Fix Skeleton3D falsely assuming all physical bones will be children of their first bone

[CheesecakeCG]

physical_bones_start_simulation_on was falsely assuming all physbones will be children of the first bone in their skeleton.

I've changed it so when the list of bones is empty, all physical bones start simulating, which more accurately reflects the documentation.

This issue might also affect 3.x, I vaguely remember running into something that might have been this.

[fire]

Are you able to describe what happens previous and with the fix so I can check it does what it says it does? Like a video or a description.

[CheesecakeCG]

Are you able to describe what happens previous and with the fix so I can check it does what it says it does? Like a video or a description.

Before, any PhysicalBone3D's that were assigned to bones that weren't parented to bone ID 0 got ignored by physical_bones_start_simulation() in GDScript. So in the case of this skeleton, it ignores all of the PhysicalBone3D's since none of them are parented to bone ID 0, "Root".

In this skeleton, all the bones are parented to "Hips" still, but since "Hips" now is now bone ID 0, the rag-doll sim starts like you'd expect.

The second one is an older version of the same rig in Blender, but the biggest relevant difference I that I did not enable "Export Deformation Bones Only" in the GLTF export on one character but not the other. However, these aren't off the shelf rigs, so I have no idea how many people actual run into this issue.

[fire]

@reduz @fabriceci can you check? Your explanation makes sense but I'm not that familiar.

[akien-mga]

@CheesecakeCG FYI, the Git author details you used to author this commit don't seem to match your GitHub account (see the "From:" line on https://patch-diff.githubusercontent.com/raw/godotengine/godot/pull/67282.patch), that's why the commit doesn't appear with your avatar. It's not a problem for Git but if you want to be credited as contributor if/when this is merged, you might want to change that (you can change your Git identity locally, then edit the commit with git commit --amend --reset-author and force push with git push --force to update the PR).

[CheesecakeCG]

FYI, the Git author details you used to author this commit don't seem to match your GitHub account

Thanks for letting me know! Should be fixed now.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉

[akien-mga]

Cherry-picked for 3.6.

[timothyqiu]

Cherry-picked for 3.5.2