Local Properties of Curves and Surfaces
The "Local Properties of Curves and Surfaces" component provides algorithms for computing various local properties on a curve (in 2D or 3D space) or on a surface.
Curves are either Geom_Curve curves (in 3D space) or Geom2d_Curve curves (in the plane). Surfaces are Geom_Surface surfaces. The point on which local properties are calculated is defined by its u parameter value on a curve, and its (u,v) parameter values on a surface.
The local properties which may be queried are:
- On a 2D curve:
- the points corresponding to a minimum or a maximum of curvature
- the inflection points
- The degree of continuity of a 3D curve built by concatenation of two other curves at their junction point
- On a point of parameter u on a 2D or 3D curve:
- the point
- the derivative vectors, up to the third degree
- the tangent vector
- the normal
- the curvature, and the center of curvature
- On a point of parameter (u,v) on a surface:
- the point
- the derivative vectors, up to the second degree
- the vectors tangent to the u and v isoparametric curves
- the normal vector
- the minimum or maximum curvature, and the corresponding directions of curvature.
The "Local Properties of Curves and Surfaces" component is composed of:
- The Geom2dLProp package, which provides local properties on 2D curves
- The GeomLProp package, which provides local properties on 3D curves and surfaces
- The LProp package, which provides an enumeration used to characterize a particular point on a 2D curve.
Note: The "Local Properties of Shapes" component (see the "Topology Reference Manual") also provides these computations, but directly on "BRep shapes".