Child bones doesn’t follow parent when IK chain length are overlapping #73262

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Novice · 2020-01-20T13:02:47+01:00

Novice commented

2020-01-20 13:02:47 +01:00

System Information
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: Intel(R) UHD Graphics 620 Intel 4.5.0 - Build 25.20.100.6472

Blender Version
Broken: version: 2.81 (sub 16), branch: master, commit date: 2019-11-20 14:27, hash: 26bd5ebd42
Worked: 2.79

Short description of error
When a IK constraint passes another IK the armature get detached bones.

Exact steps for others to reproduce the error
Open blender with the default scene and remove everything.
Add armature. Tab into edit mode. Extrude a new bone. Extrude one more bone. They will all be connected to their parent.

Add a cube at the tip of the last bone and another one at the tip of the middle bone.

Tab into pose mode. Select the last bone (Bone.002). Select "Bone Constraint Properties" -> "Add Bone Constraint" -> "Inverse Kinematics". Select as target the cube at the tip of that bone. (In the blend file it's thumbIK). Change "Chain Lenght" to 2.

Still in pose mode select the middle bone, (Bone.001). Select "Bone Constraint Properties" -> "Add Bone Constraint" -> "Inverse Kinematics". Select as target the cube at the tip of that bone. (In the blend file it's wristIK). Change "Chain Lenght" to 2.

Go into object mode. Select the IK for the middle bone. Move it around and see how the last bone stays where it is. It doesn't follow the armature. This will cause models being deformed.

armature_detached_IK_2_79b.blend

Notice in the blend file how all bones are connected, except the first being created which doesn't have a parent.

Notice "Automatic IK" is not being selected.

**System Information** Operating system: Windows-10-10.0.17763 64 Bits Graphics card: Intel(R) UHD Graphics 620 Intel 4.5.0 - Build 25.20.100.6472 **Blender Version** Broken: version: 2.81 (sub 16), branch: master, commit date: 2019-11-20 14:27, hash: `26bd5ebd42` Worked: 2.79 **Short description of error** When a IK constraint passes another IK the armature get detached bones. **Exact steps for others to reproduce the error** Open blender with the default scene and remove everything. Add armature. Tab into edit mode. Extrude a new bone. Extrude one more bone. They will all be connected to their parent. Add a cube at the tip of the last bone and another one at the tip of the middle bone. Tab into pose mode. Select the last bone (Bone.002). Select "Bone Constraint Properties" -> "Add Bone Constraint" -> "Inverse Kinematics". Select as target the cube at the tip of that bone. (In the blend file it's thumbIK). Change "Chain Lenght" to 2. ![armature_thumbIK_chain_lenght_2.JPG](https://archive.blender.org/developer/F8289567/armature_thumbIK_chain_lenght_2.JPG) Still in pose mode select the middle bone, (Bone.001). Select "Bone Constraint Properties" -> "Add Bone Constraint" -> "Inverse Kinematics". Select as target the cube at the tip of that bone. (In the blend file it's wristIK). Change "Chain Lenght" to 2. ![armature_wristIK_chain_lenght_2.JPG](https://archive.blender.org/developer/F8289571/armature_wristIK_chain_lenght_2.JPG) Go into object mode. Select the IK for the middle bone. Move it around and see how the last bone stays where it is. It doesn't follow the armature. This will cause models being deformed. ![armature_detached.JPG](https://archive.blender.org/developer/F8289561/armature_detached.JPG) [armature_detached_IK_2_79b.blend](https://archive.blender.org/developer/F8299176/armature_detached_IK_2_79b.blend) Notice in the blend file how all bones are connected, except the first being created which doesn't have a parent. ![armature_connected_bones.JPG](https://archive.blender.org/developer/F8289556/armature_connected_bones.JPG) Notice "Automatic IK" is not being selected. ![armature_NO_auto_IK.JPG](https://archive.blender.org/developer/F8289558/armature_NO_auto_IK.JPG)

Novice commented

2020-01-20 13:02:47 +01:00

Added subscriber: @BlenderAmateur

Germano Cavalcante commented

2020-01-22 13:36:25 +01:00

Added subscribers: @dr.sybren, @mano-wii

Germano Cavalcante commented

2020-01-22 13:36:25 +01:00

I believe it is the same problem described in #73051
It worked on blender 2.79, but it doesn't work on 2.80.

@dr.sybren, can you confirm if it is the same problem?
To reproduce it, just open the attached file, move one target cube and then the other.

I believe it is the same problem described in #73051 It worked on blender 2.79, but it doesn't work on 2.80. @dr.sybren, can you confirm if it is the same problem? To reproduce it, just open the attached file, move one target cube and then the other.

Novice commented

2020-01-23 08:11:58 +01:00

It's a duplicate, I just attached a simpler blend file and showed the problem is still there with connected bones.

When I didn't see anything in the other report for a week after it was closed as invalid, but it was shown the problem was still there even with connected bones, I thought comments written after it was closed was not read. So I wrote a new bug report.

It's a duplicate, I just attached a simpler blend file and showed the problem is still there with connected bones. When I didn't see anything in the other report for a week after it was closed as invalid, but it was shown the problem was still there even with connected bones, I thought comments written after it was closed was not read. So I wrote a new bug report.

Sybren A. Stüvel commented

2020-01-24 10:53:38 +01:00

Closed as duplicate of #73051

Sybren A. Stüvel closed this issue

2020-01-24 10:53:38 +01:00

Sybren A. Stüvel commented

2020-01-24 10:54:23 +01:00

@BlenderAmateur Can you make the example file with Blender 2.79? As it was made with 2.80, I cannot open it in 2.79 to confirm that it's working there.

Germano Cavalcante commented

2020-01-24 12:27:53 +01:00

I updated the description with a file that opens in blender 2.79b

Sybren A. Stüvel commented

2020-01-30 10:31:53 +01:00

In #73262#857452, @mano-wii wrote:
I updated the description with a file that opens in blender 2.79b

♥

> In #73262#857452, @mano-wii wrote: > I updated the description with a file that opens in blender 2.79b ♥

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Child bones doesn’t follow parent when IK chain length are overlapping #73262