Calculate multiple objects in a circle in Illustrator

 

When you are drawing or designing in Illustrator you probably at one time or another need to put multiple objects in a circle. This is basically very easy by using the Rotate tool. Click somewhere you want the center of rotation to be and drag the object while you hold the mouse. Repeat this process over and over or simply do Object > Transform > Transform Again or even Command + D.

This method is fine when no precision is needed. But lets say you want to make a drawing of a clock or a watch or something similar. There you might want to put one object twelve times in a circle to mark every five minutes and even have another object to indicate every minute sixty times in a circle. And to make this a bit more complicated, maybe you want to be able to edit those objects after you have placed them in a circle without having to do everything over again if you need to change.

This is all very doable in Illustrator. I am going to walk you through three different methods and point out some advantages and disadvantages in every one of them. In the end I am going to show you a calculator I made to help you make this very precise.

The first method is very similar to the one I mentioned in the beginning but we can be much more precise with very little extra effort.

First, drag one horizontal and one vertical guide lines into the artboard. Where they cross will be our center of rotation. Draw your object at the top and keep the object centered on the vertical guideline.

While the object is selected, choose the Rotate tool by hitting the R button on the keyboard. Hold down the Alt/Option key and click once where the guidelines cross. This will bring up a dialog box where you can type in the degree you want the object to be copied by. You might know that twelve objects need to be 30° apart but if not, type in 360/12 and hit the Tab key once to confirm. Illustrator will instantly calculate the degree for you. Having the Preview on shows you the movement and when you hit the Copy button the first copy is made. Hold down Command + D until the circle is filled. Great isn’t it?

The disadvantages here are that holding down Command + Z will not undo in the same way or speed as Command + D made the copies. You have to click for every object made if you change your mind or have made some mistakes. Which is fine for 12 objects maybe but not 360. And secondly, if you want to change the shape of the objects you have to do this all over again which can be a pain. It is therefor nice to make the 12 objects on a separate layer and the 60 objects on another to easily remove any parts you like in one go. But this is the nice and easy way to go when you only need to do this once in a while.

The second method is exactly like the first one, except that when you have placed the object at the top you drag it to the Symbols panel and then do the rest. This means that what you rotated are instances of that symbol in the Symbols panel and thus can be edited. You can select the ones you want to change and choose a different symbol or you can make a new object and Alt-Drag it over the symbol you just used and all will be replaced.

This is a clever and useful way to use Symbols but still it’s not the perfect way if lets say you are a professional watch designer.

The third method and in my opinion the best, is to use the Transform Effect. Still, it is missing some vital controls but to overcome that I made an online calculator to overcome its shortcomings.

Select your top object and go to Effects > Distort & Transform > Transform… Start by checking the Preview box The big dialog box allows us type in how many copies we need. In our case we need 11 copies. Then down left we can let Illustrator calculate 360/12 to get 30° (or 360/60 for the minutes etc…) By now we can see all our instances in one bundle centered together.

Now we need to move the Horizontal and Vertical Move sliders to add the spacing between the objects and this is where the problem begins. Problem one is that there is no obvious way to determine the overall width of our circle nor the radius. I have asked some of the folks who specialize in Illustrator and how to set this the way that the 9 and 3 objects and 12 and 6 objects align (I am referring to the positions of the objects). The answer has always been: Put the same numbers into the Horizontal and Vertical values.

This is true, yes, but playing with positive and negative numbers always turns out that the original object is in one of these positions: 2, 5, 8 and 11.

In this example setting four objects with the values to 20 and 20, positive and negative, the instances go from position 8 and we would have to rotate the object itself also afterwards by 120° to straighten things up. Besides, as you see the objects here are placed where I planned to have as the position 12 and finding the correct position would be a pain again. And it stretches out of my artboard.

Not totally unusable but it could be far better. The way Transform Effect works, you can edit the original object and the instances will change according. But it is not so easy to work with even sides at 30 degrees when the object is always tilted. Besides that, making the objects fill a circle of a certain size can only be found by trial and error as far as I can see.

I still want my main object to be placed at the top for easy editing and I want to be able to set the exact size of the circle. This is where the IllustratorCircleCalculator comes in. The calculator uses the same parameters as you use in the Transform Effect dialog box but adds the diameter of the circle you want to use as a main element in the calculation. And everything fits perfectly and you can freely edit your one top object and all the instances update on the fly.

All you have to do is to fill in the diameter of the circle and the number of objects that you want on the circle and you get the Horizontal and Vertical values you need to fill in to make everything fit.

I am not sure if anyone cares to know the math behind this calculator but here is a picture which I used when I was figuring this out.

The V and H on the red triangle are the measurements we are after. Knowing length of the longest side, L, and the degree of the sharpest corner, V is the COS x L and H is SIN x L.

The length of L is two times the shortest side of the brighter green triangle which has half of the degrees to the first instant.