Ease In and ease out

General Moho topics.

Moderators: Fahim, Distinct Sun, Víctor Paredes, erey, Belgarath, slowtiger

Post Reply
User avatar
strider2000
Posts: 445
Joined: Sat Mar 07, 2015 5:14 pm
Contact:

Ease In and ease out

Post by strider2000 » Thu Feb 22, 2018 1:25 am

Sorry if this has been answered before. If it has, I couldn't find it, so please feel free to just point me there.

This is a question for the animation pros :) Typically I use the smooth and step interpolation for most things, however I was just playing around with ease in, ease
out and ease in/out. I've used them before, but haven't analyzed them very much.

I know how to use bezier or add my own keyframes to get whatever interpolation I want, but I just wanted to see what the animation pro's think about "Ease In" and "Ease Out".

I've created a little video here


They don't look that good to me ("Ease Out" in particular), but I'm in no way an animation pro, so maybe I just don't understand, which is why I'm asking.

So here are my questions, assuming you set interpolation on keyframe 1 and your moving to keyframe 2.

1) Are the names in the right order?
Based on the Animators Survival Kit (expanded edition pg 38), I thought that "Ease In" would appear slower as it approaches the second keyframe. Conversely I expected "Ease Out" to appear slower as it leaves the first keyframe. This seems to be the opposite of the behavior I see.

2) How _should_ they compare to linear?
I would have expected "Ease In" to match "Linear" on the first half of the motion and "Ease Out" to match "Linear on the second half of the motion. My thought is that the middle key frame would be the same for all. However, I can understand if the motions don't exactly work that way. Rather than having a linear portion in each, it looks like "Ease In" and "Ease Out" are just variants of S-curves. I'm guessing that this is a limitation of the software, but with bezier curves I would have expected a bit better match.

3) Is "Ease Out" the most problematic?
Even if the names are not correct, and I just allow for that, it seems like "Ease In" is a fairly reasonable approach. But "Ease Out" seems pretty messed up, because it's faster then "Ease In", in both the beginning and the end :o It basically seems like it should be quite a bit slower at the end.

I realize this is a bit theoretical or just a convenience point, because we can achieve whatever we want with different approaches, but I'd appreciate some insight as I try to learn a little more about proper animation.

Thanks for the input.

Edit
Well, I did just see a problem with bezier :( If I move the key frames the handles don't move in the way I'd expect. Meaning, if I want to shorten or lengthen the time I have to redo the bezier handles in the motion graph (at least that's the best I've found so far). In case people are wondering, I was trying to animate a hang glider flying in the air. I want it to swoop down. I have a fix of sorts, use a two bone rig with independent angle for the second bone. Maybe there's a better way, but it would be nice to have "Ease In" and "Ease Out" not compress at both ends. If anyone knows a solution to that I'd appreciate the insights.
My new website (just getting started) | M1 Characters for Moho
hayasidist
Posts: 2221
Joined: Wed Feb 16, 2011 8:12 pm
Location: Kent, England

Re: Ease In and ease out

Post by hayasidist » Thu Feb 22, 2018 12:41 pm

FWIW - I think ease-in / ease-out are correctly named in Moho BUT not everyone does: https://medium.com/@gordonnl/ease-in-or ... 9a0969042e (**warning** offensive language in that referenced article)

As you've used layer translation, if you have the layer transform tool active you can see the "blue line" that shows not just the translation but also the intermediate positions at each frame. What this shows is that the motion curves for ease in, ease out and ease in/out are different but maybe not as markedly so as you'd maybe want. You might try a few screen grabs to enable comparisons.

I'll try a few observations / experiments (when time permits) on the internally held interpolation parameters [for any scripters watching who might want to leap in here: especially v1 and v2] for those three interpolation types (and Bezier) to see if they materially affect the shape of the curve.
User avatar
strider2000
Posts: 445
Joined: Sat Mar 07, 2015 5:14 pm
Contact:

Re: Ease In and ease out

Post by strider2000 » Thu Feb 22, 2018 1:16 pm

Thanks hayasidist. I can see how the names could be reversed from what I expected and it did seem t hat the industry uses them more than one way, so everyone's input is definitely appreciated.

Sorry about not grabbing the path. I did look at the paths, but didn't think about adding a pic. I've added one now for "Ease Out". I'll add others as I have a chance.

Note in particular that frames are compressed near both keypoints. In a different article (I'll look for the link) Greenlaw mentioned that Ease In/Out was just a stronger S-curve than smooth. I agree, and notice that Ease In, Ease Out, Ease In/Out, smooth are all S-curves (compressed on both sides, so they're all Ease In/Out variants). This means none of them have close the closest spacing at one end and the largest spacing at another. That makes it impossible to connect two key frames together with the fastest motion at the middle key frame... as far as I know, without using bezier.

Image
My new website (just getting started) | M1 Characters for Moho
hayasidist
Posts: 2221
Joined: Wed Feb 16, 2011 8:12 pm
Location: Kent, England

Re: Ease In and ease out

Post by hayasidist » Thu Feb 22, 2018 5:08 pm

I had a look at the interp params for ease in / out /in-out -- it looks as though they are set at default values - i.e. not used - so the curve shape can't be adjusted. It could be a good addition if we had editable curves - it has been mentioned before -- but maybe now's the time?

on the subject of timing paths - which is sorta what you're saying about "fastest in the middle" - have you seen my follow path script? http://lostmarble.com/forum/viewtopic.php?f=12&t=25384.
User avatar
strider2000
Posts: 445
Joined: Sat Mar 07, 2015 5:14 pm
Contact:

Re: Ease In and ease out

Post by strider2000 » Thu Feb 22, 2018 6:11 pm

hayasidist wrote: have you seen my follow path script? viewtopic.php?f=12&t=25384.
No I haven't. Thanks hayasidist. I'll check it out.
My new website (just getting started) | M1 Characters for Moho
Post Reply