Hello

I was wondering how I would go about making an arc that followed an elliptical curve, or how to cut an ellipse into sections? The arcs I am creating have a sharp beginning and end, that is if they are mirrored they make the shape of an eye (hope that makes sense).

Kind regards

Jon

Hi Jon, the arc from center point command does have an "Elliptical" checkbox option that you can enable to help with that:



When that option is enabled, you will draw an ellipse segment between the start and end point rather than it just taking the angle between those 2 points.


If you have a full ellipse that you want to cut up into sections, you can use the Edit > Trim tool to do that - that's the tool for cutting curves up into pieces.

You can either draw in some lines to use for the cutting objects, or you can click the "Add trim points" button inside of the Trim command to pick some points on the curve for where you want to cut it.

See the help file here for more info on Trim:
http://moi3d.com/2.0/docs/moi_command_reference4.htm#trim

- Michael

Hi Michael

thanks again.

King regards

Jon

Hi Jon, also re: sharp when mirrored - if you want your elliptical arc to have that kind of sharpness when mirrored you would want to pick the points of the arc somewhere other than directly along the x or y axis directions.

For example if you draw an arc that's a full quadrant like so:



That kind of shape will be smooth when mirrored.

If you make the arc some smaller section of the ellipse instead of having the start and end at one of the quadrant points like this:



then that's the kind of a shape that will have a sharp corner if you mirror it around the x or y axis directions.

If you want just one side to be smooth and the other sharp, then put the side that you want to be smooth directly on the x or y axis direction and the other one not.

- Michael

And actually the way that it works is that the ellipse that you make will actually have the ellipse axis pointing towards the direction that you click the first point in.

So when you click the first point of the elliptical arc not on a quadrant point that means that the base ellipse that you're making an arc from is a rotated ellipse.

If you want to have an arc segment from a non-rotated ellipse then you would need to draw a full ellipse and trim it to get that particular kind of elliptical arc segment.

- Michael