Line From Center Extension

Dear @TheOnlyAaron, @matt_robison and SketchUp Community!
This is JPCodaLot (aka Doc. Frankenstein).

In Modeling Machine Parts Live with Aaron at 1hr. 50min. 8sec. Matt recommended an extension with the ability to draw a line from the center of itself. Not unlike the “draw rectangle from the center” feature added in SketchUp 2020. He then implored me - by name - to build it for him.

Let it be known that his request has been answered!
Lo and behold, here is the extension below and for now it is FREE.

The extension still has some rough edges and lose bolts but I am just dying to get it out there:
jpc_LineFromCenter - Signed.rbz (17.0 KB)


From center of what ?

Oooohhh! Gonna try this out!!

I’m so thrilled for this, that I think it’s barely worth mentioning it wasn’t actually me, but I want to take credit anyway.

Can we do this on a regular basis, make crazy demands in the live-modeling sessions and behold! A new extension cometh forth-ith!

Nice Doc, nice.

Any chance of explaining what this extension does without needing to trawl through the video?



Thanks @TysonK,
I am so sorry about the mix up.
Yes please, I would love to try more crazy extensions!
I will be ready in my secret lab to bring life to your great ideas.

I believe it was @matt_robison that made the comment. Regardless, I will be giving this a shot this week, and a shout out this Friday!

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Woah! It… Is… Alive!! Incredible work @JPCodaLot

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Here’s one for you then.

Architectural drawing frequently needs to establish a centreline or centrepoint between two other lines/points. There used to be an extension called Midpoint that helped with this.

So how would it work?

For points, I imagine invoking the command and then picking any two points in space to define the controlling parameters. Then the extension would place a marker (3D cross?) at the centrepoint with axes normal to the working environment. Ideally, this would be a species of construction line. In fact it could be three such lines meeting at the midpoint. That way, it is easy to delete it after use by clearing all construction lines.

For lines, something very similar. In this case you would select two parallel and coplanar lines and the extension would place a single construction line halfway between them. There would have to be a warning system if the two chosen lines were not parallel or were not coplanar.

In case it’s useful, what I tend to do for lines using native tools is to place one along one of the “founding” lines, then copy it to the other founding line, then hit /2. It’s pretty simple but a bit of a faff.


On reflection, maybe the lines don’t need to be coplanar, just parallel?

The link had a time index to bring you exactly to the place in question.

So also answering my own question …

Aaron needed to find the midpoint between 2 circles (holes) which were one above the other Y-wise looking down from above.

He had to draw (with the LineTool) a temporary vertical line between the outer vertex of one to the other, and then use a midpoint inference to draw a horizontal line denoting the center between the 2 holes.

I recreated the scenario, thinking that using an inference toggle lock, we should be able to do this natively. But it does not work natively.

Nice touch! I can’t tell you how many times over the years I’ve drawn a line to length and then moved it from the center point.
Thank you!

You are very welcome!
I have done the same thing too many times over.

In a related thread, I envisioned an extension that, behind the scenes, drew just such a line to provide a temporary midpoint inference, deleting it automatically at the end of the action. Such a line might look a bit like hidden geometry so you can see that it has been briefly created. I have no idea if such a thing is even possible!

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By definition, two lines parallel to one another ARE coplanar.

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Very handy! Thank you for sharing.

FYI the tool button icon did not load on my Mac, I get the splat face in the toolbar, could be my system. Still works great.

I am sorry about the toolbar.
I don’t have a MAC computer to test it on. Subsequently all my extensions are “Windows Only”.
The problem is that the toolbar icon is a SVG witch Mac doesn’t load.
I might try putting a PNG toolbar for Mac users like you.
Like I said:

No worries, still works great! I was just reporting back. Thanks

I was lazy in my terminology. By coplanar, I meant on the same axial plane (XY, YZ, XZ). Not sure if there is a neat single word for that. Coplanaxial?

There are many free utilities to convert a svg into a pdf that Mac SU will accept. Don’t use a png except if you support pre-2016.