Donate

Circle by 3 points

Ellipse by 3 points

Sketcher

Description

The Sketcher CreateEllipseByCenter tool creates an ellipse by its center, an endpoint of one of its axes, and a point along the ellipse. introduced in 1.0: Or optionally by both endpoints of one of its axes and a point along the ellipse.

Ellipse (white) with internal geometry (dark yellow)

Usage

See also: Drawing aids.

Pos-OVP = Positional On-View-Parameters. introduced in 1.0
Dim-OVP = Dimensional On-View-Parameters. introduced in 1.0

1. There are several ways to invoke the tool:
   • Press the Ellipse by center, radius, rim 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 cross with the current tool mode icon.
3. The Ellipse parameters section (introduced in 1.0) 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 one of the axes of the ellipse, this also defines one of its radii. Or with Dim-OVP: enter this radius and/or the angle of this axis.
     3. Pick a point to define the other radius of the ellipse. Or with Dim-OVP: enter this radius.
   • Axis endpoints: introduced in 1.0
     1. Pick the endpoints of one of the axes of the ellipse, this also defines one of its radii. 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 other radius of the ellipse. Or with Pos-OVP: enter its X and/or Y coordinate. No constraint is created for this point.
5. The ellipse is created, including a set of internal geometry (major axis, minor axis and two foci), and applicable Pos-OVP and Dim-OVP based constraints are added.
6. If the tool runs in continue mode:
   1. Optionally keep creating ellipses.
   2. To finish, right-click or press Esc, or start another geometry or constraint creation tool.

Notes

• Elements of the internal geometry can be deleted. They can be recreated at any time with Sketcher RestoreInternalAlignmentGeometry.
• Once created, the major and minor axes of an ellipse are strict and cannot be swapped by resizing. This is a consequence of the solver parametrization and the same strict behavior of OpenCASCADE. An ellipse must be rotated to swap its axes.

Circle by 3 points

Ellipse by 3 points

Sketcher