Hi Jörg, you're running into a bug there that happens with Offset.

The unwanted grid snap behavior happens because Offset actually calculates a totally new plane for the mouse to snap on to which it derives from the object. That's so that you can do offsets on any kind of planar object that might be at some different angle to the actual view's drawing plane.

Like for example if you draw a circle and then rotate it around in different views so that it is not aligned with the view orientations you can then still use Offset on it and the mouse for the offset pick will track in that circle's plane, not actually in the view plane.

So anyway to support that type of offset where it works on any kind of planar object, the offset command derives a snap plane from the input curve and the origin of that plane (where the grid snap will actually be based off of) will be at the centroid of that curve instead of at the construction plane origin.

I've added that to my bug list to fix up in the future - it should be possible for me to look for the case where the curve's plane is parallel to one of the view planes and then use the construction plane origin for those cases.

In the meantime to solve your problem you can instead draw a single point snapped on to your desired target grid location (It's under Draw curve > More > Pt), and then snap on to that point with an object snap inside the offset command and it should give you your desired result.

Let me know if you still have any difficulty getting the result you need with the alternate method.

- Michael

Hi Jörg, here's a bit more explanation on why that happens.

If you load the attached 3DM file you can see it has a curve in it, and although the curve is itself planar it is rotated around and not aligned with any of the Top/Front/Right views:



If you run offset on this curve you'll see that it will offset ok and when you move the mouse around you'll see that your mouse point is tracking along the plane that curve is in.

The origin of that tracking plane is the centroid of the curve's control polygon, and that origin point is what gets used for grid snap too.

So basically in the Offset command you end up using a different grid just for the duration of that command than the grid that you see inside of the viewports. Hope that explains the mysterious grid snap behavior! But like I mentioned I should be able to improve this in a future release of v3 so that it will look for the case where the curves are actually parallel to the view directions and use the construction plane origin for that particular case so that it will then grid snap onto the same grid lines that you see in the view.

- Michael

Hi Michael,

thank you for your explanation and the attachment.
I'm playing around with Moi without a concrete goal. So the "Bug" isn't bad for me.
The workaround works good for me and i'm still learning to generate/create a clean mesh in Moi.

That the offset is following the orientation of the spline, is a nice feature.
An "check box" to set the offset to planar. Perhapf it would be a possibility.

I understand that you want to keep Moi as clear as possible :)

Another question: Are there shortcuts for moving, scaling an rotation?
Or i can define it by a script?

Thanks for your quick help.

-->Jörg

Hi Jörg,

> That the offset is following the orientation of the spline,
> is a nice feature.
> An "check box" to set the offset to planar. Perhapf it
> would be a possibility.

Actually in the case that I posted, the offset result is a planar curve - it's just that it is in the same plane that the starting curve is actually in.

It would actually make a weird non-planar type of result if it tried to offset the curve in some other direction than its own plane...


> Another question: Are there shortcuts for moving, scaling an rotation?
> Or i can define it by a script?

The edit frame is the main shortcut for that - that's the 5 grips (4 corner ones for scaling and one for rotation) that surround the current selection automatically, which you can see in the 2D Top/Front/Right views (and the 3D view too if the object itself is planar).

See here for more info on how that works:
http://moi3d.com/2.0/docs/moi_command_reference11_German.htm#editframe

And the shortcut for movement is to just directly drag on an object, that will move it around.

There are also alternate transformation commands you can find on the Transform palette on the side pane - those can sometimes be useful for numeric control like if you want to scale from a specific origin point by a numeric scale factor. If you find yourself using those other transform tools a lot, it is possible to set up shortcut keys for those using the Shortcut Keys section of the Options dialog. You need to put the English name of the command in for the command part, so you would use these names for the commands column to set one of those up:

Move, Copy, Rotate, RotateAxis, Scale, Scale1D, Scale2D, Mirror

There is a list of all the command names for setting up shortcut keys here:
http://moi3d.com/2.0/docs/moi_command_reference11_German.htm#shortcutkeys

Hope that helps!

- Michael