Repository: godot
Issue: Polygon2D does not deform it's mesh using the physics-interpolated position of Bone2Ds
Labels: bug,topic:physics,topic:animation,topic:2d

### Tested versions

`4.0.dev1`, `4.3.RC1`, `4.3.stable`, `4.4.dev6`, `4.4.dev7`


### System information

Godot v4.4.dev7 - Windows 10 (build 19045) - Multi-window, 1 monitor - Vulkan (Mobile) - integrated AMD Radeon(TM) 760M (Advanced Micro Devices, Inc.; 31.0.24018.2001) - AMD Ryzen 5 7640U w/ Radeon 760M Graphics (12 threads)

### Issue description

Polygon2Ds do not deform their mesh using the physics-interpolated position of Bone2Ds that are translated during a `_physics_process` step. 
This means that games running at a higher framerate than their `physics_ticks_per_second` value will result in choppy Polygon2D deform motion.

I believe that the Bone2Ds are interpolating correctly, and that the issue is somewhere with how or when the Polygon2D decides to acquire the Bone2D's position to calculate mesh deforms.

### Demo of the Issue

I have setup a scene with the following features:
- a Polygon2D (the big tree) with a simple bone structure. Each bone has a script attached that will modify the `position` of the bone by some amount in the `_physics_process()` function. 
- Two Sprite2Ds (the apples) with `Physics Interpolation` turned off attached as children to two of the tree's bones to demonstrate that the Bone2Ds are actually interpolating (as the motion of the apples would be choppy if the bones were not interpolating)
- The position of the bones are drawn every frame with yellow circles, again, to demonstrate that the bone2ds are interpolating.

With a `Physics Tick Per Second` of `60`, the motion of everything appears smooth, as the physics is updating faster than the drawn framerate:

https://github.com/user-attachments/assets/12f50128-598a-4041-a6b9-251c18f40f16


However, if we drop the `Physics Ticks Per Second` to anything below the framerate, in this case `5`, the deform of the Polygon2D appears choppy despite everything else in the scene moving smoothly due to physics interpolation.

https://github.com/user-attachments/assets/bfd3fc99-c585-4492-b549-431d0b84d291

There's a few things here to notice:
1. The Bone2Ds are only updating their position in-code at only 5 ticks per second, but because they are interpolated, the yellow circles that represent their position and their children (the apples) appear to move smoothly.
2. The Polygon2D (The tree)'s motion is choppy, moving only once per physics tick, which is running at 5 ticks per second. We would expect this motion to be smooth, as the mesh deform should update every time the bones move, including interpolated motion.

### Steps to reproduce

1. Create a Polygon2D, attach a texture.
2. Create a Skeleton2D with a bone hierarchy and rest pose.
4. Attach the Skeleton to the Polygon2D
5. UV map the Polygon2D, and assign weights to each vertex corresponding to a bone in the skeleton.
6. Write a script that moves one more more bones in the `_physics_process` function.
7. Enable physics interpolation in your project settings.
8. Drop the `physics ticks per second` to something below the framerate that the game will run at. I'd suggest something very low, like `5` to clearly demonstrate the issue.
9. Run the scene.
10. Notice that despite the Bone2Ds ostensibly interpolating, the Polygon2D will not deform using any interpolated position values.

### Minimal reproduction project (MRP)

https://github.com/CodeZombie/godot4_polygon2d_phys_interp_bug_repro