Sketcher CreateEllipseByCenter

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Sketcher CreateEllipseByCenter

Menu location
Sketch → Sketcher geometries → Create ellipse by center
Workbenches
Sketcher
Default shortcut
G E E
Introduced in version
0.15
See also
Sketcher Ellipse by 3 Points, Sketcher Circle, Sketcher Arc of Ellipse

Description

The Sketcher CreateEllipseByCenter tool creates an ellipse by its center, an endpoint of its major axis, and a point along the ellipse or an endpoint of its minor axis. introduced in version 0.22: Or optionally by the endpoints of its major axis and a point along the ellipse.

Usage

See also: Drawing aids.

Pos-OVP = Positional On-View-Parameters. introduced in version 0.22
Dim-OVP = Dimensional On-View-Parameters. introduced in version 0.22

  1. There are several ways to invoke the tool:
    • Press the Ellipse by center, major radius, point button.
    • Select the Sketcher → Sketcher geometries → Create Ellipse by center option from the menu.
    • Use the keyboard shortcut: G then E, then E.
  2. The cursor changes to a white cross with the current tool mode icon.
  3. The Ellipse parameters section (introduced in version 0.22) is added at the top of the Sketcher Dialog.
  4. Optionally press the M key or select from the dropdown list in the parameters section to change the tool mode:
    • Center:
      1. Pick the center of the ellipse. Or with Pos-OVP: enter its X and/or Y coordinate.
      2. Pick an endpoint of the major axis. Or with Dim-OVP: enter the distance from the center to this endpoint and/or the angle of the major axis.
      3. Pick a point to define the radii of the ellipse. Or with Dim-OVP: enter the distance from the center to an endpoint of its minor axis.
    • Axis endpoints and radius: introduced in version 0.22
      1. Pick the endpoints of the major axis of the ellipse. Or with Pos-OVP: enter their X and/or Y coordinates. No constraints are created for these points.
      2. Pick a point to define the radii of the ellipse. Or with Pos-OVP: enter its X and/or Y coordinate. No constraint is created for this point.
  5. The geometry is created, including a set of internal alignment geometry elements (major axis, minor axis and two foci), and applicable Pos-OVP and Dim-OVP based constraints are added.
  6. Optionally deleted the internal geometry. It can be recreated at any time with Sketcher RestoreInternalAlignmentGeometry.

Peculiarities

  • Major and minor axes of ellipses are strict and cannot be swapped by resizing the ellipse. This is a consequence of the solver parametrization used (center (x,y), focus1 (x,y) and minor radius length (b)) and the same strict behavior of OpenCascade. The ellipse must be rotated to swap the axes.
  • Ellipse can function as a circle when its major and minor diameter lines are deleted, and one of the foci is constrained to coincide with the center. But radius constraint won't work on such a circle.
  • Moving the ellipse by edge is the same as moving ellipse's center.