Thnaks for the answer.

when you create the line as you did. it works. but if you take a line and move if in the surface afterwards, it does not.
ideally, i would like to lock the displacement in a plane (without having to create it each time).

Hi Hadri1, the point picker will not try to calculate surface/curve or surface/surface intersections dynamically like that because those calculations can be time consuming operations on more complex surfaces.

If it tried to generate all possible intersections like that automatically then trying to draw a line on a complex model would likely consume significant CPU as you moved the mouse around.

But there are a couple different ways you can get that result.

One is before moving the endpoint, select the line and the plane and run the Construct > Curve > Intersect command. That will generate a point object at your desired location and then you can drag the endpoint onto there and get a "pt" snap.

Another way is to set the Construction Plane. Unlike regular geometry, curve intersections with the construction plane are calculated and you can get a "CPlane Int" object snap where you want without leaving the 3D view.

Click View > CPlane, click once on the plane to set the base point and then right click to accept the default rotation. After that you will get a "CPlane Int" snap point where you want.

To restore the cplane back to world coordinates you can use View > CPlane > "Reset CPlane" button, or right click View > CPlane, or set up a shortcut key with this:
script: moi.view.resetCPlane();

- Michael

And yes if you move the point in one of the 2D ortho (Top/Front/Right) views instead of the 3D view the point will stay at its z/elevation level when you move it.

That doesn't happen automatically when dragging points in the 3D view so that you have more freedom to construct non-planar objects in that view.

- Michael

Also a third option is select your point, run Transform > Move, and then drag out a construction line from your selected point onto the line, there will be a "Perp" snap at your desired target point.

- Michael

Hi Michael,

Thank you for your answer.

i liked the idea of not having to create and extrude each time you want to have a displacement in a Given plane, so using a CPlane is a great idea.
unluckily, i created the Cplane, but i am not able to snap onto the intersection between the Cplane and the line.
i am using Moi 4.0.

A video has been added in the same link.

Hadri1

Hi hadri1,

> unluckily, i created the Cplane, but i am not able to snap onto the intersection
> between the Cplane and the line.

Your Cplane isn't working because you've got the "Align to objects" option turned off when you place the cplane onto the plane's corner point.



When this option is disabled then only the origin point of the cplane is modified and the x/y/z axis directions remain in world orientations.

To get your cplane intersection working you need to turn on the "Align to objects" option when setting the cplane so the z axis will be normal to the plane, like this:



If it looks like this (below) as in your video it still has world axis directions for the construction plane's x/y/z axes.



- Michael