Sketcher: Vincolo Coincidenza di punti

From FreeCAD Documentation
This page is a translated version of the page Sketcher ConstrainCoincident and the translation is 19% complete.
Outdated translations are marked like this.

Coincidenza

Posizione nel menu
Sketch → Vincoli → Coincidenza
Ambiente
Schizzo
Avvio veloce
C
Introdotto nella versione
-
Vedere anche
Blocca, Punto su oggetto

Descrizione

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.

Utilizzo

  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.

Script generico

Il vincolo può essere creato dalle macro e dalla console python utilizzando il seguente comando:

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))

dove:

  • Sketch è un oggetto schizzo.
  • LineFixed è il numero della linea, che non deve muoversi applicando il vincolo.
  • PointOfLineFixed è il numero del vertice della linea LineFixed che deve soddisfare il vincolo.
  • LineMoving è il numero della linea che si sposterà applicando il vincolo.
  • PointOfLineMoving è il numero della linea LineMoving che deve soddisfare il vincolo.

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.