Foot sliding happens when a foot that should appear planted moves across the ground. In an In-Place game animation, the cause is usually not one bad key. Sliding is a mismatch between the pose, the implied travel distance of the animation, the speed used by gameplay, the blend, or the contact correction applied at runtime.
The fastest fix is to identify which layer introduces the mismatch. Do not start by adding IK to everything. A foot cannot remain naturally planted if the character capsule moves at a speed that contradicts the animation.
Understand the speed relationship
A locomotion cycle implies a travel speed even when its root is stationary. You can estimate that speed from the original Root Motion version or from stride length and cycle duration.
The basic relationship is:
Implied speed = distance covered by the original motion divided by cycle duration.
If a walk originally covers 150 centimeters in one second, playing the In-Place cycle while the Character Movement Component moves at 300 centimeters per second will usually create visible sliding. The character travels twice as far through the world as the feet imply.
Step 1: isolate the source of the slide
Test the sequence in several contexts:
- Animation Sequence preview with no blending.
- Target Skeletal Mesh after retargeting.
- Animation Blueprint at a fixed play rate.
- Gameplay with a fixed movement speed.
- Gameplay during acceleration, braking, and turns.
If the foot drifts in the raw sequence, the source or In-Place conversion needs work. If it appears stable until retargeting, inspect proportions, pelvis, and IK. If it appears stable until gameplay, the controller speed, play rate, blend, or state transition is the likely cause.
Step 2: verify the In-Place conversion
Removing forward translation from the root is only part of the conversion. The remaining body motion must still make sense around a stable origin.
- Remove or neutralize only the displacement that gameplay will provide.
- Preserve intentional vertical motion unless the project explicitly needs it removed.
- Check whether root rotation should remain, be removed, or be driven by gameplay.
- Inspect the pelvis for compensation that creates backward or forward drift.
- Review every contact phase after conversion.
For turns and attacks, a simple zeroed root can be especially misleading. The feet were recorded for an authored translation or rotation. If gameplay supplies a different curve, the contacts need to be reworked or the Root Motion variant should be used.
Step 3: match movement speed
Set the character to a fixed test speed and play the animation at its intended rate. Compare the feet during the planted phase.
There are three main ways to align the result:
- Change gameplay speed to match the clip.
- Change animation play rate within a reasonable range.
- Use a Blend Space or distance-based system with samples that cover the needed speeds.
Changing play rate is useful for small differences. Large changes alter weight, cadence, impact timing, and character personality. A walk played too fast can match velocity numerically and still look like a hurried or weightless performance.
Step 4: check the blend, not only the clips
Two clean animations can slide while blending because their feet contact the ground at different times or their implied speeds differ. Inspect:
- Idle-to-walk and walk-to-idle transitions.
- Walk-to-run blending.
- Forward-to-strafe and directional blends.
- Turn-in-place transitions.
- Inertial or long crossfades that mix incompatible contact phases.
Sync markers and well-planned transition rules can align recurring gait phases. Starts and stops often need dedicated animations rather than a long blend between a static idle and the middle of a locomotion cycle.
Step 5: retarget with contact awareness
A target character with longer or shorter legs changes stride and pelvis height. Even when the source cycle is clean, proportional retargeting can create drift or floating.
Review the target retarget pose, pelvis translation, leg chains, and IK goals. Test the target at the same world speed as the source. If the target needs a different speed range, adjust the locomotion system deliberately rather than expecting one retarget setting to solve every gait.
See How to Retarget Mocap Animations in UE5 for the complete setup.
Step 6: use foot IK for terrain and residual error
Foot IK is valuable for placing feet on uneven ground and reducing small contact errors. A typical runtime system traces the ground, offsets each foot, adjusts pelvis height, and blends corrections according to contact state.
Foot IK should not fight a major speed mismatch. If the capsule moves too far while the solver pins the foot, the leg stretches, the pelvis jerks, or the foot snaps when the pin releases.
Use IK after the underlying motion is close:
- Drive foot-lock strength from curves or reliable contact detection.
- Blend the lock in and out around the planted phase.
- Limit extreme offsets and leg extension.
- Adjust the pelvis smoothly so both legs remain plausible.
- Test steps, ramps, moving platforms, and network correction.
Step 7: handle acceleration and braking
A perfect fixed-speed loop can still slide when the character accelerates. The movement component changes velocity while the animation may still be playing a slow gait. Solutions include:
- Dedicated start and stop animations.
- Play-rate adjustment tied to measured speed.
- Blend Spaces with samples for several speeds.
- Stride warping or motion-matching systems where appropriate.
- Shorter, better-timed state transitions.
Choose the simplest system that covers the actual game. Advanced warping cannot replace clean source motion and sensible speed ranges.
Turn-in-place sliding
For an In-Place turn, compare the actor rotation curve with the foot contacts. If code rotates the capsule uniformly while the performance rotates in bursts around planted feet, the mesh will appear to skate.
Options include preserving authored root rotation, driving capsule rotation from an animation curve, using a dedicated turn system that advances rotation during the correct phase, or editing the turn to fit the controller. This is one reason Root Motion and In-Place versions are not always visually identical.
Common fixes that make the problem worse
- Pinning both feet at full strength. The body cannot progress naturally through the gait.
- Increasing play rate too far. Numeric speed matches but the performance loses weight.
- Removing every root axis. Intentional vertical motion and rotation may disappear.
- Using a long blend to hide a bad transition. Two incompatible contact phases remain mixed for longer.
- Testing only on flat ground. Pelvis correction and IK limits fail on real level geometry.
Diagnostic checklist
- Does the raw source have a stable planted phase?
- Was In-Place displacement removed without damaging pelvis motion?
- Does gameplay speed match the implied clip speed?
- Is play rate within a believable range?
- Do blends align compatible gait phases?
- Did retargeting change leg length, pelvis height, or contact reach?
- Does foot IK correct small residual errors instead of fighting large ones?
- Are starts, stops, acceleration, braking, and turns tested separately?
The choice between displacement models is explained in Root Motion vs In-Place Animations for UE5. When browsing mocap animation packs, check whether movement assets include Root Motion, In-Place, or both.