Nilufer Please don't hesitate to ask questions here! While there are various tutorials on 2.5D rigs, I completely understand that it can be difficult to actually try them out if they don't quite match your character's look.
This time, I'll focus solely on the torso setup again. I understand that what you ultimately want to create is an attack animation, but if you can first grasp how to set up the attachment switching parts, you should be able to apply that knowledge to all sections.
First, I want to emphasize again: what I'm explaining here is simply a more practical application of the techniques used in this mesh binding tutorial: https://esotericsoftware.com/blog/Mesh-binding-tutorial
The fundamentals are the same. The technique of binding a mesh to bones during animation is extremely useful for creating 2.5D expressions.
Below, I will explain how to set up the torso so it can turn from a diagonal front-facing orientation to a diagonal back-facing orientation:
The files for this example project are here:
This Spine project file contains three skeletons, named [Step1], [Step2], and [Step3].
Step 1. Setup with a diagonal front-facing orientation
[Step1] is set up so that you can change the torso's orientation by moving the front shoulder bone, just like with Spineboy:
Since this is the same setup explained earlier, I'll skip the detailed setup method. However, the key point when performing this kind of setup is to adjust the weights while moving the shoulder bone in Animate mode, targeting a frame where it faces directly sideways:
I tried to keep it as simple as possible, but unfortunately, ensuring the beauty of the result required setting a certain number of mesh vertices. I apologize if the setup above seems very complex to you.
I didn't start with a large number of vertices. Instead, I meticulously repeated the process of adjusting weights in Animate mode and then returning to Setup mode to adjust the mesh vertices whenever they seemed insufficient. You can technically edit mesh vertices in Animate mode, but I often find myself switching to Setup mode for adjustments because it's easy to accidentally distort the mesh or cause issues when editing vertices in a pose other than the bind pose.
While various tutorials mention the point of adjusting weights within Animate mode, I want to emphasize once again how critically important this step is. Especially when dealing with very large deformations like in this case, make sure to translate the bones first within Animate mode, and then proceed to adjust the weights.
Step 2. Bind the torso facing diagonally backward in Animate mode
From here on, we'll go through the procedures in more detail. You can verify the state after completing this step using the [Step2] skeleton.
I'm sorry the resolution is low because the size became too large and I had to reduce it. I'll show you the mesh editing process for reference, but you don't need to make it exactly the same:
Create an animation to save the bind pose, displaying the back-facing attachment and hiding the front-facing attachment within the animation:
Move the shoulder bones to align with the back-facing pose, then adjust the arm bones slightly as needed. Bind the Body, Shoulder-Front, and Shoulder-Back bones to the Body-Back mesh attachment:
At this stage, keep the mesh vertex settings rough and simply bind it for now.
Next, copy the key for the bind pose and switch the active animation to animation. Move the key that was originally at frame 20 backward, paste the bind pose key at frame 20, and switch attachments at frame 10. Once the Shoulder-Front bone is positioned directly beside the body, create an animation that switches the displayed attachment from facing forward to facing backward. Just a heads-up: it won't look very clean at this stage:
At this stage, it looks like this:
Step 3. Adjusting the mesh and weights of a torso facing diagonally backward
The body has collapsed, but since we've already completed the crucial technique of binding within animate mode, all that remains is the tedious task of adjusting the mesh vertices and weights.
I've uploaded a video of the process here for your reference if needed:
The key point is that mesh vertex additions should be done with the bind pose, while weight adjustments should be performed on the frame where the bone is positioned directly beside the body. By doing this, the mesh attachment will always display cleanly when the bone has exactly the same transform values as the bind pose. Therefore, by focusing on how closely the mesh matches the previous attachment at the moment of switching and adjusting the vertices and weights to maintain that visual continuity, you can achieve a smooth transition. This enables the body to seamlessly display an entirely different side, creating the impression of three dimensional movement.
I hope this explanation clears up your questions, but if anything remains unclear, please feel free to ask.
