Tangents to an ellipse

[whitelynx]

I'm trying to duplicate this sketch in CQ so I can extrude it:

I can make the ellipse and the bottom edge fine, but I haven't figured out how to create lines that are tangent to the ellipse.

result = (
    cq.Workplane("XY")
    .ellipse(30.5, 20.5)
    .moveTo(-20, -32)
    .lineTo(20, -32)
    .close()
    .sweep(cq.Edge.makeLine((0, 0, 0), (-0.30 * 60, -0.10 * 60, 60)))
)

Is there a way to create lines that are tangent to a given edge?

The only options I've come across so far are:

• use those angle values to make an ellipse arc, and then attach the endpoints to the bottom line
• extrude as above, and use .hull() to make a convex hull around the two pieces

Is there a better option, or would one of those be the best approach?

[adam-urbanczyk]

You could try with https://cadquery.readthedocs.io/en/latest/sketch.html#constraint-based-sketches

[whitelynx]

Aah, thanks! I had looked at those constraints before, but didn't notice until re-reading them that the angle constraint constrains the angle between the tangents, so I should be able to just set an angle of 0. I might try that!

In the meantime, I did it by just using an ellipse arc, and got it close enough that I don't really see a discontinuity in the surface.