Sketcher BSplineDecreaseDegree/ru: Difference between revisions

From FreeCAD Documentation
(Created page with "Уменьшает степень (порядок) B-сплайна (дополнительную информацию о B-сплайнах см. B-Splines/ru|на этой...")
(Updating to match new version of source page)
 
(4 intermediate revisions by one other user not shown)
Line 10: Line 10:
}}
}}


<div class="mw-translate-fuzzy">
{{GuiCommand/ru
{{GuiCommand/ru
|Name/ru=Уменьшить степень B-сплайна
|Name/ru=Уменьшить степень B-сплайна
Line 18: Line 19:
|SeeAlso=[[Sketcher_BSplineDegree/ru|Показать/скрыть степень B-сплайна]], [[Sketcher_BSplineIncreaseDegree/ru|Увеличить степень B-сплайна]]
|SeeAlso=[[Sketcher_BSplineDegree/ru|Показать/скрыть степень B-сплайна]], [[Sketcher_BSplineIncreaseDegree/ru|Увеличить степень B-сплайна]]
}}
}}
</div>


<span id="Description"></span>
==Описание==
==Описание==


<div class="mw-translate-fuzzy">
Уменьшает степень (порядок) B-сплайна (дополнительную информацию о B-сплайнах см. [[B-Splines/ru|на этой странице]]).
Уменьшает степень (порядок) B-сплайна (дополнительную информацию о B-сплайнах см. [[B-Splines/ru|на этой странице]]).
</div>


<span id="Usage"></span>
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).
==Применение==


<div class="mw-translate-fuzzy">
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]]}}):
# Выберите ребро существующего B-сплайна и нажмите {{Button|[[File:Sketcher_BSplineDecreaseDegree.svg|24px]] '''Decrease B-spline degree'''}}
</div>


==Example==
[[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)}}

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:

[[File:Sketcher_BSplineDegree3again.png|400px]]
{{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.}}

==Применение==


See [[Sketcher_BSplineIncreaseDegree#Example|Sketcher BSplineIncreaseDegree]].
# Select an edge from an existing B-spline, and press {{Button|[[File:Sketcher_BSplineDecreaseDegree.svg|24px]] '''Decrease B-spline degree'''}}.





Latest revision as of 07:29, 22 April 2024

Other languages:

Уменьшить степень B-сплайна

Системное название
Sketcher_BSplineDecreaseDegree
Расположение в меню
Sketch → B-сплйан инструменты эскиза → Уменьшить степень B-сплайна
Верстаки
Sketcher
Быстрые клавиши
Нет
Представлено в версии
0.19
См. также
Показать/скрыть степень B-сплайна, Увеличить степень B-сплайна

Описание

Уменьшает степень (порядок) B-сплайна (дополнительную информацию о B-сплайнах см. на этой странице).

Применение

  1. Выберите ребро существующего B-сплайна и нажмите Decrease B-spline degree

Example

See Sketcher BSplineIncreaseDegree.