IKControl's Offset Position no longer updates when Model:ScaleTo() is performed

Bug Reports Engine Bugs
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#1

If a model has an IKControl affecting any of its descendants, and the model’s scale is changed with Model:ScaleTo(), the IKControl’s offset position fails to update with the new size of the model. This did not used to happen until about a few weeks ago. IKControls used to update its offset position when the model changed sizes.

I am currently working around this by setting the parts of ChainRoot and EndEffector to nil for one frame, then back to the original parts.

Expected behavior

I expect the offset position of IKControls to update with the scale of the model if the model is scaled with Model:ScaleTo(), as it did previously before something was changed.

#2

Hi, we can’t seem to reproduce the issue. If the model has an IKControl under it, and :ScaleTo() is called on the model, the .Offset (and .EndEffectorOffset) property is scaled accordingly to the new factor.

Is the IKControl under the model you’re scaling? Could you provide more detailed reproduction steps or a placefile? Thank you

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#3

Hi there, just wanted to follow up again to see if you are able to provide further instructions to reproduce the issue. As mentioned above, a placefile or code snippet/screenshots of how you set up the IkControl would be helpful.

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#4

Thanks! I haven’t been able to create a reproduction file that isolates the issue, but here is how I have set up my IKControls:

  1. Create an IKControl with Type set to Rotation, and Pole set to nil. In my game, the EndEffector is set to the Head part of my custom character, and the ChainRoot is set to the base of the neck, which allows its head to turn based on the camera’s position with a script. Have the Offset Position set to 0,0,0.

  2. Have the IKControl set to Enabled = false while changing the scale of the model that holds the parts. This will not cause the bug to happen. However, if Enabled = true while changing the scale of the model, the parts’ offset positions will fail to update properly.

I first noticed this on February 7, but it could have started happening any time after December 27, which was the last time I tested it working correctly. I made no changes to my script of the IK properties.

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#5

Hi there, we have deployed a potential fix for this issue. Could you try scaling the model with IKControl again to see if you’re still seeing the issue on your end? Thank you.

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#6

Hello! I have tested it, and I am still having the same issue when I scale the model down, but it is no longer happening when I scale the model up.

Edit: Actually, upon further testing, it has the same behavior as before. The offset is failing to update when scaling both up and down.

#7

Thanks for confirming. Do you have screenshots of what you see before / after you scale the model down you can share here?

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#8

Hello! I tested it further, and it actually still has the same behavior as before. Scaling the model both up and down cause the IKControl’s offsets to be broken.

Scaling up: (It squishes the neck into itself)

Scaling down: (It elongates the neck parts)

I run this code every time the character changes the scale of its model as a temporary fix:

local ChainRoot = Character.HumanoidRootPart.IKControl.ChainRoot
local EndEffector = Character.HumanoidRootPart.IKControl.EndEffector
Character.HumanoidRootPart.IKControl.Enabled = false
Character.HumanoidRootPart.IKControl.ChainRoot = nil
Character.HumanoidRootPart.IKControl.EndEffector = nil
task.wait(0.1)
Character.HumanoidRootPart.IKControl.ChainRoot = ChainRoot
Character.HumanoidRootPart.IKControl.EndEffector = EndEffector

These are the results when the code is added. I am scaling the character down in the example.

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