Mesh Feature

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Introduction

A Tree Mesh.svg Mesh Feature object, or formally a Mesh::Feature, is a simple element with a mesh object associated to it that can be displayed in the 3D view.

A Mesh Feature is similar conceptually to a Part Feature; the former is the base object for elements with "mesh" information, while the latter is the base object for elements with "geometrical shape" information.

Please note that the Workbench FEM.svg FEM Workbench also uses meshes, but in this case it uses a different object, called Fem FemMeshObject (Fem::FemMeshObject class). This object is not derived from Mesh Feature so it has different properties.

FreeCAD core objects.svg

Simplified diagram of the relationships between the core objects in the program. The Mesh::Feature class is the origin of most objects that posses a triangular mesh. These objects are created from the Mesh Workbench or by importing STL, OBJ, and similar mesh format files.


Usage

The Mesh Feature is an internal object, so it cannot be created from the graphical interface, only from the Python console as described in the Scripting section.

The Mesh::Feature is defined in the Mesh Workbench but can be used as the base class for scripted objects in all workbenches that produce 2D and 3D meshes.

A Mesh::Feature has simple properties like a placement, and visual properties to define the appearance of its edges and faces. Workbenches can add more properties to this basic element to produce an object with complex behavior.

Properties

A Mesh Feature (Mesh::Feature class) is derived from the basic App GeoFeature (App::GeoFeature class), therefore it shares all the latter's properties.

In addition to the properties described in App GeoFeature, the Mesh Feature has the DataMesh property, which stores the Mesh MeshObject of this element; 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 Mesh MeshObject, including ViewCrease Angle, ViewLighting, ViewLine Color, ViewLine Transparency, ViewLine Width, ViewOpen Edges, ViewPoint Size, and also the hidden property ViewColoring.

See Property for all property types that scripted objects can have.

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

  • DataMesh (MeshKernel): a Mesh MeshObject class associated with this object. It lists the number of Points, Edges, and Faces of the mesh.
  • DataPlacement (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.
    • DataAngle: the angle of rotation around the DataAxis. By default, it is (zero degrees).
    • DataAxis: 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).
    • DataPosition: a vector with the 3D coordinates of the base point. By default, it is the origin (0, 0, 0).
  • DataLabel (String): the user editable name of this object, it is an arbitrary UTF8 string.

Hidden properties Data

  • DataExpression Engine (ExpressionEngine): a list of expressions. By default, it is empty [].
  • 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 "".
  • DataProxy (PythonObject): a custom class associated with this object. This only exists for the Python version. See Scripting.
  • DataVisibility (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 Mesh Feature objects defines the following properties. Scripted objects that are derived from Mesh Feature will have access to these properties as well.

Base

  • ViewBounding Box (Bool): if it is True, the object will show the bounding box in the 3D view.
  • ViewCrease Angle (FloatConstraint):
  • ViewDisplay Mode (Enumeration): Shaded (no edges), Wireframe (no faces), Flat Lines (regular visualization), Points (only vertices).
  • ViewLighting (Enumeration): One side (default), Two 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 (0.0, 0.0, 0.0), which is displayed as [0,0,0] on base 255, completely black .
  • ViewLine Transparency (Percent): an integer from 0 to 100 (a percentage) that determines the level of transparency of the edges in the 3D view. A value of 100 indicates completely invisible edges; the edges are invisible but they can still be picked as long as ViewSelectable is True.
  • ViewLine Width (FloatConstraint): a float that determines the width in pixels of the edges in the 3D view. It defaults to 1.0.
  • ViewOn Top When Selected (Enumeration): Disabled (default), Enabled, Object, Element.
  • ViewOpen Edges (Bool): it defaults to False.
  • ViewPoint Size (FloatConstraint): similar to ViewLine Width, defines the size of the vertices.
  • ViewSelectable (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.
  • 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.
  • 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 True, the object appears in the tree view. Otherwise, it is set as invisible.
  • ViewTransparency (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 ViewSelectable is True.
  • 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.

Hidden properties View

  • ViewColoring (Bool): it defaults to False.
  • ViewProxy (PythonObject): a custom view provider class associated with this object. This only exists for the Python version. See Scripting.
  • ViewShape Material (Material): an App Material associated with this object. By default it is empty.

Scripting

See also: FreeCAD Scripting Basics, and scripted objects.

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

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

import FreeCAD as App

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

This basic Mesh::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 Mesh::FeaturePython object.

import FreeCAD as App

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