Hi Pilou - any 4 points will make a curve that is made up of 4 different ellipse segments I think, not just one single ellipse.

Here is one trick you can use to deform a circle by 4 corner points, which is to create a trimmed surface and then move the surface points around.

Start by drawing a plane (not a rectangle, but a filled-in plane from Draw solid / Plane):



Now draw a circle centered on the plane:



Trim the plane by the circle, then select the resulting disk surface and turn on control points with Edit / Show pts:



Now the points can be adjusted and the circle trim curve on the surface will deform as the underlying surface is stretched around:



When you're done, you can extract the trim curves as a regular curve object by selecting it and using Edit / Copy then Edit / Paste.


> There is not function "Ellipse tangent" in the future?

Often times these kinds of calculations are more difficult with ellipses since there are more variables to define, like 2 different radius values instead of a single radius. This makes for a large number of different proportioned ellipses that can fit tangent to 2 curves.

- Michael