Transform.Mirror - how to make a copy?

So I am drawing symmetrical profiles (in the x and y axis) in vb.net and want to mirror them. The problem is, I cannot figure out how to make a copy when mirroring.

I can get the transformation to work, I just can't copy it.

I've tried a couple of different things. I've added each transformation to arrays and lists, but this doesn't work. I tried assigning the transformation at each step to outputs, still nothing. See code below (not actual code, just an outline of what I am doing)

Dim section as New Polyline

add point

etc.

Dim xMirror as New Transform

xMirror = Transform.Mirror(plane, xVector)

yMirror = Transform.Mirror(plane, yVecotr)

Dim list as New List (Of Polyline=)

list.Add(section)

section.Transform(xMirror)

list.Add(section)

section.Transform(yMirror)

list.Add(section)

section.Transform(xMirror)

list.Add(section)

A = list

Each polyline is added, but it looks like the transformation reads back up on the code.

Simple question, how do I mirror a copy?

Replies to This Discussion

Permalink Reply by Matthew Owens on September 6, 2012 at 12:43pm

OK. I just figured out one way to do this, but it seems a bit sloppy. I would still like to know if there is a better way to do this...

Dim crvA as New Curve

Dim crvB as New Curve

crvA = section.ToNurbsCurve

section.Transform(xMirror)

crvB = section.ToNurbsCurve

This seems very inneficient.

The following does not work:

Dim plA as Polyline

Dim plB as Polyline

plA = section

section.Transform(xMirror)

plB = section

Any input on this is greatly appreciated.

Matt

Permalink Reply by David Rutten on September 6, 2012 at 1:18pm

Transformations always affect the object they are called on. So if you want to transform a copy, then you first need to create a copy, then transform it:

Dim crvCopy As Curve = originalCurve.DuplicateCurve()

crvCopy.Transform(xMirror)

Don't use ToNurbsCurve to create a copy as you may lose information that way.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Matthew Owens on September 6, 2012 at 3:28pm

What about polylines? There are no Duplicate methods.

I could use a polyline curve, or a polycurve, but I don't know how to draw those! They require those strange things called IEnumerables. Not sure how to use those, although I am certain they are terribly useful...

Permalink Reply by David Rutten on September 6, 2012 at 4:39pm

Not all types can be duplicated in the same way. Polylines are nothing more than a list of point3d structs with some extra methods on them. You can create a copy using the copy constructor

Dim copy As New Polyline(originalPolyline)

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Matthew Owens on September 7, 2012 at 8:50am

Wow, that is a lot more simple than what I was going to do!

Thank you!

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