PowerPoint Pendulums: Hidden Pivots and Harmonic Motion

PowerPoint Animation

One trick I seem to be using an awful lot in PowerPoint recently is a hidden pivot. Yesterday my colleague Scott shared a video (link) he had found of a set of pendulums carefully created to produce a really elegant and beautiful display when you set them all off together. Of course it didn’t take someone long to say “Now let’s do this in PowerPoint”, which I’m assuming/ hoping was tongue in cheek.

However for some bizarre reason I felt like the best way to unwind after working on projects all day in PowerPoint, was to make another animation in PowerPoint…

…and, this was the result:

Compared to the original:

Once I had looked at the video, and accompanying description that conveniently included the details of how they got the pendulums to work, it seemed fairly easy to create the effect in PowerPoint. But that was only because I used hidden pivots, rather than going crazy with motion paths. When I tried to explain that I didn’t think the animation was particularly complicated, no one seemed convinced, so here’s an explanation of how it works.

Most of the cool animations in PowerPoint are anchored on the centre of the object you are animating. For some animations it doesn’t really matter where the animation is anchored, but for others, in particular the spin animation, the centre point is crucial. Spin always turns the object about the centre point, which is great for creating something like a turn wheel or cog. But this is less useful if you want to have something swinging, like a pendulum for example. However there is a trick you can use to move the centre point of an object.

1 - the problem 540

What you do is create a large shape centred where you want the new centre point to be, that covers the entire object you want to move the centre point for. Next you group your original object with the new shape, creating a new group with a centre point correctly positioned for spinning the original object.

2 - moving the centre point 540

After this you select the large shape you created and format it so that the fill and line colours are 100% transparent, and voila! You have something that looks like the original object you want to apply a swinging motion to, but with a centre point that lets you swing it with the spin animation.

3 - formatting the large shape 540

One word of warning, this can create large areas of transparent objects all over you slides, which can make it difficult selecting anything below it, so you might need to rearrange the order of objects on the slide to make edits to something else. Using the selection pane can make this easier.

Finally once I had the 15 pendulums ready to swing it was just a case of calculating the timings they all needed in order to have the correct number of oscillations in the minute the animation runs for. Unfortunately, I think PowerPoint can’t quite do timings precisely enough to make the animation look perfect, but I guess that is what physics is for in the real world.

You can download my PowerPoint file here and take a look at the file if you wish.

 

Latest comments

Nathan Burley on 22nd November 2013 at 3:55 pm said

Hey Chris,

This is a great animation – mesmerizing to watch!

I wonder if you could answer a quick question as I seem to be having trouble getting objects to spin around their central axis. I thought it was because I hadn’t aligned things correctly. I tested this by creating a plain circle and spinning this, but I found that the circle appears to spin around a pivot which is slightly off center…. completely stumped as to why this would be. Any ideas?

Thanks!

Chris Korek on 22nd November 2013 at 5:20 pm said

Hi Nathan,

Thanks for the comment!

As for the off centre spin, I’ve definitely encountered it a few times when animating groups of objects, with seemingly no reason why it should be happening. One solution I’ve found is to set the transparency of the largest object in a group to 99% transparency (rather than 100%) you still cannot see it, but the animation seems to work better if the object isn’t entirely invisible.

Does that answer you question? Or are you encountering this with individually animated objects?

Chris

Nathan Burley on 25th November 2013 at 10:16 am said

Hi Chris,

Thanks for replying! Well originally, I was using a group of objects (three arc separated by 120 degrees – imagine the circumference of a radiation symbol) but these were merged so they should be acting as a single part. I figured I’d just misaligned the arcs so I redrew it until I was convinced it wasn’t me anymore. At which point I tested a circle (held shift down when i drew it to ensure it wasn’t an ellipse) and it’s happening on that too!

Struggling here… :(

Nathan Burley on 25th November 2013 at 10:24 am said

Just done a little more work on this and I’m not 100% sure but I think it might be down to where on the screen the shape is located. I’m wondering whether this is a trick of the display and widescreen or something similar. I know I’ve had frequent frustrations when I’ve lined something up when zoomed in only to zoom out and have it look slightly off due to the pixels etc.

Chris Korek on 25th November 2013 at 12:56 pm said

Hi Nathan,

I’ve definitely been there! One way to check if something rotating correctly is to draw lines around it so you can see if the animations move it out of the box and therefore off centre.

As for resolving the problem you’re encountering, I’m not sure why a single object is rotating off-centre, that is really strange. I don’t think I’ve ever had it with just a single object so don’t know what to suggest, sorry!

But with the grouped object, if you’ve rotated some of the component parts before grouping them, then sometimes their boundary boxes extend beyond the main shape you have. But unhelpfully it doesn’t take that into account when showing the boundary box of the group if you select it. That then throws off the centre point. To fix this you need to make the base shape larger to cover all of the extremes of every boundary box of every shape in the group. That should allow you to control the centre point, though it is a pain having to do this!

If that doesn’t work I find the solution of last resort is to cut the group and paste it as a picture, then crop into so that the centre point is where is needs to be. The problem with is of course that you lose editability and scaling it can cause problems, but sometimes needs must!

Hope that helps you solve this one!

Chris

Nathan Burley on 25th November 2013 at 4:19 pm said

Hi Chris,

Thanks for this. Yeh I didn’t believe it at first either. I drew a box around the circle to check it and it was definitely wobbling! Mind you, it’s not THAT bad.

I had no idea about the group bounding box so maybe that’s what’s throwing off my groups. Thanks for that, I’ll check that one out. I have done the image thing in the past too – needs must eh?!

Cheers again for all the help – I do appreciate you taking the time.

N

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