A Part Feauture is the parent class of most 2D (Draft, Sketcher) and 3D (Part, PartDesign) objects, with the exception of meshes, which are normally based on Mesh Feature, or Fem FemMeshObject for FEM objects.
Simplified diagram of the relationships between the core objects in the program. The
Part::Feature class is the origin of most 2D (Draft, Sketcher) and 3D (Part, PartDesign) objects that have a Part TopoShape.
How to use
Part::Feature is defined in the Part Workbench but can be used as the base class for scripted objects in all workbenches that produce 2D and 3D geometrical shapes. Essentially all objects produced in the Part Workbench are instances of a
Part::Feature. Solid objects imported from STEP or BREP files will be imported using the Part Workbench, so they will also be imported as
Part::Feature elements albeit without parametric history.
Part::Feature has simple properties like a placement, and visual properties to define the appearance of its vertices, edges, and faces. Workbenches can add more properties to this basic element to produce an object with complex behavior.
In addition to the properties described in App GeoFeature, the Part Feature has the DataShape property, which stores the Part TopoShape of this object; this is the geometry that is shown in the 3D view.
Other properties that this object has are those related to the appearance of its TopoShape, including ViewAngular Deflection, ViewDeviation, ViewDraw Style, ViewLighting, ViewLine Color, ViewLine Width, ViewPoint Color, ViewPoint Size, and also the hidden properties ViewDiffuse Color, ViewLine Color Array, ViewLine Material, ViewPoint Color Array, and ViewPoint Material.
See Property for all property types that scripted objects can have.
- DataPlacement (
Placement): the position of the object in the 3D view. The placement is defined by a
Basepoint (vector), and a
Rotation(axis and angle). See Placement.
- DataAngle: the angle of rotation around the DataAxis. By default, it is
- DataAxis: the unit vector that defines the axis of rotation for the placement. Each component is a floating point value between
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).
- DataPosition: a vector with the 3D coordinates of the base point. By default, it is the origin
(0, 0, 0).
- DataAngle: the angle of rotation around the DataAxis. By default, it is
- DataLabel (
String): the user editable name of this object, it is an arbitrary UTF8 string.
Hidden properties Data
- Data (hidden)Expression Engine (
ExpressionEngine): a list of expressions. By default, it is empty
- Data (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
- Data (hidden)Proxy (
PythonObject): a custom class associated with this object. This only exists for the Python version. See Scripting.
- Data (hidden)Shape (
PartShape): a Part TopoShape class associated with this object.
- Data (hidden)Visibility (
Bool): whether to display the object or not.
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.
- ViewAngular Deflection (
Angle): it is a companion to ViewDeviation. 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.
- ViewBounding Box (
Bool): if it is , the object will show the bounding box in the 3D view.
- ViewDeviation (
FloatConstraint): it is a companion to ViewAngular 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
d are the bounding box dimensions.
- ViewDisplay Mode (
Flat Lines(regular visualization),
- ViewDraw Style (
Dashdot; defines the style of the edges in the 3D view.
- ViewLighting (
One side; the illumination comes from two sides or one side in the 3D view.
- ViewLine 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 .
- ViewLine Width (
FloatConstraint): a float that determines the width in pixels of the edges in the 3D view. It defaults to
- ViewOn Top When Selected (
- ViewPoint Color (
Color): similar to ViewLine Color, defines the color of the vertices.
- ViewPoint Size (
FloatConstraint): similar to ViewLine Width, defines the size of the vertices.
- ViewSelectable (
Bool): if it is , the object can be picked with the pointer in the 3D view. Otherwise, the object cannot be selected until this option is set to .
- ViewSelection Style (
BoundBox. If the option is
Shape, the entire shape (vertices, edges, and faces) will be highlighted in the 3D view; if it is
BoundBoxonly the bounding box will be highlighted.
- ViewShape Color (
Color): similar to ViewLine 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.
- ViewShow In Tree (
Bool): if it is , the object appears in the tree view. Otherwise, it is set as invisible.
- ViewTransparency (
Percent): an integer from
100(a percentage) that determines the level of transparency of the faces in the 3D view. A value of
100indicates completely invisible faces; the faces are invisible but they can still be picked as long as ViewSelectable is .
- ViewVisibility (
Bool): if it is , the object appears in the 3D view; otherwise it is invisible. By default this property can be toggled on and off by pressing the bar in the keyboard.
Hidden properties View
- View (hidden)Diffuse Color (
ColorList): it is a list of RGB tuples defining colors, similar to ViewShape Color. It defaults to a list of one
[(0.8, 0.8, 0.8)].
- View (hidden)Line Color Array (
ColorList): it is a list of RGB tuples defining colors, similar to ViewLine Color. It defaults to a list of one
[(0.09, 0.09, 0.09)].
- View (hidden)Line Material (
Material): an App Material associated with the edges in this object. By default it is empty.
- View (hidden)Point Color Array (
ColorList): it is a list of RGB tuples defining colors, similar to ViewPoint Color. It defaults to a list of one
[(0.09, 0.09, 0.09)].
- View (hidden)Point Material (
Material): an App Material associated with the vertices in this object. By default it is empty.
- View (hidden)Proxy (
PythonObject): a custom view provider class associated with this object. This only exists for the Python version. See Scripting.
- View (hidden)Shape Material (
Material): an App Material associated with this object. By default it is empty.
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"
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
import FreeCAD as App doc = App.newDocument() obj = App.ActiveDocument.addObject("Part::FeaturePython", "Name") obj.Label = "Custom label"
addObject function has two basic string arguments.
- The first argument indicates the type of object, in this case,
- The second argument is a string that defines the
Nameattribute. If it is not provided, it defaults to the same name as the class, that is,
Namecan 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
Namecannot start with a number; it must start with a letter or the underscore,
[_a-zA-Z]. For example,
"123ABC"is converted to
Nameis fixed at creation time; it cannot be modified afterwards.
Namemust 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
If desired, the
Label attribute can be changed to a more meaningful text.
- Upon creating the object, the
Labelis the same as the
- However, unlike the
Labelcan accept any UTF8 string, including accents and spaces. Since the tree view displays the
Label, it is a good practice to change the
Labelto a more descriptive string.
- By default the
Labelis 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
Labelmay be repeated in the same document; when testing for a specific element the user should rely on the
Namerather than on the