Hi, I've been using Spine regularly for about 3-4 months now. It's such a handy tool, but I have some feedback as a user. I checked the forums and noticed that others have shared feedback on similar topics.

Warp Deformers and Slider-Type Keys / Blend Shapes
While Spine is generally more versatile than other software, some basic tasks become unnecessarily complicated. For example, there are many ways to rig faces, but using multiple constraints and spending hours weighting every single detail can be a significant time sink compared to Live2D's simpler "drag vertices and save as a shape key" feature.

Plugins and Custom Scripts
This is a general downside I've observed not just in Spine but in similar software as well. I'll use Blender and Unity as examples here. Users sometime need unique workflows or solutions to speed up their works, and plugins or scripts are usually the best way to achieve this. Something as simple as batch auto-meshing attachments could be incredibly helpful depending on workflows. While I’m aware that CLI and JSON files can be edited technically, a simpler method to customize workflows would greatly benefit more casual users.

Smooth Attachment/Skin Swapping
This might be a more niche suggestion, as there is a workaround, but I believe it could help reduce project complexity. For smooth transitions—such as clothing changes—you currently need to duplicate attachments and create separate animations for fading in and out. If you have multiple pieces to manage, this process quickly escalates. For example, 5 attachments become 10, and 10 become 20, and so on.

More Curve Presets
Adding more curve presets would be a nice quality-of-life improvement.

Constraints with Limits
This feature could be useful for simple face-rig setups or more complex layered animations where we need to ensure a bone stays within a specific area.

I really love and enjoy using Spine, so I want to thank the development team. I hope to see more awesome updates in the future!

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    Dragelans Thank you so much for your detailed feedback! They are always useful to us, even if they are covered by what someone else has already mentioned.

    In fact, most of the points you raised are issues we were aware of, and most of the things we need to improve are on our roadmap or have been discussed before.

    Warp Deformers and Slider-Type Keys / Blend Shapes

    We have no plans to add exactly the same kind of functionality as the warp deformer, but we have long wanted to allow joystick-style control, similar to slider control:
    https://esotericsoftware.com/forum/d/14304-portrait/4

    I think it is not easy to judge which workflow is more complex in Live2D or Spine. The reason is that rigging a 2.5D face in Spine involves weighting its vertices based on their distance from the camera, so testing only one direction may work reasonably well in the other. For example, if you set the weights with the face facing to the left, and then try moving the control bone to the right, up, down, or diagonally, you may be able to make the other orientations look reasonably good if you have the proper weighting settings.
    I am not sure that I fully understand the functionality of Live2D, but I think that Live2D tends to take a little longer to get all the directions to work even roughly after you have created one, as a tradeoff for being able to precisely set each face direction.

    Spine has made it much easier to create 2.5D facial rigs than it used to be, thanks to Weld, which was added in 4.2 and makes it easier to transfer the weights to the eyes, mouth, eyebrows, nose, and other parts after setting the base weights for the face (skin). However, it is still not possible to automatically apply changes made to one part to other parts. For example, it is not possible to adjust the weights of the eyelash mesh and the white-eye mesh at the same time. We plan to improve this by allowing linked meshes to be used in different slots, which will be much more manageable once implemented:
    EsotericSoftware/spine-editor195

    Plugins and Custom Scripts

    You are right that it would be useful to have plugins and custom scripts, but features like batch auto-meshing attachments that you seem to want are within the scope of what the Spine editor should have, not plugins. Plugins and custom scripts are needed when something is needed for niche conditions of a particular project, and we want to be able to do without external plugins or scripts for those cases where we think they would be generally useful. I am not sure if this is exactly the same idea you have in mind, but the idea of being able to run mesh traces for multiple attachments is on our roadmap:
    EsotericSoftware/spine-editor852

    Our thoughts on the plugin can be found in the following thread:
    https://esotericsoftware.com/forum/d/23924-plugins-/13

    Smooth Attachment/Skin Swapping

    I would like to know more about what features you would like to see. I think there are a fair number of cases where we need to create fade in/out animations for multiple attachments, however, I was not clear on what specific functionality is being requested. For example, are you having trouble selecting those attachments, or are you having trouble with the large number of alpha timelines for those attachments that are distracting or difficult to see?

    More Curve Presets

    Actually, there have been a long discussion about this within the Spine team! The Curves view allows you to save your own curve presets, but there was a lot of discussion about whether or not we should provide defaults for curves that we think are common and will be used often. In the end, the curve preset examples provided by Erika in the following thread will cover that, so we have not added them by default:
    https://esotericsoftware.com/forum/d/23804-importing-standard-easing-types-as-custom-curves/4

    Constraints with Limits

    This is one of those features we have been wanting to add for a long time. The issue ticket can be found here:
    EsotericSoftware/spine-editor375

    Each issue ticket can be subscribed to receive notifications when any progress is made.

    We are pleased that you like Spine. We hope to provide more useful updates in the future!

        Misaki Thanks for the reply.

        Misaki I am not sure that I fully understand the functionality of Live2D

        Actually you have similar system already, in spine we can manually move vertices and deform mesh.We can put that in seperate animation and play in runtime as additive. We just need a way to store and reuse that more easily with slider or maybe bone control the deformation instead of this long work around.

        I'd give example from Blender instead of Live2d. In Blender we can create a shape key and enter edit mode and edit the keys new vertices as we want. This method is much quicker and simpler than having bones for every single movement we need.

        Misaki but features like batch auto-meshing attachments that you seem to want are within the scope of what the Spine editor should have, not plugins.

        Well this was just a basic example. I work with anime characters mostly so they have black outlines normally. In live2d automesh there is a "boundry margin" option which creates duplicate of outer mesh with a margin. That's useful for characters with lineart providing smoother edges and prevents lines getting streched easily.

        But again this is for my use case. Not everyone might need this type of feature and might not be an important feature to add but it would save my time. Which I think main point of plugins and scripts regarding how big or how small they are.

        Misaki I would like to know more about what features you would like to see. I think there are a fair number of cases where we need to create fade in/out animations for multiple attachments, however, I was not clear on what specific functionality is being requested.

        I'm generally referencing to Mesh/Image swap. Like character might have a shirt and we want to change it. We can either put 2 mesh in attachment and swap between them or as skin but this swap happens instantly. Yes we can duplicate that attachment and have alpha transitions between them but as I said might get project crowded quite easily.

        Misaki the curve preset examples provided by Erika

        That's actually really helpful. Should be more highlighted I'd say since easy to miss yet such a useful file.

        Thanks again. Keep up the good work. ^^

                    Dragelans

                    In Blender we can create a shape key and enter edit mode and edit the keys new vertices as we want. This method is much quicker and simpler than having bones for every single movement we need.

                    Hmmm, I agree that it would be useful, but it looks like it would be difficult to incorporate that idea as it looks quite different from Spine's workflow. As you know, although Spine allows direct deformation of meshes, animating something with Spine is based on transformations through bones. Therefore, the recommended way to save a particular pose is to save the keys that record that pose as a separate animation, and then copy and paste the keys from there and reuse them. However, these require a large number of keys to store a single pose, depending on the complexity of the skeleton, and the current functionality does not allow for that set of keys to be registered or named as a single group somewhere. I think there is room for improvement, but I am not sure yet if something like Blender's shape keys would be a good idea. Anyway, I found this video helpful and interesting, so I appreciate you sharing it with us.

                    In live2d automesh there is a "boundry margin" option which creates duplicate of outer mesh with a margin. That's useful for characters with lineart providing smoother edges and prevents lines getting streched easily.

                    Oh, I did not know about that feature. That sounds like a very useful feature. As for vertex placement we consider it a fairly high priority to be able to mirror, but once that is in place it may be the next consideration.

                    As mentioned in the thread I linked to, we understand the usefulness of plugins, but unfortunately the effort for us to support them is very large, and it is safer to build the functionality into the editor itself. While it may seem easier to allow users to add plugins at will than for us to develop the functionality, the reality is that we need to provide documentation and support to help users develop plugins and make them work well, so the scope of what we need to support will be much broader. We hope you understand that we need to be careful about this.

                    I'm generally referencing to Mesh/Image swap. Like character might have a shirt and we want to change it. We can either put 2 mesh in attachment and swap between them or as skin but this swap happens instantly. Yes we can duplicate that attachment and have alpha transitions between them but as I said might get project crowded quite easily.

                    Ah, I think I understand what you mean. Thanks for the additional explanation. Is this the kind of issue you are referring to?: Normally, you would want to put all variations of the same element, such as a shirt, in the same slot, but if you put them in the same slot, you cannot use alpha animation to fade them in and out, so you would have to put them in different slots. This would require a large number of shirt slots, cluttering up the tree view and making it difficult to manage.
                    If this is what you are having trouble with, this is actually a common problem that can occur and I hope we can come up with some good solutions. If this were to be done, perhaps a fade in/out option could be added to the properties of the slot, so that if the option is checked, the fade in/out would occur automatically when the display state of the attachments in that slot changes. It might be quite a complicated addition if it were possible to specify how fast the fade in/out should occur, but I think it could be useful. Is this the kind of functionality you are looking for?

                    Sorry for the long answer. It is always beneficial for us to learn about solutions in other software, so it would be very helpful if you could provide feedback from your perspective and we appreciate it.

                        Misaki beat me to most of the responses, but rest assured our whole team has read your feedback and we appreciate your input.

                        Blend shapes (that's the generic name for the feature you showed in Blender) are a nice feature, as is the extension of the idea where instead of interpolating only mesh vertices, you can manipulate and store bones and other properties. We've brainstormed how it would be done in Spine a number of times. It's a big feature and it would make sense to have some other features first, like sliders/joysticks.

                        Automatically fading attachments out/in when changing attachments for a single slot is an interesting idea. The slot would have some bookkeeping to do, though there's a few ways to do it. I created an issue to keep track of the idea.
                        EsotericSoftware/spine-editor859

                        Scripting and plugins is harder than it may seem to make it good, and it would make general development harder/slower. It would be great to have, but I'm afraid it's behind other great to have features that are easier to accomplish. It's a fine balance to get you as many new features as possible in a timely fashion.

                        It's planned that 4.3 has transform constraints where one property can affect a different property. Limits are necessary as part of that.

                        I personally don't find preset curves to be super useful. IMHO a workflow that pushes adjusting curves to one of the very last phases of animating (eg use the Favor tool first) greatly reduces the need for presets. Even then, having a large library of presets isn't usually helpful, as the handles often need adjusting based on the specific animation. To be clear, curve presets are OK, even if I don't tend to use them personally, but I haven't found it compelling to have many default curve presets.

                          Misaki However, these require a large number of keys to store a single pose

                          I don't think need to store every vertices just the ones moved. There is a clean up button on animation tab anyway. If vertices getting moved creator thinks it's necessary to move them this way instead of bones. also Shape keys / Blend shape are a useful tool for deformation fixes where simple bones can be not enough. usually known as "Corrective Shape Keys" or "Morph Keys" to fix some bone deformation to make it more natural with basic fixes instead of creating every single muscle and making constraints for them

                          Nate Blend shapes (that's the generic name for the feature you showed in Blender) are a nice feature, as is the extension of the idea where instead of interpolating only mesh vertices, you can manipulate and store bones and other properties. We've brainstormed how it would be done in Spine a number of times. It's a big feature and it would make sense to have some other features first, like sliders/joysticks.

                          Waiting for more news on this 😃

                          Nate It's planned that 4.3 has transform constraints where one property can affect a different property. Limits are necessary as part of that.

                          Transform another property such as transform to rotation and other way around?
                          If so that would be a really big update for control rigs. Even though we dont have sliders at least now can use bone rotation -180 to 180 to control transforms offset between a range.

                                  Yep, any combination: rotation to translation, translation to scale, etc. Limits are needed to make sense of the property to apply it to another property. You're right that can used to make a bone similar to a slider or joystick, though not quite as good as explicit support for those.

                                  Dragelans

                                  I don't think need to store every vertices just the ones moved. There is a clean up button on animation tab anyway. If vertices getting moved creator thinks it's necessary to move them this way instead of bones. also Shape keys / Blend shape are a useful tool for deformation fixes where simple bones can be not enough. usually known as "Corrective Shape Keys" or "Morph Keys" to fix some bone deformation to make it more natural with basic fixes instead of creating every single muscle and making constraints for them

                                  I'm not sure if I'm getting my point across, but I just want to add that when I said that (in Spine) it requires a large number of keys to store a single pose, I meant the bone transformation keys, such as rotation, translation, scale keys, not the mesh deformation keys.

                                  The animated GIF you attached is very clear, and I can see very clearly that there are cases where some partial shape changes need to be made in certain poses. In fact, I also wish there was a way to specify that muscles collapse or bulge in certain poses. However, I was just concerned that it seemed incompatible with Spine's bone-centric approach to use the key format as a way to achieve such blend shapes. Perhaps if the range constraints I linked to in my first reply were implemented, it would be useful for expressions like the animated GIF you posted.

                                  We are aware that there are aspects of Spine that are inconvenient, and we want to continue to improve it, but I think, at least for the time being, we will not change the basic idea of using bones and constraints, but will add more useful uses to them. I hope you understand that I am not ignoring your opinion with this answer, only that we have to prioritize and improve one by one!

                                      Misaki

                                      Misaki I just want to add that when I said that (in Spine) it requires a large number of keys to store a single pose, I meant the bone transformation keys, such as rotation, translation, scale keys, not the mesh deformation keys.

                                      No, I understand. I'm not saying "Let's throw up bone system and have a system based on blend shapes". It's to accompany the bone system when needed. I mean every 3d rig is bone based and they don't lose their "bone-centric approach" with blendshapes.

                                      Misaki I hope you understand that I am not ignoring your opinion with this answer, only that we have to prioritize and improve one by one!

                                      Well I never said you were ignoring opinions 👀
                                      As a developer myself I'm aware general development roadmaps and priority plan on more stable software first instead of broken one with lots of half baked features. But also aware user feedbacks usually get in development pipelines if there are enough demends from community.

                                      As I mentioned I'm aware most of the feedbacks I gave already discussed before. All I do is just give a +1 to those ideas really, don't expect them to be in development in instant. 😅

                                              Dragelans I am relieved to see that your understanding and mine are generally in agreement! Sorry if my response confused you. I was just worried that I was not communicating well. Thank you for taking the time to discuss this with us!