# Tangent object snap

I have just discovered that tangent object snap works only if the curve is on the construction plane. Other object snaps work on all curves.

Can you elaborate on how exactly it would work if the curve is not in the CP? What kind of task would require a tangent snap to a curve thatâ€™s not in the plane which will contain the new geometry?

Hi Andrew - that is not the case - the curves must be in the same plane however, or no tangent exists.

-Pascal

Tangent object snap is confusing when you draw a line from a point to a curve. If the point elevation is different than the curve elevation, tangent fails, and the reason for the failure is not obvious. There are two ways to fix the problem:

• display warning near the cursor when tangent fails
• project all coordinates on the construction plane before drawing tangent line and change elevations of the line ends

Warnings are not displayed when an osnap â€śfailsâ€ť, it simply doesnâ€™t snap. That means it canâ€™t find a point which corresponds.

I would not want Rhino to alter my geometry arbitrarily like thatâ€¦

â€“Mitch

I think Andrew raises good point, however. If the point a user is trying to make tangent from is even a little bit out of plane and the user doesnâ€™t realize it because he thought he put it on the plane, he might try 15-20 times to get it to snap before he starts reaching for the cricket bat to discipline the computer. I just wish I had a good idea about how to help him realize whatâ€™s going on (or not going on).

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