Sketcher CreateBSplineByInterpolation
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Sketcher CreateBSplineByInterpolation |
Menu location |
---|
Sketch → Sketcher geometries → Create B-spline by knots |
Workbenches |
Sketcher |
Default shortcut |
G B I |
Introduced in version |
0.21 |
See also |
Sketcher Periodic B-spline |
Description
The Sketcher CreateBSplineByInterpolation tool creates a B-spline curve passing through given points. See this page for more info about B-splines.
Usage
- There are several ways to invoke the tool:
- Press the B-spline by knots button.
- Select the Sketcher → Sketcher geometries → Create B-spline by knots option from the menu.
- Use the keyboard shortcut: G then B, then I.
- The cursor changes to a white cross with the tool icon.
- Pick several knot points.
- Optionally press M before terminating the input to define the multiplicity of the last defined knot point (note that this may not always be respected, see limitations for details).
- Optionally press Backspace before terminating the input to delete the last knot point.
- Right-click or press Esc to terminate the input.
- The B-spline is created, including a set of internal geometry (weight circles and knot points)...
- Optionally deleted one or more elements of this internal geometry. They can be recreated at any time with Sketcher RestoreInternalAlignmentGeometry...
Notes
Limitations
- The resultant curve is no different from a (non-uniform) B-spline defined through control points. So all related limitations apply. See Sketcher CreateBSpline.
- The created B-splines are always cubic (i.e. with degree 3).
- The defined multiplicity may not always be respected:
- For a periodic spline, the first knot (coincident with last) always has a multiplicity of 2.
- For a non-periodic spline, the first and last knots always have a multiplicity of 4.
- If the points just before and just after have multiplicities >=3, the piece between these two is fully continuous, and this (middle) point will only be constrained with point-on-object. If a knot is needed, consider using the insert knot tool.
Sketcher
- General: Create sketch, Edit sketch, Attach sketch, 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, Polyline, Line, Arc, Arc by 3 points, Arc of ellipse, Arc of hyperbola, Arc of parabola, Circle, Circle by 3 points, Ellipse, Ellipse by 3 points, Rectangle, Centered rectangle, Rounded rectangle, Triangle, Square, Pentagon, Hexagon, Heptagon, Octagon, Regular polygon, Slot, Arc slot, B-spline by control points, Periodic B-spline by control points, B-spline by knots, Periodic B-spline by knots, Toggle construction geometry
- Sketcher constraints:
- Dimensional constraints: Dimension, Horizontal distance, Vertical distance, Distance, Auto radius/diameter, Radius, Diameter, Angle, Lock
- Geometric constraints: Coincident (unified), Coincident, Point on object, Horizontal/vertical, Horizontal, Vertical, Parallel, Perpendicular, Tangent or collinear, Equal, Symmetric, Block
- Other constraints: Refraction (Snell's law)
- Constraint tools: Toggle driving/reference constraint, Activate/deactivate constraint
- Sketcher tools: Fillet, Chamfer, Trim, Split, Extend, External geometry, Carbon copy, Select origin, Select horizontal axis, Select vertical axis, Array transform, Polar transform, Scale transform, Offset geometry, Symmetry, Remove axes alignment, Delete all geometry, Delete all constraints
- Sketcher B-spline tools: Convert geometry to B-spline, Increase B-spline degree, Decrease B-spline degree, Increase knot multiplicity, Decrease knot multiplicity, Insert knot, Join curves
- Sketcher visual: Select unconstrained DoF, Select associated constraints, Select associated geometry, Select redundant constraints, Select conflicting constraints, Show/hide circular helper for arcs, 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, Show/hide internal geometry, Switch virtual space
- Additional: Sketcher Dialog, Preferences, Sketcher scripting
User documentation
- Getting started
- Installation: Download, Windows, Linux, Mac, Additional components, Docker, AppImage, Ubuntu Snap
- Basics: About FreeCAD, Interface, Mouse navigation, Selection methods, Object name, Preferences, Workbenches, Document structure, Properties, Help FreeCAD, Donate
- Help: Tutorials, Video tutorials
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- Hubs: User hub, Power users hub, Developer hub