Std Part - Parte standard

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Std Part.svg Parte

Nome nel codice
Std Part
Posizione nel menu
Nessuno
Ambiente
Tutti
Avvio veloce
Nessuno
Introdotto nella versione
0.17
Vedere anche
Gruppo, Corpo


Descrizione

Std Part (internamente chiamato App Part) è un contenitore per scopi generali che contiene un gruppo di oggetti in modo che essi possano essere spostati in blocco come una singola unità nella vissta 3D.

L'elemento Parte Standard è stato sviluppato per essere l'elemento di base per creare assiemi meccanici. In particolare, ha lo scopo di disporre oggetti che hanno una forma topologica, come le primitive di Part, i corpi di PartDesign, e altre funzioni di Part. Std Part fornisce un oggetto Origine con assi X, Y e Z locali e piani standard; questa origine viene utilizzata come riferimento per posizionare e collegare quegli altri oggetti. Inoltre, le parti standard possono essere nidificate all'interno di altre parti standard per creare un assieme completo da sottoassiemi più piccoli.

Sebbene sia destinato principalmente a corpi solidi, Parte standard può essere utilizzato per gestire qualsiasi oggetto che abbia una proprietà Posizionamento, quindi può anche contenere funzioni Mesh, schizzi e altri oggetti derivati da App GeoFeature.

Lo strumento Std Part non è definito da un particolare ambiente di lavoro, ma dal sistema base; di conseguenza lo si trova nella barra degli strumenti struttura, che è disponibile in tutti gli ambienti di lavoro.

The Std Part.svg Std Part tool is not defined by a particular workbench, but by the base system, thus it is found in the structure toolbar that is available in all workbenches. To group objects arbitrarily without considering their position, use Std Group.svg Std Group; this object does not affect the placements of the elements that it contains, it is essentially just a folder that is used to keep the tree view organized.

Std Part-tree.pngStd Part example.png

A sinistra: elementi all'interno di una Parte Std nella vista ad albero. A destra: oggetti posizionati nello spazio, riferiti all'Origine della Parte Std.


Utilizzo

  • Premere il pulsante Std Part.png Crea parte nella barra degli strumenti. La parte diventa automaticamente attiva.
  • Fare doppio clic sulla parte nell'albero del modello per attivarla o disattivarla.
  • Per aggiungere oggetti a una parte, trascinali e rilasciali sulla parte nell'albero del modello.
  • Per rimuovere oggetti da una parte, trascinali e rilasciali fuori dalla parte e sull'etichetta del documento nella parte superiore dell'albero del modello.

Note

  • As of v0.19, a given object can only belong to a single Part.
  • Double-click the Part in the tree view or open the context menu (right-click) and select Toggle active part to activate or deactivate the Part. If another Part is active, it will be deactivated. See active status for more information.

Limitazioni

  • Anche quando una parte è attiva, gli oggetti appena creati non sono collocati all'interno della parte, ma al fondo dell'albero. Basta trascinarli sulla parte.
  • Una parte non ha forma. Pertanto, non è possibile applicare la maggior parte delle operazioni 3D su una parte, ad esempio lo operazioni booleane di Part.
  • Nota del redattore: al momento non è chiaro se lo stato attivo della Parte abbia uno scopo.

Proprietà

A Std Part is internally called App Part (App::Part class), and is derived from an App GeoFeature (App::GeoFeature class), therefore it shares most of the latter's properties.

In addition to the properties described in App GeoFeature, the App Part class has some properties that help it manage information in the context of an assembly, for example, DataType, DataId, DataLicense, DataLicenseURL, DataColor, and DataGroup.

These are the properties available in the property editor. Hidden properties can be shown by using the Show all command in the context menu of the property editor.

Data

Base

  • DatiId: ID (Numero di parte) dell'elemento. Questo campo è facoltativo.
  • DatiLicense: la licenza con cui viene rilasciata la parte.
  • DatiLicense URL: l'indirizzo Web in cui è possibile trovare i termini della licenza.
  • DatiPlacement: specifica l'orientamento e la posizione della parte nello spazio 3D. Vedere Posizionamento.
  • DatiLabel: l'etichetta è il nome dato all'operazione. Questo nome può essere cambiato a piacimento.
  • DatiGroup: elenca gli oggetti riferiti.

Hidden properties Data

  • DataMaterial (Map): map with material properties. By default, it is empty {}.
  • DataMeta (Map): map with additional meta information. By default, it is empty {}.
  • DataUid (UUID): the universally unique identifier (UUID) (128-bit number) of the object. This is assigned at creation time.
  • DataLabel2 (String): a longer, user editable description of this object, it is an arbitrary UTF8 string that may include newlines. By default, it is an empty string "".
  • DataExpression Engine (ExpressionEngine): a list of expressions. By default, it is empty [].
  • DataVisibility (Bool): whether to display the object or not.
  • DataOrigin (Link): the App Origin object that is the positional reference for all elements listed in DataGroup.
  • Data_ Group Touched (Bool): whether the group is touched or not.

View

The App Part only has the five properties of the basic App FeaturePython, and it does not have hidden properties.

Base

  • ViewDisplay Mode (Enumeration): Group.
  • ViewOn Top When Selected (Enumeration): Disabled (default), Enabled, Object, Element.
  • ViewSelection Style (Enumeration): Shape (default), BoundBox. If the option is Shape, the entire shape (vertices, edges, and faces) will be highlighted in the 3D view; if it is BoundBox only the bounding box will be highlighted.
  • ViewShow In Tree (Bool): if it is True, the object appears in the tree view. Otherwise, it is set as invisible.
  • ViewVisibility (Bool): if it is True, the object appears in the 3D view; otherwise it is invisible. By default this property can be toggled on and off by pressing the Space bar in the keyboard.

Concetto di assemblaggio

The Std Part is intended to be the basic building block to create assemblies. Unlike a PartDesign Body, an assembly is meant to be a collection of separate, distinguishable elements which are connected in some way in the physical world, for example, through pressure, screws, or glue.

Examples that could be Parts:

  • A wooden table that consists of individual wooden pieces (legs, top), which are put together by glue or metal screws.
  • A ball bearing that is composed of multiple steel balls, an inner ring, a retainer, a seal, and an outer ring.
  • An assembly of a screw with a washer, and a matching nut.

PartDesign Body contiguous separate.png PartDesign Body contiguous assembly.png

Left: three individual contiguous solids, each of them modelled by a PartDesign Body. Right: the individual Bodies put together inside a Std Part to create an assembly.


In general terms, when importing a STEP file into the program, the main assembly and its sub-assemblies will be imported as Part containers, each of them containing a simple Part Feature.

Detailed explanation

Stato attivo

An open document can contain multiple Parts. An active Part will be displayed in the tree view with the background color specified by the Active container value in the preferences editor (by default, light blue). An active part will also be shown in bold text.

To activate or de-activate a Part:

  • Double click on it on the tree view, or
  • Open the context menu (right click) and select Toggle active part.

Notes:

  • The active status of Parts was developed in v0.17 in parallel with the active status of PartDesign Bodies; however, as of v0.19 this status does not serve a real purpose for Parts.
  • Even when a Part is active, newly created objects are not placed inside of it automatically. In this case, simply drag these new objects, and drop them onto the desired Part.
  • Only a single Part can be active at a time.

Std Part active.png

Document with two Std Parts, of which the second one is active.


Origine

The Origin consists of the three standard axes (X, Y, Z) and three standard planes (XY, XZ and YZ). Sketches and other objects can be attached to these elements when creating them.

Part Origin tree.png Part Origin view.png

Left: Part Origin in the tree view. Right: representation of the Origin elements in the 3D view.


Note: the Origin is an App Origin object (App::Origin class), while the axes and planes are objects of type App::Line and App::Plane respectively. Each of these elements can be hidden and unhidden individually with the Space bar; this is useful to choose the correct reference when creating other objects.

Note 2: all elements inside the Part are referenced to the Part's Origin which means that the Part can be moved and rotated in reference to the global coordinate system without affecting the placement of the elements inside.

Gestione della visibilità

The Part's visibility supersedes the visibility of any object it contains. If the Part is hidden, the objects it contains will be hidden as well, even if their individual ViewVisibility property is set to True. If the Part is visible, then each object's ViewVisibility determines whether the object is shown or not.

Part Visibility off.png Part Visibility on.png

The visibility of the Std Part determines whether the objects grouped under it are shown in the 3D view or not. Left: the Part is hidden, so none of the objects will be shown in the 3D view. Right: the Part is visible, so each object controls its own visibility.


Inheritance

A Std Part is formally an instance of the class App::Part, whose parent is the basic App GeoFeature (App::GeoFeature class), and is augmented with an Origin extension.

FreeCAD core objects.svg

Simplified diagram of the relationships between the core objects in the program. The App::Part class is a simple container that has a position in 3D space, and has an Origin to control the placement of the objects grouped under it.


Scripting

See also: FreeCAD Scripting Basics, and scripted objects.

See Part Feature for the general information on adding objects to the document.

A Std Part (App Part) is created with the addObject() method of the document. Once a Part exists, other objects can be added to it with the addObject() or addObjects() methods of this Part.

import FreeCAD as App

doc = App.newDocument()
obj = App.ActiveDocument.addObject("App::Part", "Part")

bod1 = App.ActiveDocument.addObject("PartDesign::Body", "Body")
bod2 = App.ActiveDocument.addObject("Part::Box", "Box")

obj.addObjects([bod1, bod2])
App.ActiveDocument.recompute()

A Part is a container for other objects, so it doesn't have its own Shape (Part TopoShape). However, in expressions or in the Spreadsheet Workbench, it is useful to get the compound shape of all objects contained inside the Part. This can be accomplished by using the _shape pseudo-property, which can then be used to extract other attributes.

=Part._shape.Edges[0].Length
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