What the hell is going on in this armature? The mystery of the ghost IK

I downloaded this https://www.blendswap.com/blend/2584

and started to play around with it, but quickly I noticed there were these orange dotted lines that never appear in any files. Seemed like the indicated the IK relation. The problem is, for most bones, there is no IK relation! Somehow the file is able to pretend there’s an IK relation between bones when there’s no modifiers for it, like the head! It’s a haunted file!

On top of that there is some other weird unknown relation with it’s ankle IK where when I try and move them at the same time as the hips they make the armature spin an extra amount. Normally this would be an indication of some kind of rotation limit, but there aren’t any!

The shrinkwrap modifier doesn’t seem to work on these mystery IK bones either. They should have the freedom to deform, and even though the shrinkwrap modifier is checked, literally nothing happens with any of the settings.

On top of that, the bones won’t record keyframe animations!

Seriously, what kind of crap is this? Who would release this catastrophe to the public?

Check your versions. Are you using the same one that the blend was created in?

It’s for Blender 2.5x… a wonder it’s opening at all in 2.81. Tried setting down some keyframes, it seems to work as expected (except the model itself is animated and it’ll get wonky because the armature doesn’t follow).
There are some objects set as “in front” and a displace modifier that wobbles the entire model, which I’m not sure is a good idea to keep.

I am not seeing these dotted lines but they can mean any relationship (parent or constraint), not necessarily IK.

What could possibly be the point of updating blender if you always have to revert to older versions? No, I’ve opened plenty of other blend files in later versions, this one has bad settings.

Exactly for that : compatibility. As things change over time, some functionalities are getting phazed out, others appear, and old files don’t work exactly like they should. That being said, this file has a lot of, uh… “caveats”.

Is that a joke or something? I looked it up. Blender 2.5 came out in 2009:
https://www.geeks3d.com/20090806/blender-2-5-release-date-announced/

I don’t think it’s reasonable to expect blender to be capable of opening files from that long ago correctly.

You don’t need to uninstall the current version of blender to use an old version of blender with old files. By default blender is built to be portable. Just download the zip version and add a folder named “config” under the folder that is named after the version number (in this case it would be 2.50) in the files you extract from the zip . That will tell blender to save all the configuration files to that folder and make it 100% portable.

It’s completely reasonable. If you couldn’t, then artists on a regular basis wouldn’t be able to open their old saves and build off of their work, they’d have to always finish everything on the fly. I already have multiple versions of blender, adding yet another one is just a waste of time, BF should be able to handle updates.

There is usually a reason behind stuff like this not being compatible. Lets take the old blender internal render as an example. They said that the code base was a mess (dating back to the mid 90s) and it was actually a lot more work than normal keeping it functional and too hard to extend. This was the motivation they had for removing it for 2.8 and replacing it with eevee.

Because of that choice materials set up in the old blender internal cannot work in versions after 2.79. Even making a portable version of blender internal was seen as too hard because the code for it relied on a lot of areas of blender that were being changed.

Well anyway, with its removal a lot of people were upset at having to convert the materials for old blends to cycles so they could use it with eevee. Maintaining compatibility with this engine was simply impossible without including the engine because it wasn’t a physically based render engine, but they change literally had to be made in order to move forward with a better performing and easier to develop for solution.

I don’t know what change they made to the animation system between 2.5 and now, but it was possible a similar situation. They simply can’t always add new stuff without trimming older code or changing how some things works.

IMO, the best thing to do is to simply stick with one version of blender for a project, and only upgrade when that is finished. You can always use a portable version of blender for any older projects that don’t work in the latest version.

If that’s the case then you’re saying blendswap is useless because it’s only the meshes and textures that matter, which many many many many many many many many other websites have an abundance of.

When I said “BF should be able to handle updates,” I meant they already do. As I said, nearly every old file I open works well. This file doesn’t even have an animation, just a pose library and some actions. As such, I would expect a few settings got ported over. It turns out there is actually a setting for armatures to show or not show dotted lines, something I didn’t know but clearly something BF thought about.

However, the pose interaction from what I see has some weird kinks to it that I haven’t ever seen in any other old file, so it’s likely the settings that are off and it wasn’t animated properly. If you don’t want to look through those settings to figure out how to make improvements, no one’s forcing you to. I myself had luck unparenting the ankles and keyframing the spine and hips whenever the ghost IK in the head moved and overwrote the previous keyframes.