Sketcher ConstrainAngle: Difference between revisions

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The constraint sets the polar angle of line's direction. It is the angle between the line and X axis of the sketch.
The angle of the line with the positive X axis of the sketch is fixed.


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The aperture angle of the arc is fixed.
In this mode, the constraint fixes angular span of a circular arc.


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In this mode, the constraint sets the angle between two lines. It is not required that the lines intersect.
The angle between the two lines is fixed. It is not required that the lines intersect.


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===Between two edges at point (angle-via-point)=== <!--T:35-->
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The angle between the two edges at a given point is fixed. The point can be any point, e.g. the center of a circle, the endpoint of an edge, or the origin, it can belong to one of the edges, and it can also be a [[Sketcher_CreatePoint|point object]]. If required [[Sketcher_ConstrainPointOnObject|point onto object constraint(s)]] are added to ensure the point lies on (the extension of) both edges.
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In this mode, angle between two curves is constrained at the point of their intersection. The intersection point can be on curves' extensions. The point should be specified explicitly, since curves typically intersect in more than one point.

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For the constraint to work correctly, the point must be on both curves. So, as the constraint is invoked, the point will be automatically constrained onto both curves ([[Sketcher_helper_constraint|helper constraints]] will be added, if necessary), and the angle between curves will be constrained at the point. These [[Sketcher_helper_constraint|helper constraints]] are plain regular constraints. They can be added manually, or deleted. There are no helper constraints on the example picture above, because the point selected is already the intersection of curves.


==Scripting== <!--T:21-->
==Scripting== <!--T:21-->

Revision as of 18:33, 8 March 2024

This documentation is a work in progress. Please don't mark it as translatable since it will change in the next hours and days.

Sketcher ConstrainAngle

Menu location
Sketch → Sketcher constraints → Constrain angle
Workbenches
Sketcher
Default shortcut
K A
Introduced in version
-
See also
Sketcher Constrain distance, Sketcher Constraint Perpendicular

Description

The Sketcher ConstrainAngle tool is a datum constraint intended to fix angles in a sketch. It is capable of setting slopes of individual lines, angles between lines, angles of intersections of curves, and angle spans of circular arcs. Lines are treated as infinite, and arcs are treated as full circles/ellipses.

Usage

See also: Drawing aids.

Continue mode

  1. Make sure there is no selection.
  2. There are several ways to invoke the tool:
    • introduced in version 0.22: If the Dimensioning constraints preference is set to Single tool (default): press the down arrow to the right of the button and select the Constrain angle option from the dropdown.
    • If this preference has a different value (and in version 0.21 and below): press the Constrain angle button.
    • Select the Sketch → Sketcher constraints → Constrain angle option from the menu.
    • introduced in version 0.22: Right-click in the 3D view and select the Dimension → Constrain angle option from the context menu.
    • Use the keyboard shortcut: K then A.
  3. The cursor changes to a white cross with the tool icon.
  4. Do one of the following:
    • Select two lines.
    • Select a point and two edges (in that order).
    • Select an edge, a point and an edge (idem).
  5. If a driving constraint is created, and the Ask for value after creating a dimensional constraint preference is selected (default):
    1. A dialog opens to edit the constraint value.
    2. Press the OK button to confirm.
  6. A constraint is added.
  7. Optionally keep creating constraints.
  8. To finish, right-click or press Esc, or start another geometry or constraint creation tool.

Once-only mode

  1. Do one of the following:
    • Select a single line.
    • Select a single arc.
    • Select two lines.
    • Select a point and two edges (in any order).
  2. Invoke the tool as explained above.
  3. Edit and/or confirm the constraint value as explained above.
  4. A constraint is added.

Examples

Single line

The angle of the line with the positive X axis of the sketch is fixed.

Single circular arc

The aperture angle of the arc is fixed.

Between two lines

The angle between the two lines is fixed. It is not required that the lines intersect.

Between two edges at point (angle-via-point)

The angle between the two edges at a given point is fixed. The point can be any point, e.g. the center of a circle, the endpoint of an edge, or the origin, it can belong to one of the edges, and it can also be a point object. If required point onto object constraint(s) are added to ensure the point lies on (the extension of) both edges.

Scripting

Angle Constraint can be created from macros and from the Python console by using the following:

# line slope angle
Sketch.addConstraint(Sketcher.Constraint('Angle',iline,angle))

# angular span of arc
Sketch.addConstraint(Sketcher.Constraint('Angle',iarc,angle))

# angle between lines
Sketch.addConstraint(Sketcher.Constraint('Angle',iline1,pointpos1,iline2,pointpos2,angle))

# angle-via-point (no helper constraints are added automatically when from python)
Sketch.addConstraint(Sketcher.Constraint('AngleViaPoint',icurve1,icurve2,geoidpoint,pointpos,angle))

where:

  • Sketch is a sketch object
  • iline, iline1, iline2 are integers specifying the lines by their ordinal numbers in Sketch.
  • pointpos1, pointpos2 should be 1 for start point and 2 for end point. The choice of endpoints allows to set internal angle (or external), and it affects how the constraint is drawn on the screen.
  • geoidpoint and pointpos in AngleViaPoint are the indexes specifying the point of intersection.
  • angle is the angle value in radians. The angle is counted between tangent vectors in counterclockwise direction. Tangent vectors are pointing from start to end for the lines (or vice versa if ending point is supplied in angle between lines mode), and along counterclockwise direction for circles, arcs and ellipses. Quantity is also accepted as an angle (e.g. App.Units.Quantity('45 deg'))

The Sketcher scripting page explains the values which can be used for iline, iline1, iline2, pointpos1, pointpos2, geoidpoint and pointpos and contains further examples on how to create constraints from Python scripts.