Mirror copying in SU

I often need to mirror copy something, often a bunch of groups or components in an assembly. I even have a plugin to speed things up. There are a number of ways to mirror something in SU but they all reverse faces (scaling doesn’t but you would have to apply that to each group within the assembly in turn). It’s a pain to have to go into each element and reverse faces (even with a plugin that speeds that up). I would like a facility that allows me to specify that a material applied to a group or component affects all faces, front and back. Alternatively, a plugin that not only mirrors but reverses faces at the same time. Does anything like either of those exist? Or is there a cunning way already built in?

Simon, what mirroring process are you using that reverses the faces? Whatever it is, you shouldn’t be using it.

Scaling with a factor of -1 is one way to mirror entities. Another is to use Flip Along. Neither of them reverse faces.

Generally it is unwise to leave back faces exposed, anyway.

Due to the nature of many of the projects I draw, there are many mirrored counterparts of components. I set up keyboard shortcuts for the various Flip commands to speed up the process.

DaveR, you are riding to my rescue once more!

The shortcut I use is a plugin called Mirror Selection. It works well apart from the reverse faces issue.

A section through a building often involves a mirror image. When I draw the various elements of a wall (cladding, battening, insulation, structure, etc.) I generally make each a group or component. I draw one half of the building and then use Mirror Selection to represent the other half.

Of course, I could use scaling or flipping on each individual element, but that would take a long time and nothing would then be in the right place. I guess I could also do it if I exploded all the elements first, but that would also defeat some of the object.

Any ideas?

As far as I know, TIG’s plugin Mirror doesn’t reverse faces. I use it frequently.

Get from Sketchucation Plugin Store.

Simon, are you mirroring 2D entities?

This confuses me. I guess I need to see an example of what you are doing exactly.

You should be able to use scaling or flipping on a selection of components/groups without exploding. there shouldn’t be any need to do it individually.

I think that is the one I use but it does reverse faces if the element is 2D.

2D entities, yes. If I am doing a section drawing, I make a section cut through the 3D model, use Make Group from Slice to create a 2D image, and then add the detail I need. Each element of a wall, say, might be represented by a rectangle, grouped to avoid inadvertent editing. When I have created each element of the section, I mirror it along the ridge line, say, to create the other side. I guess if I grouped all the elements and included a line at the centreline, scaling or flipping might work. I’ll try.

Could you make a simple example just before making the copy and send it to me so I can see what you are doing? From what I’m getting in your description, if there are no exposed back faces in the original, there should be no exposed back faces in the flipped copy.

I don’t have the problem you describe on a simple component - rectangle with blue face up on red-green plane.

I select the original, select the mirror plane (blue-green) with THREE pick points, and when I finish with the third click, the mirrored rectangle is the same way (blue face) up.

HOWEVER, if you only pick a line for the mirror, instead of a plane - e.g., the green axis for Mirror (two pick points followed by {Enter}), it will indeed put the rectangle white face up.

You can make the three point pick in ‘free space’ - just get the axis line colour showing after first and second picks before clicking the mouse button.

I attach an example which I took from a current drawing. The construction I want to copy is on the left. The mirror copied one on the right. Interestingly, some elements have a back face showing and others don’t. Not sure how that happened.

If I Group all the elements on the left and scale (or flip), it works fine, but I have to make a copy first and then move it into position. All extra work compared to mirror copy.

I believe there may be plugins to do some or all I want but I don’t like having too many bolt-ons to rely on.Example.skp (995.8 KB)

It looks to me like you are using Rotate/Copy instead of Flip.

Try this.

Select all of the left side and use Move/Copy to move a copy to the right.

Right click on the still selected copy. Choose Flip Along>Red Direction.

After flipping, move the copy into place.

You could also use Scale and -1 on the copy to create the mirrored version of the left side.

Mirror might be one worth having.

If I leave the geometry ungrouped (and not a component), and mirror even with a three point pick, I get inconsistent results - sometimes faces reverse as in your example, sometimes they don’t. When I first did it immediately after opening your Example.skp the faces reversed. When I did it subsequently, they didn’t. When I closed the drawing without saving, then reopened it, I couldn’t get the mirror to misbehave again.

But if I group or make component out of the loose geometry, then mirror that with a three point pick, it behaves properly - faces stay ‘up’ in the mirror.

Odd, I agree.

I see Shep got there before my reply was finished. He’s doing what I tried - and using a three point pick. That way, it seems to work fairly if not totally reliably.

John, do you get inconsistent results with Flip Along, too? I’ve never seen any problems like that using the various flip options.

I didn’t try Flip along, just TIG’s Mirror. And only got it to misbehave once. It’s never done that in years of using it, when I mirror components, and I don’t remember ever having a problem with mirroring loose geometry either. But I’ve always used a three point pick, as I couldn’t (and still can’t) quite work out in my head what it is supposed to do with ‘mirroring’ about a line.

I see.

Dave, that works I know, but if you have to do it often the combination of copying, flipping/scaling, and then moving seems very long-winded. A straightforward Mirror with option to reverse faces (or perhaps as the default) is what I was after.

Personally I find, Copy, Scale snap to -1, Paste in place works best for me.

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With a keyboard shortcut for flipping, it isn’t especially onerous.

TIG’s mirror plugin seems to only sometimes reverse faces. Maybe you can use it and orient the faces when needed. Or, use Rotate/Copy knowing that you’ll have reversed faces but then immediately use Reverse Faces from the Context menu to correct them.