Sketcher BSplineDecreaseDegree/fr: Difference between revisions

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{{Docnav/fr
{{Docnav/fr
|[[Sketcher_BSplineIncreaseDegree/fr|Augmenter degré de B-spline]]
|[[Sketcher_BSplineIncreaseDegree/fr|Augmenter degré de B-spline]]
|[[Sketcher_BSplineIncreaseKnotMultiplicity/fr|Plus de nœuds d'une B-spline]]
|[[Sketcher_BSplineIncreaseKnotMultiplicity/fr|Augmenter la multiplicité d'un nœud]]
|[[Sketcher_Workbench/fr|Atelier Sketcher]]
|[[Sketcher_Workbench/fr|Atelier Sketcher]]
|IconL=Sketcher_BSplineIncreaseDegree.svg
|IconL=Sketcher_BSplineIncreaseDegree.svg
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}}
}}


{{GuiCommand
{{GuiCommand/fr
|Name=Sketcher BSplineDecreaseDegree
|Name=Sketcher BSplineDecreaseDegree
|MenuLocation=Sketch → Sketcher B-spline tools → Decrease Degree of B-spline
|Name/fr=Sketcher Diminuer le degré d'une B-spline
|MenuLocation=Esquisse → Outils d'esquisse des B-splines → Diminuer le degré de la B-spline
|Workbenches=[[Sketcher_Workbench|Sketcher]]
|Workbenches=[[Sketcher_Workbench/fr|Sketcher]]
|Version=0.19
|Version=0.19
|SeeAlso=[[Sketcher_BSplineDegree|Sketcher Show/hide B-spline degree]], [[Sketcher_BSplineIncreaseDegree|Sketcher Increase B-spline degree]]
|SeeAlso=[[Sketcher_BSplineIncreaseDegree/fr|Sketcher Augmenter le degré d'une B-spline]]
}}
}}


==Description==
==Description==


L'outil [[Image:Sketcher_BSplineDecreaseDegree.svg|24px]] [[Sketcher_BSplineDecreaseDegree/fr|Sketcher Diminuer le degré d'une B-spline]] diminue le degré (l'ordre) des [[B-Splines/fr|B-splines]].
Decreases the degree (order) of the B-spline.

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).

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]]}}):

[[File:Sketcher_BSplineDegree3.png|400px]]
{{Caption|B-spline with degree 3 and 2 knots that each have the multiplicity 1.}}

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)

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:

[[File:Sketcher_BSplineDegree2.png|400px]]
{{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)}}


<span id="Usage"></span>
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:
==Utilisation==


# Sélectionnez une ou plusieurs B-splines.
[[File:Sketcher_BSplineDegree3again.png|400px]]
# Il y a plusieurs façons de lancer l'outil :
{{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.}}
#* Appuyez sur le bouton {{Button|[[Image:Sketcher_BSplineDecreaseDegree.svg|16px]] [[Sketcher_BSplineDecreaseDegree/fr|Diminuer le degré de la B-spline]]}}.
#* Sélectionnez l'option {{MenuCommand|Esquisse → Outils d'esquisse des B-splines → [[Image:Sketcher_BSplineDecreaseDegree.svg|16px]] Diminuer le degré de la B-spline}} du menu.
#* {{Version/fr|1.0}} : cliquez avec le bouton droit de la souris dans la [[3D_view/fr|vue 3D]] et sélectionnez l'option {{MenuCommand|[[Image:Sketcher_BSplineDecreaseDegree.svg|16px]] Diminuer le degré de la B-spline}} du menu contextuel.


<span id="Example"></span>
==Usage==
==Exemple==


Voir [[Sketcher_BSplineIncreaseDegree/fr#Exemple|Sketcher Augmenter le degré d'une B-spline]].
# Select an edge from an existing B-spline, and press {{Button|[[File:Sketcher_BSplineDecreaseDegree.svg|24px]] '''Decrease B-spline degree'''}}.




{{Docnav/fr
{{Docnav/fr
|[[Sketcher_BSplineIncreaseDegree/fr|Augmenter degré de B-spline]]
|[[Sketcher_BSplineIncreaseDegree/fr|Augmenter degré de B-spline]]
|[[Sketcher_BSplineIncreaseKnotMultiplicity/fr|Plus de nœuds d'une B-spline]]
|[[Sketcher_BSplineIncreaseKnotMultiplicity/fr|Augmenter la multiplicité d'un nœud]]
|[[Sketcher_Workbench/fr|Atelier Sketcher]]
|[[Sketcher_Workbench/fr|Atelier Sketcher]]
|IconL=Sketcher_BSplineIncreaseDegree.svg
|IconL=Sketcher_BSplineIncreaseDegree.svg
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{{Sketcher Tools navi{{#translation:}}}}
{{Sketcher Tools navi{{#translation:}}}}
{{Userdocnavi{{#translation:}}}}
{{Userdocnavi{{#translation:}}}}
{{clear}}

Latest revision as of 08:37, 28 April 2024

Sketcher Diminuer le degré d'une B-spline

Emplacement du menu
Esquisse → Outils d'esquisse des B-splines → Diminuer le degré de la B-spline
Ateliers
Sketcher
Raccourci par défaut
Aucun
Introduit dans la version
0.19
Voir aussi
Sketcher Augmenter le degré d'une B-spline

Description

L'outil Sketcher Diminuer le degré d'une B-spline diminue le degré (l'ordre) des B-splines.

Utilisation

  1. Sélectionnez une ou plusieurs B-splines.
  2. Il y a plusieurs façons de lancer l'outil :
    • Appuyez sur le bouton Diminuer le degré de la B-spline.
    • Sélectionnez l'option Esquisse → Outils d'esquisse des B-splines → Diminuer le degré de la B-spline du menu.
    • introduit dans la version 1.0 : cliquez avec le bouton droit de la souris dans la vue 3D et sélectionnez l'option Diminuer le degré de la B-spline du menu contextuel.

Exemple

Voir Sketcher Augmenter le degré d'une B-spline.