Sketcher BSplineDecreaseDegree/pt-br: Difference between revisions
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{{Docnav |
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|[[Sketcher_BSplineIncreaseDegree|Increase B-spline degree]] |
|[[Sketcher_BSplineIncreaseDegree|Increase B-spline degree]] |
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{{GuiCommand |
{{GuiCommand |
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|Name=Sketcher BSplineDecreaseDegree |
|Name=Sketcher BSplineDecreaseDegree |
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|MenuLocation=Sketch → Sketcher B-spline tools → Decrease |
|MenuLocation=Sketch → Sketcher B-spline tools → Decrease B-spline degree |
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|Workbenches=[[Sketcher_Workbench|Sketcher]] |
|Workbenches=[[Sketcher_Workbench|Sketcher]] |
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|Version=0.19 |
|Version=0.19 |
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|SeeAlso= |
|SeeAlso=[[Sketcher_BSplineIncreaseDegree|Sketcher BSplineIncreaseDegree]] |
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}} |
}} |
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==Description== |
==Description== |
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The [[Image:Sketcher_BSplineDecreaseDegree.svg|24px]] [[Sketcher_BSplineDecreaseDegree|Sketcher BSplineDecreaseDegree]] tool decreases the degree (order) of [[B-Splines|B-splines]]. |
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Decreases the degree (order) of a B-spline (see [[B-Splines|this page]] for more info about B-splines). |
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B-splines are basically a combination of [https://en.wikipedia.org/wiki/Bezier_curve#Constructing_B%C3%A9zier_curves Bézier curves] (nicely explained in [https://www.youtube.com/watch?v=bE1MrrqBAl8 this] and [https://www.youtube.com/watch?v=xXJylM2S72s this] video). |
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# Select one or more B-splines. |
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In this cubic spline (degree 3) there are 3 segments, meaning 3 curves are connected at 2 knots<br>(the degree is indicated by the number, indication can be changed using the toolbar button {{Button|[[File:Sketcher_BSplineDegree.svg|24px]] [[Sketcher_BSplineDegree|Show/hide B-spline degree]]}}): |
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# There are several ways to invoke the tool: |
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#* Select the {{MenuCommand|Sketch → Sketcher B-spline tools → [[Image:Sketcher_BSplineDecreaseDegree.svg|16px]] Decrease B-spline degree}} option from the menu. |
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#* {{Version|1.0}}: Right-click in the [[3D_view|3D view]] and select the {{MenuCommand|[[Image:Sketcher_BSplineDecreaseDegree.svg|16px]] Decrease B-spline degree}} option from the context menu. |
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==Example== |
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[[File:Sketcher_BSplineDegree3.png|400px]] |
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{{Caption|B-spline with degree 3 and 2 knots that each have the multiplicity 1.}} |
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The outer segments have each 2 control points, the inner one none to fulfill the constraint that the knots have multiplicity 1. (see [[Sketcher_BSplineDecreaseKnotMultiplicity#Description|this page]] for an explanation of the multiplicity) |
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Decreasing the degree will not delete control points but try instead to conserve the shape of the spline. Therefore segments will be added. For our example you see a lot of new spline segments with each one control point and the shape of the spline has only slightly been changed: |
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[[File:Sketcher_BSplineDegree2.png|400px]] |
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{{Caption|Same B-spline where the degree was changed from 3 to 2. Note that also the knot multiplicity was increased to conserve the spline shape. In effect the knots have now ''C''<sup>0</sup> continuity so that the spline will get "edges" when you move a control point. (see [[Sketcher_BSplineDecreaseKnotMultiplicity#Description|this page]] to for an explanation of the continuity)}} |
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If you take this result and increase the degree, you cannot get the initial state of the spline because information was lost by the prior decrease of the degree. For our example increasing the degree again leads to this: |
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[[File:Sketcher_BSplineDegree3again.png|400px]] |
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{{Caption|Same B-spline where the degree was changed back from 2 to 3. Note that the knot multiplicity increased too because the information for a possible higher continuity was lost.}} |
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See [[Sketcher_BSplineIncreaseDegree#Example|Sketcher BSplineIncreaseDegree]]. |
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Latest revision as of 07:29, 22 April 2024
Sketcher BSplineDecreaseDegree |
Menu location |
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Sketch → Sketcher B-spline tools → Decrease B-spline degree |
Workbenches |
Sketcher |
Default shortcut |
None |
Introduced in version |
0.19 |
See also |
Sketcher BSplineIncreaseDegree |
Description
The Sketcher BSplineDecreaseDegree tool decreases the degree (order) of B-splines.
Usage
- Select one or more B-splines.
- There are several ways to invoke the tool:
- Press the Decrease B-spline degree button.
- Select the Sketch → Sketcher B-spline tools → Decrease B-spline degree option from the menu.
- introduced in version 1.0: Right-click in the 3D view and select the Decrease B-spline degree option from the context menu.
Example
See Sketcher BSplineIncreaseDegree.
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
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
- Workbenches: Std Base, Assembly, BIM, CAM, Draft, FEM, Inspection, Mesh, OpenSCAD, Part, PartDesign, Points, Reverse Engineering, Robot, Sketcher, Spreadsheet, Surface, TechDraw, Test Framework
- Hubs: User hub, Power users hub, Developer hub