Mirror (kind of) plugin?


If I draw a part, left side as my other topic hereunder:

And then I want to draw another one, the right side… is there any feature or plugin as a mirror or kind of? (Instead of drawing another one)

There are a couple of native options. There’s Flip Along and the Scale tool with -1 as the scale factor. No need for a plugin at all. In both cases, copy the original and flip or scale the copy.

With Flip Along, select the component, group or geometry, right click on it and choose Flip Along and then choose the axis direction. Generally the correct axis to choose is the color between the parts. With Scale, you push a middle scale handle through the selection and type -1 then hit Enter.

See: Flipping, Mirroring, Rotating and Arrays | SketchUp Help



For those of us used to AutoCad, you can get various extensions to do this job, such as TIG’s Mirror. One thing you have to watch out for is what any mirroring process does to faces. They can get reversed inadvertently.

The native tools that @DaveR outlines work well but I find that it is often quicker to use the extension. Flip Along is fine if you are sure which axis you are working in. Using Scale at -1 is a better alternative and you should find that the cursor pauses briefly at -1 (watch the VCB) so you may not have to do any actual typing.

Keeping track of the axes has never been a problem for me. I wonder why some folks have so much trouble with it.

With keyboard shortcuts, Flip Along is faster than a plugin or Scale.

It’s because you cannot always see the axes, as here:

I guess I don’t have any trouble keeping track of the orientation I’ve drawn things in. And the common application for flipping as the OP was asking about is to make a right hand counterpart to an existing object on the left. If you pay attention to the color of the line trailing the cursor as you move the copy, you would know the orientation.

It’s good that TIG wrote his Mirror plugin but as with other things in SketchUp, it’s worth learning what the native tools can do before immediately looking for a plugin.

Hi Guys and thanks for your help. I used Flip Along and it did exactly what I wanted!


1 Like

Fair point. But to use Flip Along for this purpose, you generally have to make a copy first, move it an arbitrary distance, then use Flip Along, then Move to line up, don’t you? Mirror does all that in one go.

Out of interest, what shortcuts do you use?

Not necessarily. I usually place the copies exactly where they need to go and then flip them.

1 Like

Maybe it’s a picky point, but there is a technical difference between flip along or scale -1 and “mirror”: mirror means create a copy at the corresponding location on the opposite side of an identified mirror plane. For flip along and scale -1 the plane is implicit and you can’t specify it.

Actually, for Scale,-1, you can specify it with a mirroring line :wink:

As always, Dave, you amaze me! Could you please explain in words how you set the mirror line? Do you mean you include an extra item in the component at the desired mirror location, here the midpoint of the chair?

The “mirror line” is simply a guideline. In this case I placed it on the ground plane at the center line of the chair using inferencing to find that location. It may not be obvious in the GIF but the guide line is selected along with the leg, armrest and corbel for the scale operation. So in this example, it’s 3 components and the guideline that are selected.

The same thing works for the back slats.

With TIG’s Mirror:

Of course you still have to have something to identify where the mirroring plane is and on a model like this chair, it can be difficult to find that without some added thing like the guideline.

1 Like

I admit that I hadn’t thought of including a centreline in the selection when using scaling like that. Useful.

Again, being picky, it does mean setting up a construction line and including it in any selection, all of which would have to be taken into account in any time & motion study.

I do have a slight beef with @TIG’s extension for my own use. It asks whether you want to erase the original selection with the default being yes. The default I would prefer is no. Better still, I would like to see a toggle or modifier that controls this rather than another interaction before completion. It’s a small beef though.

We have this in our beginners course for several years.

Scale with - 1, or scale with Ctrl key to do ‘from center’ then type - 1 are my preferred method.

Otherwise I have TIG’s mirror as @simoncbevans mentioned short-keyed with Shift+m

Jack, that’s interesting but in my view does not qualify as a single MirrorScale operation. It is really two separate operations: the copying to allow reinsertion later and the scale to do the mirror image.

Now what would be nice is to add, say, the Ctrl key so that when you mirror, you leave the original where it is. One operation.

Here’s something based on @MikeWayzovski’s last post. When you are mirroring along an existing plane, you don’t need a construction line. It is essentially the same set of operations but in a different order. I wonder whether Mac users could use Automator to do this in one click?

Only works with Groups and Components, of course.

Actually, it works with loose geometry as well…

in the mirror tools that I know of, you would always have to select a mirror plane, sometimes with three clicks, if there isn’t any. Also,you would have to choose wether to ‘keep the original’,having shortcuts for paste in place is a ‘lifesaver’:grinning:

1 Like