Changing speed of motion path on same obejct

Hi everyone, 

I need to simulate the speed of light slowing down as it moves from a vacuum through an object and back out into the vacuum. In the attachment, the pink line represents light. I set a motion path to the object (blue rectangle) but now I need the same pink line to slow down as it moves through the rectangle, then speed back up again as it exits back into the vacuum. The way it was originally set up was with two additional pink lines with their own motion paths but that look was choppy and didn't work for the client. I have no idea if this can even be done. Can anyone help?



11 Replies
Steve Gannon

Hi Lynn,

The attached still has a slight pause in the middle but maybe it's an improvement on the version you mentioned where you used multiple lines.

In the attached, I animated the line midway, using a slow ease out. Just as that animation finishes, the line is replaced with a duplicate except the duplicate line has an animation with a slow ease in.

Lynn Hauser


I was able to get the animation to work the way you described. The only problem is that there's a short "glitch" in the first movement. It's as if it's catching on something and pausing before it moves into the blue square. I can't seem to get rid of it. I tried deleting and reinserting but it's still there. I've never seen a motion path do that before. Is there a way to eliminate that? 



Tom Kuhlmann

Here's yours. What's interesting is that neither stop for me. The object hits the box and goes from fast to slow immediately. I played it on Chrome, Firefox, and IE11 and it was smooth in all three browsers.

What happens when it gets to the end. Does it stop before it speeds up?

Which browser are you using?

It's possible that your PC isn't processing the transition fast enough. I used to run into issues in the old Flash days when we had some animations and transitions. It taxes the processor to calculate the movements. Some PCs would have noticeable changes.

I have a newer system with lots of RAM and an SSD. I just looked at my rendering % when running the slide with animation. It went from 1% to almost 15% for the time it took to go slow.

With a different system, that percentage could be much higher. In that case, you may experience a little stutter as it kicks into gear.

Lynn Hauser

That's weird. I'm using MS Edge but also tried it in Firefox and Chrome.
The latter had the least noticeable pause but it was still there.

The motion going out of the box is smooth, just like it should be.

I'll go back to the client and explain.

I may end up using the source PPT slide the includes this animation and
make a screen cast of it. Glad I attended the webinar last week. This will
be the first time I've ever tried it.

Thanks so much for all your help. Have a great weekend.