Part Formelement

From FreeCAD Documentation
Revision as of 09:16, 5 May 2020 by Maker (talk | contribs) (Created page with "Siehe Eigenschaft für alle Eigenschaftstypen, die geskriptete Objekte haben können.")

Einleitung

Ein Part Formelement, oder formal ein Part::Feature, ist ein einfaches Element mit einer topologische Form, das in der 3D Ansicht angezeigt werden kann.

Ein Part Formelement ist die Vorgängerklasse der meisten 2D (Entwurf, Skizzierer) und 3D im (Part, Part Design) Objekte, mit Ausnahme von Polygonnetzen, die normalerweise auf Polygonnetz Formelemente, oder Fem FemPolygonnetzObjekt für FEM Objekte basieren.

Jedes mit der Part Arbeitsbereich erstellte Objekt ist im Wesentlichen ein Part Formelement.

Vereinfachtes Diagramm der Beziehungen zwischen den Kernobjekten im Programm. Die Part::Feature Klasse ist der Ursprung der meisten 2D (Entwurf, Skizzierer) und 3D (Part, PartDesign) Objekte, die eine Part TopoForm haben.

Verwendung

Das Part Formelement ist ein internes Objekt, daher kann es nicht von der grafischen Oberfläche aus erstellt werden, sondern nur von der Python Konsole aus, wie im Abschnitt Skripten beschrieben.

Der Teil::Feature wird in der Part Arbeitsbereich definiert, kann aber als Basisklasse für skriptierte Objekte in allen Arbeitsbereichen verwendet werden, die 2D und 3D Geometrieformen erzeugen. Im Wesentlichen sind alle im Part Arbeitsbereich erzeugten Objekte Instanzen eines Part::Feature. Festkörperobjekte, die aus STEP oder BREP Dateien importiert werden, werden mit dem Part Arbeitsbereich importiert, so dass sie auch als Part::Feature Elemente importiert werden, wenn auch ohne parametrische Historie.

Part::Feature ist auch die Vorgängerklasse des PartDesign Körper, der PartDesign Formelemente und der Part Part2DObjekt, die auf 2D (planare) Formen zugeschnitten ist.

Ein Part::Feature hat einfache Eigenschaften wie eine Platzierung und visuelle Eigenschaften, um das Aussehen seiner Knoten, Kanten und Flächen zu definieren. Arbeitsbereiche können diesem Grundelement weitere Eigenschaften hinzufügen, um ein Objekt mit komplexem Verhalten zu erzeugen.

Eigenschaften

Eine Part Formelement (Part::Feature Klasse) wird von der Basisklasse App GeoFormelement (App::GeoFeature Klasse) abgeleitet, daher teilt sie alle Eigenschaften der letzteren.

Zusätzlich zu den in App GeoFormelement beschriebenen Eigenschaften verfügt das Part Feature über die Daten-EigenschaftFormEigenschaft, die die Part TopoForm dieses Objekts speichert; dies ist die Geometrie, die in der 3D Ansicht angezeigt wird.

Weitere Eigenschaften die dieses Objekt hat beziehen sich auf das Aussehen seines TopoForm, einschließlich Ansicht-EigenschaftWinkelablenkung, Ansicht-EigenschaftAbweichung, Ansicht-EigenschaftZeichenstil, Ansicht-EigenschaftBeleuchtung, Ansicht-EigenschaftLinienfarbe, Ansicht-EigenschaftLinienbreite, Ansicht-EigenschaftPunktfarbe, Ansicht-EigenschaftPunktgröße, und eben die versteckten Eigenschaften Ansicht-EigenschaftDiffuse Farbgebung, Ansicht-EigenschaftLinienfarben Anordnung, Ansicht-EigenschaftLinienmaterial, Ansicht-EigenschaftPunkt Farbanordnung, und Ansicht-EigenschaftPunktmaterial.

Siehe Eigenschaft für alle Eigenschaftstypen, die geskriptete Objekte haben können.

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

  • DatenPlacement (Placement): the position of the object in the 3D view. The placement is defined by a Base point (vector), and a Rotation (axis and angle). See Placement.
    • DatenAngle: the angle of rotation around the DatenAxis. By default, it is (zero degrees).
    • DatenAxis: the unit vector that defines the axis of rotation for the placement. Each component is a floating point value between 0 and 1. If any value is above 1, the vector is normalized so that the magnitude of the vector is 1. By default, it is the positive Z axis, (0, 0, 1).
    • DatenPosition: a vector with the 3D coordinates of the base point. By default, it is the origin (0, 0, 0).
  • DatenLabel (String): the user editable name of this object, it is an arbitrary UTF8 string.

Hidden properties Data

  • Daten (hidden)Expression Engine (ExpressionEngine): a list of expressions. By default, it is empty [].
  • Daten (hidden)Label2 (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 "".
  • Daten (hidden)Proxy (PythonObject): a custom class associated with this object. This only exists for the Python version. See Scripting.
  • Daten (hidden)Shape (PartShape): a Part TopoShape class associated with this object.
  • Daten (hidden)Visibility (Bool): whether to display the object or not.

View

Most objects in FreeCAD have what is called a "view provider", which is a class that defines the visual appearance of the object in the 3D view, and in the tree view. The default view provider of Part Feature objects defines the following properties. Scripted objects that are derived from Part Feature will have access to these properties as well.

Base

  • AnsichtAngular Deflection (Angle): it is a companion to AnsichtDeviation. It is another way to specify how finely to generate the mesh for rendering on screen or when exporting. The default value is 28.5 degrees, or 0.5 radians. This is the maximum value, the smaller the value the smoother the appearance will be in the 3D view, and the finer the mesh that will be exported.
  • AnsichtBounding Box (Bool): if it is true, the object will show the bounding box in the 3D view.
  • AnsichtDeviation (FloatConstraint): it is a companion to AnsichtAngular Deflection. It is another way to specify how finely to generate the mesh for rendering on screen or when exporting. The default value is 0.5%. This is the maximum value, the smaller the value the smoother the appearance will be in the 3D view, and the finer the mesh that will be exported.

The deviation is a value in percentage that is related to the dimensions in millimeters of the bounding box of the object. The deviation in millimeters can be calculated as follows:

deviation_in_mm = (w + h + d)/3 * deviation/100

where w, h, d are the bounding box dimensions.

  • AnsichtDisplay Mode (Enumeration): Flat Lines (regular visualization), Shaded (no edges), Wireframe (no faces), Points (only vertices).
  • AnsichtDraw Style (Enumeration): Solid (default), Dashed, Dotted, Dashdot; defines the style of the edges in the 3D view.
  • AnsichtLighting (Enumeration): Two side (default), One side; the illumination comes from two sides or one side in the 3D view.
  • AnsichtLine Color (Color): a tuple of three floating point RGB values (r,g,b) to define the color of the edges in the 3D view; by default it is (0.09, 0.09, 0.09), which is displayed as [25,25,25] on base 255, almost black .
  • AnsichtLine Width (FloatConstraint): a float that determines the width in pixels of the edges in the 3D view. It defaults to 2.0.
  • AnsichtOn Top When Selected (Enumeration): Disabled (default), Enabled, Object, Element.
  • AnsichtPoint Color (Color): similar to AnsichtLine Color, defines the color of the vertices.
  • AnsichtPoint Size (FloatConstraint): similar to AnsichtLine Width, defines the size of the vertices.
  • AnsichtSelectable (Bool): if it is true, the object can be picked with the pointer in the 3D view. Otherwise, the object cannot be selected until this option is set to true.
  • AnsichtSelection 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.
  • AnsichtShape Color (Color): similar to AnsichtLine Color, defines the color of the faces. It defaults to (0.8, 0.8, 0.8), which is displayed as [204,204,204] on base 255, a light gray.
  • AnsichtShow In Tree (Bool): if it is true, the object appears in the tree view. Otherwise, it is set as invisible.
  • AnsichtTransparency (Percent): an integer from 0 to 100 (a percentage) that determines the level of transparency of the faces in the 3D view. A value of 100 indicates completely invisible faces; the faces are invisible but they can still be picked as long as AnsichtSelectable is true.
  • AnsichtVisibility (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.

Hidden properties View

  • Ansicht (hidden)Diffuse Color (ColorList): it is a list of RGB tuples defining colors, similar to AnsichtShape Color. It defaults to a list of one [(0.8, 0.8, 0.8)].
  • Ansicht (hidden)Line Color Array (ColorList): it is a list of RGB tuples defining colors, similar to AnsichtLine Color. It defaults to a list of one [(0.09, 0.09, 0.09)].
  • Ansicht (hidden)Line Material (Material): an App Material associated with the edges in this object. By default it is empty.
  • Ansicht (hidden)Point Color Array (ColorList): it is a list of RGB tuples defining colors, similar to AnsichtPoint Color. It defaults to a list of one [(0.09, 0.09, 0.09)].
  • Ansicht (hidden)Point Material (Material): an App Material associated with the vertices in this object. By default it is empty.
  • Ansicht (hidden)Proxy (PythonObject): a custom view provider class associated with this object. This only exists for the Python version. See Scripting.
  • Ansicht (hidden)Shape Material (Material): an App Material associated with this object. By default it is empty.

Scripting

See also: FreeCAD Scripting Basics, and scripted objects.

A Part Feature is created with the addObject() method of the document.

import FreeCAD as App

doc = App.newDocument()
obj = App.ActiveDocument.addObject("Part::Feature", "Name")
obj.Label = "Custom label"

This basic Part::Feature doesn't have a Proxy object so it can't be fully used for sub-classing.

Therefore, for Python subclassing, you should create the Part::FeaturePython object.

import FreeCAD as App

doc = App.newDocument()
obj = App.ActiveDocument.addObject("Part::FeaturePython", "Name")
obj.Label = "Custom label"

Name

The addObject function has two basic string arguments.

  • The first argument indicates the type of object, in this case, "Part::FeaturePython".
  • The second argument is a string that defines the Name attribute. If it is not provided, it defaults to the same name as the class, that is, "Part__FeaturePython".
    • The Name can only include simple alphanumeric characters, and the underscore, [_0-9a-zA-Z]. If other symbols are given, these will be converted to underscores; for example, "A+B:C*" is converted to "A_B_C_".
    • The Name cannot start with a number; it must start with a letter or the underscore, [_a-zA-Z]. For example, "123ABC" is converted to "_23ABC".
    • The Name is fixed at creation time; it cannot be modified afterwards.
    • The Name must be unique in the entire document. If the same "Name" is used at creation time with many objects, a sequential number will be appended automatically so that the resulting names are unique; for example, if "Name" already exists, then new objects will be called "Name001", "Name002", "Name003", etc.

Label

If desired, the Label attribute can be changed to a more meaningful text.

  • Upon creating the object, the Label is the same as the Name.
  • However, unlike the Name, the Label can accept any UTF8 string, including accents and spaces. Since the tree view displays the Label, it is a good practice to change the Label to a more descriptive string.
  • By default the Label is unique, just like the Name. However, this behavior can be changed in the preferences editor, Edit → Preferences → General → Document → Allow duplicate object labels in one document. This means that in general the Label may be repeated in the same document; when testing for a specific element the user should rely on the Name rather than on the Label.