.jpg|600px]]
{{Userdocnavi{{#translation:}}}}

If you read e.g. 4 and 5, it means that the vertex 4 will be referenced by using the number 1 in the script command and the vertex 5 will be referenced by using the number 2 in the script command. Etc.

=== Example ===

Let us take the previous example of the three lines. The subsequent figure indicates the numbering of each line and their vertices according to the convention for scripting.

[[File:PartDesignConstraintPointOnPointScriptingFigure3Bis.jpg|600px]]

blue text = numbering of line, black text = numbering of vertices

The command
{{Code|code= Sketch.addConstraint(Sketcher.Constraint('Coincident',1,2,2,1)) }}
yields following result:

[[File:PartDesignConstraintPointOnPointScriptingFigure4.jpg|600px]]

The command
{{Code|code= Sketch.addConstraint(Sketcher.Constraint('Coincident',0,2,2,2)) }}
yields following result:

[[File:PartDesignConstraintPointOnPointScriptingFigure5.jpg|600px]]


{{clear}}
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Revision as of 13:58, 17 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 changes 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.