rigify limbs.paw ik stretch does not fully disable stretch #104724

New Issue

Iliya Katushenock · 2023-06-29T17:57:15+02:00

Iliya Katushenock commented

2023-06-29 17:57:15 +02:00

System Information
Windows 11

Blender Version
3.6 LTS but affects previous versions as well

when using a limbs.paw rigify type (may affect other rig types as well) if you set IK not to stretch it still stretches a little, this is not obvious if all you are doing is using the rig in blender and has no impact but if you are baking the deform bones out for a game engine where stretching is not supported or you just don't want it (and even in blender when baked if you copy the deform bone transforms) you get jittering and movement in the toe and foot bones.

to reproduce.

enable rigify
create empty armature
samples add limbs.paw

generate rig

in pose mode click on foot_ik.L and in the item menu disable IK Stretch by setting to 0

create a simple animation that moves thigh_ik.L but leaves the foot in place

bake the animation using visual keying, Clear Constraints Pose and everything else unchecked

enable armature layer 29 so you can see the deform bones, play the animation you will see the toe and foot bones wiggle which is representative of what happens if you bake this out non destructively for game engine.

Workaround
repeat the above
set IK Stretch to 0 as before
open armature layer 30 to get to the MCH bones

select MCH-shin_ik.L and in bone constraints for both IK controllers uncheck Stretch

create simple animation as above and bake, note that toe and feet no longer move after baking.

Having a bit of a search around I think this is causing quite a few issues in various game engines, suspect this is root cause.

Obviously there are other causes like Unitys default animation optimisation that can also cause jitter if not set correctly but I think this is something causing some confusion around.

Originally posted by @MarkEdwards in /blender/blender/issues/109488#issue-99391

**System Information** Windows 11 **Blender Version** 3.6 LTS but affects previous versions as well when using a limbs.paw rigify type (may affect other rig types as well) if you set IK not to stretch it still stretches a little, this is not obvious if all you are doing is using the rig in blender and has no impact but if you are baking the deform bones out for a game engine where stretching is not supported or you just don't want it (and even in blender when baked if you copy the deform bone transforms) you get jittering and movement in the toe and foot bones. to reproduce. enable rigify create empty armature samples add limbs.paw generate rig in pose mode click on foot_ik.L and in the item menu disable IK Stretch by setting to 0 create a simple animation that moves thigh_ik.L but leaves the foot in place bake the animation using visual keying, Clear Constraints Pose and everything else unchecked enable armature layer 29 so you can see the deform bones, play the animation you will see the toe and foot bones wiggle which is representative of what happens if you bake this out non destructively for game engine. Workaround repeat the above set IK Stretch to 0 as before open armature layer 30 to get to the MCH bones select MCH-shin_ik.L and in bone constraints for both IK controllers uncheck Stretch create simple animation as above and bake, note that toe and feet no longer move after baking. Having a bit of a search around I think this is causing quite a few issues in various game engines, suspect this is root cause. Obviously there are other causes like Unitys default animation optimisation that can also cause jitter if not set correctly but I think this is something causing some confusion around. _Originally posted by @MarkEdwards in /blender/blender/issues/109488#issue-99391_

Iliya Katushenock referenced this issue from blender/blender

2023-06-29 17:58:07 +02:00

rigify limbs.paw ik stretch does not fully disable stretch #109488

Iliya Katushenock added the

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rigify limbs.paw ik stretch does not fully disable stretch #104724