| | Describes a parabola in the plane (2D space).
A parabola is defined by its focal length (i.e. the
distance between its focus and its apex) and is
positioned in the plane with a coordinate system
(gp_Ax22d object) where:
- the origin is the apex of the parabola, and
- the "X Axis" defines the axis of symmetry; the
parabola is on the positive side of this axis.
This coordinate system is the local coordinate
system of the parabola.
The orientation (direct or indirect) of the local
coordinate system gives an explicit orientation to the
parabola, determining the direction in which the
parameter increases along the parabola.
The Geom_Parabola parabola is parameterized as follows:
P(U) = O + U*U/(4.*F)*XDir + 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,
- F is the focal length of the parabola.
The parameter of the parabola is therefore its Y
coordinate in the local coordinate system, with the "X <br>
Axis" of the local coordinate system defining the
origin of the parameter.
The parameter range is ] -infinite,+infinite [.
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1.6.3