IArcEx Interface
- GetPoint
- GetRadius
- SetRadius
- IsValid
- GetCenter
- GetAngleRange
- PassThroughPoint
The interface is implemented by Arcs. It
allows calculation of additional properties associated with an arc. Basic
properties of an arc can be accessed via IArc and
ILine2D.
Before calling GetPoint, GetCenter
or GetAngleRange methods of this interface the arc must
be initialized.
See also Patchwork sample,
Interface List
HRESULT GetPoint(double t, double* x, double* y)
Parameters
t - [in]
Normalized Natural
Parameter along the arc. t must be in range [0, 1]
x, y - [out] returned coordinates of the point
-
- Remarks:
The method returns point at position t on the arc.
HRESULT GetRadius(double* r)
Parameters
r - [out, retval] Returned radius
-
- Remarks:
The method is provided for convenience. It returns 1.0 /
Curvature. When curvature is zero a
large positive number ( 1.7E+308 ) is returned.
HRESULT SetRadius(double r)
Parameters
r - [in] New radius for the arc. See remarks below
Return Values
- S_OK in case of
success.
DISP_E_PARAMNOTOPTIONAL if r is 0
-
- Remarks:
The method changes curvature Curvature
to 1 / r. r must not be 0. The method does no check validity of
the resulting arc, assuming that further modifications may follow before usage
of the arc object. If arc has been modified with this method the Init method
below must be called prior calling any other methods of IArcEx.
HRESULT IsValid(VARIANT_BOOL *valid)
Parameters
valid - [out, retval] returned validity of the arc
-
- Remarks:
The method returns true if the arc is
valid.
HRESULT GetCenter(double* x, double* y)
Parameters
x, y - [out] The returned center of the arc
-
- Remarks:
Calculates center of the arc. The arc must be
valid and
initialized
HRESULT GetAngleRange(double* a, double* b)
Parameters
a - [out] Polar angle of the first end.
b - [out] Polar angle of the second end.
-
- Remarks:
TThe method returns polar angle (angle between radius towards a point and
radius in positive direction ox x axis) of the first and the second end.
HRESULT PassThroughPoint(double x, double y, int* result)
Parameters
x,y - [in] Coordinates of point to lie on this arc
result - [out,retval] - result code. See remurks
-
- Remarks:
TThe method modifies curvature of this arc so that the arc passes thourg the
specified point. Returns: -1 the modification is impossible geometrically, but
the curvature was been modified to the nearest valid value, 0 -
the arc already contains the point and there were no changes, 1 - the arc was
successfully modified
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