Sketcher CreateEllipseBy3Points
Sketcher CreateEllipseBy3Points |
Menu location |
---|
Sketch → Sketcher geometries → Create ellipse by 3 points |
Workbenches |
Sketcher |
Default shortcut |
G 3 E |
Introduced in version |
0.15 |
See also |
Sketcher Ellipse by center, Sketcher Circle, Sketcher Arc of Ellipse |
Description
The Sketcher CreateEllipseBy3Points tool creates an ellipse by three points: the endpoints of the major axis (periapsis and apoapsis) and one point on the ellipse outline to define the minor radius. introduced in version 0.22: Or optionally by its center, the end point of the major radius, and the minor radius, see Sketcher CreateEllipseByCenter).
The sequence of clicks is indicated by yellow arrows with numbers.
1 is the periapsis, 2 is the apoapsis, 3 is the point defining the minor diameter,
a is the major diameter, b is the minor diameter (green lines),
c is the ellipse center and f are the focal points.
The blue lines are construction lines for illustration purposes.
Usage
- There are several ways to invoke the command:
- Press the Ellipse by periapsis, apoapsis, minor radius button.
- Select the Sketcher → Sketcher geometries → Create Ellipse by 3 points option from the menu.
- The keyboard shortcut: G then 3, E.
- The cursor changes to a white cross with the command icon.
- The Ellipse parameters section (introduced in version 0.22) is added at the top of the Sketcher Dialog.
- Optionally press the M key or select from the dropdown list in the parameters section to change the tool Mode:
- Axis endpoints and radius:
- Pick two points to define the major axis. Or with Pos-OVP: enter their X and/or Y coordinates.
- Pick a point on outline of the ellipse to define the minor radius. Or with Pos-OVP: enter its X and/or Y coordinates.
- Center: introduced in version 0.22
- Pick the center of the ellipse. Or with Pos-OVP: enter its X and/or Y coordinate.
- Pick a point to set the major radius, and the orientation of the major axis. Or with Dim-OVP: enter the major radius of the ellipse and the angle of the major axis.
- Pick a point on the outline of the ellipse to define the minor radius. Or with Pos-OVP: enter the minor radius.
- Axis endpoints and radius:
- The geometry is created and applicable Pos-OVP and Dim-OVP based constraints are added (none for Axis endpoints and radius). A set of internal geometry aligned to it (major diameter, minor diameter, two foci) is also created. The internal geometry can be manually deleted if not needed, and recreated later. See Sketcher Show Hide Internal Geometry.
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.
Sketcher
- General: Create sketch, Edit sketch, Map sketch to face, Reorient sketch, Validate sketch, Merge sketches, Mirror sketch, Leave sketch, View sketch, View section, Toggle grid, Toggle snap, Configure rendering order, Stop operation
- Sketcher geometries: Point, Line, Arc, Arc by 3 points, Circle, Circle by 3 points, Ellipse, Ellipse by 3 points, Arc of ellipse, Arc of hyperbola, Arc of parabola, B-spline by control points, Periodic B-spline by control points, B-spline by knots, Periodic B-spline by knots, Polyline, Rectangle, Centered rectangle, Rounded rectangle, Triangle, Square, Pentagon, Hexagon, Heptagon, Octagon, Regular polygon, Slot, Fillet, Corner-preserving fillet, Trim, Extend, Split, External geometry, Carbon copy, Toggle construction geometry
- Sketcher constraints:
- Geometric constraints: Coincident, Point on object, Vertical, Horizontal, Parallel, Perpendicular, Tangent, Equal, Symmetric, Block
- Dimensional constraints: Lock, Horizontal distance, Vertical distance, Distance, Radius or weight, Diameter, Auto radius/diameter, Angle, Refraction (Snell's law)
- Constraint tools: Toggle driving/reference constraint, Activate/deactivate constraint
- Sketcher tools: Select unconstrained DoF, Select associated constraints, Select associated geometry, Select redundant constraints, Select conflicting constraints, Show/hide internal geometry, Select origin, Select horizontal axis, Select vertical axis, Symmetry, Clone, Copy, Move, Rectangular array, Remove axes alignment, Delete all geometry, Delete all constraints
- Sketcher B-spline tools: Show/hide B-spline degree, Show/hide B-spline control polygon, Show/hide B-spline curvature comb, Show/hide B-spline knot multiplicity, Show/hide B-spline control point weight, Convert geometry to B-spline, Increase B-spline degree, Decrease B-spline degree, Increase knot multiplicity, Decrease knot multiplicity, Insert knot, Join curves
- Sketcher virtual space: Switch virtual space
- Additional: Sketcher Dialog, Preferences, Sketcher scripting
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