...properly use "linear" interpolation?

[martin_mrt]

Hey there,
I am currently starting to animate more and more in Moho.
Coming from ae I find myself missing the option to set a whole bunch of keyframes to the interpolation mode linear (on arrival !).
Modes in Moho influence the space between the current and the next keyframe. But how can I have an Ease Out and a Linear in?
I'm aware that I could change all the keys to Bezier but that's very much effort if there are a number of keys.

For better clarity here are some ae screenshots of what i am missing in Moho:




How do you guys approach this? Any workarounds/methods to suggest?

Happy for any help and workflow advice!

[martin_mrt]

Here a similar situation in Moho:
Left key set to Easyin/out. Right Key set to Linear, but it is actually Ease in.
Is there a easy way to set them to "linear on arrival"?

[slowtiger]

Yes, this is a tricky one.

For a long time I thought that interpolation modes worked from the selected key onwards to the next key, not affected by anything before or after. This is obiously not true. Check this:

Create a layer with some content. Go to frame 1 and click with M tool to create a key (which is the same position as in frame 0) with smooth interpolation. Go to frame 50 and create a smooth key at a different position. You should see all inbetweens now, following an ease in/out scheme - as expected.

No create a third key just 1 frame after 50 and position it just a bit different. Surprise! The inbetweens 1 - 50 will now change to an ease in/linear pattern. Play around with the last key's position to see how that changes interpolation, also shift that key in time.

Now go back to frame 0 and change its position. Surprise! Inbetweens 1 - 50 will now show something like linear/linear.

Follow this and test with other interpolation methods. You will somehow be able to achieve your required result, but maybe end up with an additional key. I'd just go back one frame and make the last inbetween at 49 a key, too, then erase any "scaffolding" key after 50.

Usually I don't need this level of control for characters, but for very slow in/out moves of vehicles or camera this may be necessary.

[hayasidist]

yeah - smooth always has behaved that way ... much more about that here: viewtopic.php?t=37697 and in the linked post viewtopic.php?t=36006

[Greenlaw]

My understanding is that Smooth looks at the incoming curve and makes sure the outgoing side follows its trajectory. I might even call it 'the adaptable mode', and, to me anyway, it's what makes this mode so useful for character animation. Most of the time, I can just set it and forget it.

Smooth shouldn't be confused with Easing, Linear, or other modes, though, which have specific behavior. However, depending on what comes into Smooth, it can imitate these other behaviors.

When I need to get very specific about the shape of a curve, I just use Bezier mode. In fact, you can make Bezier do almost anything. I don't use Bezier often, though, because it requires manual adjustment, and Smooth usually does what I need.

I'll use Linear for anything 'mechanical', or when I'm setting up Smart Bones. In Smart Bone Actions, Linear can help keep multiple layers of animation keyframes in sync. When the action has more fluid or organic animations, I may switch to Smooth, though. When I'm unsure, I'll try both and pick whichever looks best for the situation.

I never use the Ease modes because they never seem to work the way I expect. Besides, I can usually get Smooth to do what I need for easing in/out, so I don't really consider using the Ease modes anymore. When Smooth isn't quite cutting it, that's when I switch to Bezier.

[Greenlaw]

... much more about that here: viewtopic.php?t=37697 and in the linked post viewtopic.php?t=36006

Thanks for posting this, Paul! I've seen these topics before, but it doesn't hurt to review this info.

[martin_mrt]

Thanks slowtiger for the detailed walkthrough. It game me an "aha moment"
I certainly understand now better how the smooth interpolation works!
Unfortulately it doesent work with the same value and a copied key. With rotation it requires to alter the value at least a tiny bit. On a rig I would have to find a way to go through at least the main bones and alter the value. (btw. tips on that welcome too! with translation strg + arrow works fine. For rotation i change the numeric value for very fine adjustment. I guess theres a better way...?) Its very good to know how it is possible! Thanks! If needed I can apply it and this information certainly helps me to get into key and curve juggeling in moho

Btw, smooth already became my go to interpolation and I agree with the comments here that it most of the time does what I want. for weighted eases eg. i freeze a pose between two keys and just push it closer to the one or other. makes more keys in the timeline which gets to me a bit, but i color those in a specific color to make that a bit easier XD hehehe

Thanks hayasidist for posting the other topics!
I read through them. I share the experience of the feeling that ease in and ease out is switched up.

I want to share a usecase where a "real" Linear mode would be helpful:
I animate a shot with a hard jumpy cut in the middle. first closeup then full body. the cut is in the "fast" part of the movement. a "real" linear key would allow me to control the last and first frame visible in each part of the shot. or simpler: how the cut works. I can also do this with another key later and just approximating the "fast" position. but it would be harder to control the cut. for this situation the workaround proposed by slowtiger would actually work very well. Of course even better would be a "real" linear key where one could just define one pose and have the movement come in fast. That way i can roughly approximate what i want and then when it feels right go into it with bezier.

Thanks to everyone for engaging and contributing!