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What is up with triangles in Illustrator?

Forum|Forum|5 years ago
November 12, 2020
7 replies
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What is up the basic triangle in Illustrator? This has bothered me for years.

Its default center point is always off compared to other shapes. It is never actually center. Which throws then throws off the rotation.

It also doesn’t act the same as other shapes with the free transform tool.

If you use a tringle as the shape for in this tutorial the results are quite different compared to other shapes.

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Correct answer Doug A Roberts

Yes. I messed up really reallu bad. Not only did I rush the whole thing, but I didn't proof anything.

For that I humbly apologize. There was no realy excuse.

Here is the link - https://www.youtube.com/watch?v=ceufglnNPKI&t=203s

As per @Kurt Gold 's pointer later in this thread, you need to keep the triangles as live shapes to have them transform around their geometric centre rather than the bounding box centre. In one of the first steps there, the presenter uses a zig zag effect, then expands it -- making it no longer a live shape.

If you create the second triangle before you expand them both (scaling with 'Scale strokes & Effects' checked in the Transform panel), your smaller triangle will scale to its geometric centre.

Kurt Gold

Community Expert

Ton,

Guides do snap to them if you enable the centre point button in the Attributes palette. Smart Guides will then at least partially snap as well.

There are some unfortunate limitations, though.

Ton Frederiks

Community Expert

I see, that makes it a little more useful (I edited my comment).

Kurt Gold

Community Expert

Recent versions of Illustrator actually do show the geometrical centres of triangles and (some) other polygons as long as they are live (shape) polygons.

In case your triangles are not live shapes, you can try to convert them with the Object menu > Shape > Convert into Shape command.

Doug A Roberts

Community Expert

So they do! It's easy to forget to check what you remember every so often.

Jacob Bugge

Community Expert

Oppel,

There is no way that the centre of the Bounding Box can coincide with the centroid/geometric centre of a polygon with an odd numer of sides.

https://en.wikipedia.org/wiki/Centroid

There is no link to the tutuorial, but I believe that it may have incorporated a nofill/nostroke circumcircle forming a Group with the triangle, in which case you can just rotate freely in any way you wish.

And what Steve said, apart from the word stupid: she likes to challenge us and keep us on our toes.

Steve Fairbairn

Inspiring

Perzackly. Silly old Illie.!

Jacob Bugge

Community Expert

Oppel,

In addition to what Doug and Ton said, to get just a clearly visible centre (even when unselected) to click for your rotation, you can select the triangle and Alt/Option+Ctrl/Cmd+J or Object>Path>Average with the default Both, with Round Cap in the Stroke palette; without the Round Cap you will need to rely on your friends Smart Guides to find it, but you know where it is so you can also use it as visual practice.

As with the exquisite circumcircle (by 佐藤浩之, Satō Hiroyuki), you get an additional path which can be deleted when you are sure that you have finished rotating.

Steve Fairbairn

Inspiring

Hi Jacob. There's also the old trick of adding anchor points and drawing lines from the corners to the opposite anchor point. Where the lines intersect is the geometrical centre. You can convert those lines to guides and group the to the triangle so that you can always find that centre again.

Jacob Bugge

Community Expert

Hi Steve, so great to see you.

Ton Frederiks

Community Expert

As Doug mentioned, the rotation center is the center of the bounding box.

This script "Circumcircle.jsx" shows the real center by drawing a circle around the object.

https://github.com/Shanfan/Illustrator-Scripts-Archive/blob/master/jsx/Circumcircle.jsx

OppelWoWAuthor

Known Participant

I have done something similar to get the center of a tringle.

That does not help with help with doing the tutorial.

Doug A Roberts

Community Expert

The centre point of a triangle in Illustrator is the centre point of its bounding box. This is true for all shapes -- not noticeable in things like ellipses and rectangles, where the centre of the bounding box and the centre of the shape coincide.