How to fix and prevent this flexi-binding issue?

[mmmaarten]

Hi,

I'm working my way through the rigging in Moho Debut 13.5.5 now together with flexi-binding and it looks and feels great and very intuitive, but I now stumbled upon an issue that I don't know how to fix in Moho, at least not without disturbing my workflow too where I'd rather not go:

When rigging an elephants trunk by moving the last bone, one of the bones in the middle gets dragged with it, eventhough the visual strength region I set for the bone as far from it from both sides:

Issue:


Strength of bones:




original image connected to the trail of bones:


I am very familiar with doing meshes with Spine (also used some other software with meshes, but mainly Spine) and never had this issue, because in Spine we need to draw the mesh manually ourselves so we can create it exactly the way we like. We can let Spine calculate the weights per vertex after that, but we are also able to set the weight (comparable to strength in Moho) for each vertex per bone, so in great detail and with full manual control if we want. Because of this we can exactly tell which pixels to affect when rotating selected bones. So this issue is never an issue in Spine when setting up the mesh and weights the right way.

I'm sure the issue I'm facing now doesn't need to be an issue in Moho and it's just me getting to know the way to do this in Moho as it all looks and feels very thorough and cleverly figured out in the software. But I'm struggling on how to do this. I'm bound to Debut for now, so can't use smart bones. Also I don't like to draw images to have a straight trunk and then bend it in Moho. That might have a better result while bending, but I like this workflow better for just small movements and with Spine, where I used the exact same images before and finished this animation before, I didn't have to. So I'd rather not discuss about the workflow, but am hoping Moho Debut can do the same with the images I currently have.

So how to fix this stretching issue in Moho? Is there a way to add some border so Moho's flexi-binding system doesn't let bones affecting beyond that border, Like a seal? Or is there another way to have finer control over the underlying mesh and its vertices and weights? Or is there perhaps something I'm missing here or could be done to fix this with these exact images?

Thanks in advance!

BTW if you want to see the full image/animation I've created before in Spine and now try to recreate partly to learn Moho, it's here on YouTube:

[synthsin75]

On the bone layer settings, Bones tab, try Region binding. You may need to readjust your bone strengths after doing this, but region binding is meant to ONLY affect the art in the bone's strength region, where Flexible binding allows all bones to affect all the art, depending on their strength. With flexible binding, you'd need more bones to kind of frame-in and isolate an area from the influence of other bones.

[mmmaarten]

Thanks for the quick response! I didn't know there was even another method! Great! Sounds like the thing I'm after.

Trying it out now, but don't quite get why I'm getting these weird results tho; it looks like it's still moving more than the strength-area (or too little?). But if I make it too small it also doesn't work. Looks like with this method I need way more bones to adjust to the edges to get finer control, but I would think it should work with the regions I adjusted now to this method as all pixels fall within on the places the issues appear? Any tips?




[edit] The gap at the setup pose seems to be perfectly isolating both regions, but for some reason it's still stretching pixels that are within a region left when moving the last bone:

[Daxel]

As those two parts of the drawing are very close, the quickest fix I would try is to make that last horizontal bone of the trunk shorter. Ah no sorry, I see the trunk is getting distorted too, then it's not that easy.

The problem is that even if you are being carefull with the bone influence, it is not precise because if I'm not mistaken Moho internally uses a mesh system to determine which pixels will be affected by those bone influences, so it's not pixel accurate, as you can't see the real mesh that is being used internally.

My recomendation would be to use meshes to have more precision. They are incredibly convenient in Moho now, very easy to use with the latest improvements. You can still use the skeleton you have. If you only need precision on the trunk, I would create a mesh layer just for the trunk layer to use point binding there instead of flexibinding and I would leave the rest of the rig as it is.

Here you can see a quick example by Victor Paredes: https://www.youtube.com/watch?v=eHNvjlcR8tI

[synthsin75]

Part of the problem is that the bones are trying to stretch very close parts of the image. As a single image, it would be better if the trunk were drawn straight. There's really only two solutions for that particular image. Either break the trunk into multiple separate images, or use a smart warp vector mesh. Breaking up the image may not be desirable, as painted details can expose the breaks. A smart mesh is more involved (and not available in Debut), but coming from Spine, they'd probably be more intuitive for you.

If you cannot upgrade, I'd really suggest drawing the trunk straight, as the simplest solution.

[Daxel]

Oh yeah I didn't notice you were using debut. Then I would do what Wes said, or maybe try to cut just the tip of the trunk apart.

[synthsin75]

"Create smooth joint for bone pair" is not available in Debut either. I had to check, as I thought Victor's old trick of using multiple copies of the same image would work: viewtopic.php?f=9&t=27158

It's just much harder to do anything much beyond cutout animation in Debut...at least with images. If I only had Debut, I'd seriously consider tracing it in vectors.

[Greenlaw]

In this situation, I would straighten out the trunk and then rig and animate it using Sketch Bones. This is how I rig and animate anything that needs to be fully flexible, like tails, noodle arms, rope, whips, etc. This gives you the cleanest and most predictable deformations, and requires the least amount of work...at least for rigging and animation. (This would be true in pretty much any animation program, 2D or 3D, that uses bones for deformation.) That said, I'm not sure this tool is available in Debut. If Debut doesn't have the Sketch Bones tool, you'll need to create and animate the bones manually.

If you have the option, you should re-draw the trunk or otherwise straighten it out before rigging it. If you don't have a good way to do this in your paint program, you can use Moho to roughly straighten the image, render it, and then clean it up in the paint program and reimport it. In Debut, that means using bones to straighten the art; in Pro you would probably create a custom mesh to straighten the image because it's more precisely tweakable.

If you ever upgrade to Pro, another option you can look into is Selective Flexi-binding. If you chop up your artwork into multiple layers, you can use this to restrict the deformation of each layer to specific bones. (This used to be my primary rigging method.)

Smooth Joint was mentioned above but I don't think this is ideal for a flexible trunk; it works best for elbows and knees, when the deformation is fairly localized in a small circular region. My Puss rig for the interactive episode is a good example of Smooth Joints in action: My Puss-In-Boots Demo Reel. I also used this for Thighsander Plunderhorse's arms and legs in All Hail King Julien which you can see on my 2017 demo reel.

IMO, Debut is a fine tool for rigging and animating simple cut-out styles, and if you limit yourself to that you can do marvelous work with it quickly. But if you're trying to produce work in more advanced styles, you really should upgrade to Pro.

Hope this helps.

[mmmaarten]

Thanks a lot for your responses and thinking along guys. Unfortunately currently I have no way to upgrade to Pro. I'm hoping to be able to do that soon, but for now I need to learn Moho via Debut. BTW I bought Debut because I was hoping I could make any use out of it, but mainly to already learn something Moho to not waste time. But after diving in I won't use it for projects tho as it's basically realistically impossible. This task alone proves that. But hey, you won't hear me about that when I have pro

To walk through your suggestions:

DRAW THE TRUNK STRAIGHT
I understand that's the best way if I would like to have the best bending result. But for me that's not realistic as a workflow in this case. For one because I am animating sketches I made before and want them to be the same. I would choose this if it would be a flat style clean vector drawing, but with this raster painted style it's basically impossible or at least too time consuming to do. Still I would try it if this would a real world project and I needed to because I had no other software, but I could do the same in both Spine, OpenToonz and probably also Blender, so it wouldn't make sense to use Debut for this if I can't even render to 1920x1080 or more than 2 minutes of video.

BTW If I can avoid this method I would always do that, even when compromising a little on bending quality of a mesh, because than I can always see the end result while drawing in the drawing tool. And I don't like getting back and forth from Krita (or other tool) to Moho and back everytime just to see if bending already looks as wanted.

TRACING INTO VECTORS
I would choose vectors over raster when having equal fills like flat style any time. But not for this style. For this vectors just aren't realistic. Mostly because it's all painted in Krita by preference of these rasterbrushes (and great fun to paint in that software) and the last thing I want for this style is to loose that great painting feel of strokes and imperfections. But even if I would still try to trace it it wouldn't be possible to do that automatically with Debut, because Debut only traces 1 color (black). Perhaps I could try other software to do that, but as you and I know, there's no perfect tool for this. No tool could actually trace this exactly the same to vectors. Doing it manually would be a nightmare and way too much work to get it right.

And that would all be for just learning Moho... not even a real world project.

USE A SMART WARP LAYER (= MESH)
This sounds like a great alternative. If it would be possible in Debut tho.

Question about this tho:
I see Victor do this with a skeleton rig, but he's only using 1 image for the mesh AFAIK. Is it also possible to use a skeleton rig as I have now, so keep the bones AND keep them connected to individual images and decide to only replace one or more images (like the trunk) by warp layers to have those bones control the warp layer mesh instead and let the other bones still control the 'normal' images (or flexi stuff), while all parenting/fk/ik still works? So can we use these warp layers as children of a bones layer/hierarchy? (hope I explained this well)

BREAK THE WIDER END PART OF THE TRUNK INTO ITS OWN IMAGE
This would be the first thing I would go for when this would be a real world project. Great idea. I wouldn't split the full trunk as that would be impossible to get the same result I think. But only move the 'tip' to its own image sounds like a great plan and not that much of extra work.


CONCLUSION
Guess the result is that today I learned something new about the way Moho handles meshes in different ways. Even though it isn't very realistic to do these kind of things (or any real world things honestly) in Debut to do the right way obviously, but that I already knew...

Could some of you please answer the question about using Smart Warp layers inside existing skeletons with single images? (above)
Than I could add that to my workflow notes on how to do this so I already know all that and know the capabilities of Pro so I can directly work in pro when I got it later. That would be very appreciated!

Thanks again for your help. And have a great weekend!

[mmmaarten]

Hi Greenlaw,

Looks like our posts crossed each other.

> If you don't have a good way to do this in your paint program, you can use Moho to roughly straighten the image, render it, and then clean it up in the paint program and reimport it. In Debut, that means using bones to straighten the art

Huh? But isn't it the whole issue that Moho can't bend it without adding unwanted artifacts? That's the whole point. If it would work I wouldn't need to bend it right?

And if everything is so difficult to do in Moho Debut than I could easily switch to Spine and do it there without this issue. Or another tool, like OpenToonz or perhaps even Blender?

> IMO, Debut is a fine tool for rigging and animating simple cut-out styles, and if you limit yourself to that you can do marvelous work with it quickly.

I'm sorry to say, but I have to dissagree on this. It's pretty unrealistic to use for real world projects, even for simple cut out rigs or moving and rotating things around IMO. For one because you can't export more than 2 minutes, but mostly because you can't even export to 1920x1080. Which, honestly is just unbelievable to me for a payed product. Especially because OpenToonz is free, also has meshes and bones and way more and don't have all these waaaay too strict limitations. To me it's pretty clear that Lost Marble don't want us to use Debut, but straight buy Pro. Otherwise it would at least not limit AND basically all tools you need AND limit its export and import stuff to a point where basically nothing is left other than create an advanced thumbnail.

But you don't hear me about that anymore when having pro (and from what I've seen I already love that version)

Have nice weekend again!

[synthsin75]

Question about this tho:
I see Victor do this with a skeleton rig, but he's only using 1 image for the mesh AFAIK. Is it also possible to use a skeleton rig as I have now, so keep the bones AND keep them connected to individual images and decide to only replace one or more images (like the trunk) by warp layers to have those bones control the warp layer mesh instead and let the other bones still control the 'normal' images (or flexi stuff), while all parenting/fk/ik still works? So can we use these warp layers as children of a bones layer/hierarchy? (hope I explained this well)

Absolutely! You can freely mix art using flexibinding with art using a smart mesh, all in the same bone layer rig. The same bones that's you're trying to use for the trunk would just be controlling the smart mesh...which in turn warps the art much more predictably.

[synthsin75]

> IMO, Debut is a fine tool for rigging and animating simple cut-out styles, and if you limit yourself to that you can do marvelous work with it quickly.

I'm sorry to say, but I have to dissagree on this. It's pretty unrealistic to use for real world projects, even for simple cut out rigs or moving and rotating things around IMO. For one because you can't export more than 2 minutes, but mostly because you can't even export to 1920x1080. Which, honestly is just unbelievable to me for a payed product. Especially because OpenToonz is free, also has meshes and bones and way more and don't have all these waaaay too strict limitations. To me it's pretty clear that Lost Marble don't want us to use Debut, but straight buy Pro. Otherwise it would at least not limit AND basically all tools you need AND limit its export and import stuff to a point where basically nothing is left other than create an advanced thumbnail.

Let's face it. Debut is really meant to be the gateway to the Pro version. It's made for children and hobbyists, at best, and isn't designed for any professional quality work. But for the target market, a cheap option that allows people to do limited, cut-out animation quickly, it's not all bad. Animations primarily shared with friends, making gifs, etc. don't need broadcast quality...or episodic length. And really, export length isn't even a consideration, since there are plenty of free NLEs...and a single animation shot longer than 2 minutes is waaay too long.

Yes, there are free options, like OpenToonz, but often the learning curve or time-commitment for frame-by-frame is a barrier for Debut's target market.

But if you're looking to do professional work, you shouldn't expect to pay only $60 for software. Yes, there are free options, but in the paid market, that's a deal.

[mmmaarten]

Absolutely! You can freely mix art using flexibinding with art using a smart mesh, all in the same bone layer rig. The same bones that's you're trying to use for the trunk would just be controlling the smart mesh...which in turn warps the art much more predictably.

Thanks! That's great!

Let's face it. Debut is really meant to be the gateway to the Pro version.

Yes, that's exactly what I wrote: a paid trial version. So we agree.
I would be surprised to see kids nowadays pay 60 euros to design social media profile pictures or related tho. It's 2022. There's way too much free stuff and cheap apps out there.

But if you're looking to do professional work, you shouldn't expect to pay only $60 for software. Yes, there are free options, but in the paid market, that's a deal.

Sad to read you are twisting my words. I think I was pretty clear tho.

[synthsin75]

Let's face it. Debut is really meant to be the gateway to the Pro version.

Yes, that's exactly what I wrote: a paid trial version. So we agree.

No, both Debut and Pro have a free trial.

I would be surprised to see kids nowadays pay 60 euros to design social media profile pictures or related tho. It's 2022. There's way too much free stuff and cheap apps out there.

Well, that seems pretty unfair to characterize it as only able to make profile pictures. Debut is far more capable than a cheap app.

But if you're looking to do professional work, you shouldn't expect to pay only $60 for software. Yes, there are free options, but in the paid market, that's a deal.

Sad to read you are twisting my words. I think I was pretty clear tho.

Not trying to twist anything. Just saying that in the paid market $60 is cheap for the capabilities. I get that it's not for you. Debut doesn't offer enough for me either. But it does have a market at its price point.

[mmmaarten]

Well, that seems pretty unfair to characterize it as only able to make profile pictures. Debut is far more capable than a cheap app.

This was paraphrasing what you wrote yourself. This is not my opinion, I explained with content why I think that reasoning is off.

I don't like the direction this thread is going and how my professional content-based opinion is now downgraded by words that are taken out of context of mistaken. Like this it's not helping neither of us. I'm pretty sure you are a great guy, you also tried to help and thank you for that, and I totally get that you are defending the Moho you love. But understand we're on the same side here. I like Moho too and am already convinced about pro by everything I read and saw about it. Eventhough I don't have it yet. Also I did a dive into the trial of pro weeks before. I already wrote this in my previous posts.

I am straight and honest about Debut, but can't wait to get pro later and wrote that several times very clearly already. I won't bring this Debut-topic up again and won't respond to more about that and kindly ask you to do the same.