| | BRepFeat is necessary for the
creation and manipulation of both form and mechanical features in a
Boundary Representation framework. Form features can be depressions or
protrusions and include the following types:
- Cylinder
- Draft Prism
- Prism
- Revolved feature
- Pipe
Depending on whether you wish to make a depression or a protrusion,
you can choose your operation type between the following:
- removing matter (a Boolean cut: Fuse setting 0)
- adding matter (Boolean fusion: Fuse setting 1)
The semantics of form feature creation is based on the
construction of shapes:
- for a certain length in a certain direction
- up to a limiting face
- from a limiting face at a height
- above and/or below a plane
The shape defining the construction of a feature can be either a
supporting edge or a concerned area of a face.
In case of supporting edge, this contour can be attached to a face
of the basis shape by binding. When the contour is bound to this face,
the information that the contour will slide on the face becomes
available to the relevant class methods. In case of the concerned
area of a face, you could, for example, cut it out and move it at
a different height, which will define the limiting face of a
protrusion or depression. Topological definition with local
operations of this sort makes calculations simpler and faster
than a global operation. The latter would entail a second phase of
removing unwanted matter to get the same result.
Mechanical features include ribs - protrusions - and grooves (or
slots) - depressions along planar (linear) surfaces or revolution surfaces.
The semantics of mechanical features is based on giving
thickness to a contour. This thickness can either be unilateral
- on one side of the contour - or bilateral - on both sides. As in
the semantics of form features, the thickness is defined by
construction of shapes in specific contexts.
However, in case of mechanical features, development contexts
differ. Here they include extrusion:
- to a limiting face of the basis shape
- to or from a limiting plane
- to a height.
More...
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1.6.3