| | Describes an ellipse in the plane (2D space).
An ellipse is defined by its major and minor radii and,
as with any conic curve, is positioned in the plane
with a coordinate system (gp_Ax22d object) where:
- the origin is the center of the ellipse,
- the "X Direction" defines the major axis, and
- the "Y Direction" defines the minor axis.
This coordinate system is the local coordinate system of the ellipse.
The orientation (direct or indirect) of the local
coordinate system gives an explicit orientation to the
ellipse, determining the direction in which the
parameter increases along the ellipse.
The Geom2d_Ellipse ellipse is parameterized by an angle:
P(U) = O + MajorRad*Cos(U)*XDir + MinorRad*Sin(U)*YDir
where:
- P is the point of parameter U,
- O, XDir and YDir are respectively the origin, "X <br>
Direction" and "Y Direction" of its local coordinate system,
- MajorRad and MinorRad are the major and
minor radii of the ellipse.
The "X Axis" of the local coordinate system therefore
defines the origin of the parameter of the ellipse.
An ellipse is a closed and periodic curve. The period
is 2.*Pi and the parameter range is [ 0,2.*Pi [.
See Also
GCE2d_MakeEllipse which provides functions for
more complex ellipse constructions
gp_Ax22d
gp_Elips2d for an equivalent, non-parameterized data structure
More...
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1.6.3