| | Describes an ellipse in 3D space.
An ellipse is defined by its major and minor radii and,
as with any conic curve, is positioned in space with a
right-handed coordinate system (gp_Ax2 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.
The origin, "X Direction" and "Y Direction" of this
coordinate system define the plane of the ellipse. The
coordinate system is the local coordinate system of the ellipse.
The "main Direction" of this coordinate system is the
vector normal to the plane of the ellipse. The axis, of
which the origin and unit vector are respectively the
origin and "main Direction" of the local coordinate
system, is termed the "Axis" or "main Axis" of the ellipse.
The "main Direction" of the local coordinate system
gives an explicit orientation to the ellipse (definition of
the trigonometric sense), determining the direction in
which the parameter increases along the ellipse.
The Geom_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 [.
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1.6.3