
This task shows the various methods for creating conics,
that is curves defined by five constraints: start and end points, passing
points or tangents. The resulting curves are arcs of either parabolas,
hyperbolas or ellipses.
The different elements necessary to define these curves are either:
 two points, start and end tangents, and a parameter
 two points, start and end tangents, and a passing point
 two points, a tangent intersection point, and a parameter
 two points, a tangent intersection point, and a passing point
 four points and a tangent
 five points



Click Conic
.
The Conic Definition dialog box opens. 


Fill in the conic curve parameters, depending on the type
of curve to be created by selecting geometric elements (points, lines,
etc.).
 Support: the plane on which the resulting curve will
lie

Constraint Limits:

 Start and End points: the curve is
defined from the starting point to the end point
 Tangents Start and End: if necessary, the
tangent at the starting or end point defined by selecting a line



Selecting the support plane and starting point 
Selecting the ending point 




Selecting the tangent at the starting point 
Selecting the tangent at the ending point 


Resulting conic curve 

 Tgt Intersection Point: a point used to define
directly both tangents from the start and end point. These tangents
are created on the virtual lines passing through the start (end)
point and the selected point.



Using a tangent intersection point 
Resulting conic curve 

Intermediate Constraints

 Point 1, 2, 3: possible passing points for the
curve. These points have to be selected in logical order, that is
the curve will pass through the start point, then through
Point 1, Point 2, Point 3 and the end
point.
Depending on the type of curve, not all three points have
to be selected. 
You can define tangents on Point 1 and
Point 2 (Tangent 1 or 2). 
 Parameter: ratio
ranging from 0 to 1 (excluded), this value is used to define a
passing point (M in the figure below) and corresponds to the OM
distance/OT distance.
If parameter = 0.5, the resulting curve is a parabola
If 0 < parameter < 0.5, the resulting curve is an arc of
ellipse,
If 1 > parameter > 0.5, the resulting curve is a hyperbola. 




Click OK to create the conic curve.
The conic curve (identified as Conic.xxx) is added to the
specification tree. 
