Vazba Bod na bod
Constraint PointOnPoint |
Umístění Menu |
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Sketch → Sketcher constraints → Constrain coincident |
Pracovní stoly |
Náčrt |
Výchozí zástupce |
C |
Představen ve verzi |
- |
Viz také |
Constraint Lock, Vazba Bod na objekt |
Description
Popis
Vytváří vazbu totožnosti na vybrané položce.
Tento vazbový nástroj vezme dva body jako své argumenty a slouží k tomu, že je udělá totožné. (Znamená to, že je udělá jako-jeden-bod).
V praxi je tento nástroj užitečný když je např. mezera mezi dvěma koncovými body přímek, které mají být spojeny - vazba totožnosti na jejich koncové body tuto mezeru uzavře.
Usage
Použití
Jak je uvedeno výše, tento nástroj přijímá dva argumenty - oba jsou to body.
- Nejdříve je nutné vysvítit dva různé body. (Připomínám, že to nebude fungovat jestli se např. pokusíte vybrat počáteční a koncový bod jedné přímky).
- Vysvícení nakreslených položek dosáhnete posunem myši nad položku a kliknutím levým tlačítkem myši.
- Vysvícená položka změní barvu na zelenou.
- následující položky mohou být vysvíceny opakováním výše uvedeného postupu POZNÁMKA: není potřeba zároveň držet stisknutou nějakou další klávesu, jako např. CTRL, abychom dosáhli vícenásobného výběru položek na výkrese.
- Jakmile máte vybrány dva body, kliknutím levým tlačítkem myši na vazbu 'BodNaBod' zajistí, že se body stanou totožné a jsou nahrazeny jedním bodem.
POZNÁMKA: Kvůli nastavení totožnosti bodů, musí FreeCAD nutně posunout jeden nebo oba původní body.
Note: In order to make two points coincident, FreeCAD must out of necessity move one (or both) of the original points.
Scripting
General 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 objectLineFixed
is the number of the line, that will not move by applying the constraintPointOfLineFixed
is the number of the vertex of the lineLineFixed
that has to fulfilled the constraintLineMoving
is the number of the line, that will move by applying the constraintPointOfLineMoving
is the number of the lineLineMoving
, that has to fulfilled the 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.
The next paragraph will explain you how to identify the numbering of a line and of a vertex of a line.
Identifying the numbering of a line
I have drawn three lines as shown in the following figure.
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.
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
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.
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.
blue text: numbering of line, black text: numbering of vertices
The command Sketch.addConstraint(Sketcher.Constraint('Coincident',1,2,2,1))
yields following result:
The command Sketch.addConstraint(Sketcher.Constraint('Coincident',0,2,2,2))
yields following result:
- Getting started
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- Sketcher constraints:
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- Geometric constraints: Coincident (unified), Coincident, Point on object, Horizontal/vertical, Horizontal, Vertical, Parallel, Perpendicular, Tangent or collinear, Equal, Symmetric, Block
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- Additional: Sketcher Dialog, Preferences, Sketcher scripting