IDiffSurface_KC Interface
 GetNormalAt
 GetProximity
 GetLocalParametrization
IDiffSurface_KC interface returns normal vector to surface of the object the
interface was queried from. The interface can be queried from
ISection. Not all types of entities implement
this interface. Mesh entities do implement
it.
See also: Interface List
HRESULT GetNormalAt(DIPoint* pointAt, DIPoint* normal, int *count)
Parameters
pointAt  [in] Point where the normal to be calculated
normal  [out] Calculated normal to the surface at
point pointAt
count  [out, retval] Count of
normals at the point. Value of 0 means an error.
 Remarks:
The method calculates normal at point on surface of the object this interface
was queried from. When pointAt is not located exactly on the
surface a nearest point is calculated and normal at the point is returned. See
also comments for the next method.
The method is a simplified version of the GetProximity method below for
a case when it is known that the surface is smooth at the point and has a single
normal. It is recommended to verify this assumption by checking the returned
count value.
The returned count number indicates how many normals the
surface has at the point. When point belong to a smooth surface patch the
count is 1. When the point is located on a smooth edge the count
is 2. When the point is located at a corner count will be equal to
number of smooth patches joined at the corner. Value of 0 means an error.
The normal contains only the first normal.at the
point.
HRESULT GetProximity(DIPoint* pointAt,
IVertex** vertex)
Parameters
pointAt  [in] Point where the normal to be calculated
vertex  [out, retval] The returned
vertex, which contains array of all normals at the point
 Remarks:
See also remark for the previous method. This method contains full
information about normals at the point. Use methods of
IVertex
to access array of normals.
In case when pointAt is not located exactly on the surface
coordinates returned by
IVertex.GetVertexCoord are coordinates of the nearest point on the surface.
This can be used to verify that pointAt is close to the surface.
HRESULT GetLocalParametrization(DIPoint* pointAt,
IKO_Geom_BSplineSurface** patch)
Parameters
pointAt  [in] Center of approximation
patch  [out, retval] The returned
BSpline patch which approximates the surface
 Remarks:

Returns a BSpline patch which approximates the surface around pointAt.
If this interface was queried from a entity, which is part of a model, a new
entity geometry of which is the returned patch will be added to the model as
the last toplevel object. This object can be deleted if no representation in
the scene is required. The patch in this case is still a valid usable object.
