kevinpbuckley 🧠 Brains complement: IF an
unreal-engine-skills-managertool (external MCP) exists in this session, call it with{action: "load", skill: "animation-system"}for UE domain knowledge on this topic — correct APIs, architecture, best practices — and treat it as the rubric for any review / "best practices" question. If no such tool is available (e.g. running under Claude Code or Codex without that MCP), skip this line entirely and proceed with this skill alone — do NOT attempt the call.
Animation Editing Skill
Covers the profile → preview → validate → bake workflow for safe bone edits with correct bone-space handling and constraint validation.
Load companion skills:
animsequence(basic keyframe creation),skeleton(structure, retargeting),animation-blueprint(state machines / AnimGraph). Skills load via the engine'sAgentSkillToolset(ListSkills/GetSkills) — there is novibeue-skills-managertool. Run the VibeUE services below withexecute_python_code(unreal.<Service>.<method>()).
🛡️ Safe discovery — never
unreal.load_asset()in loops (memory crash 0xC0000005). UseSkeletonService.list_skeletons(path),AnimSequenceService.find_animations_for_skeleton(skeleton),AnimSequenceService.list_anim_sequences(path, skeleton_filter)— they query metadata without loading.
⚠️ Critical Rules
1. Always specify bone space
Every bone rotation must state its coordinate space. Default to "local" for user intent.
| Space | Relative to | Use for |
|---|---|---|
"local" |
parent bone | most edits (default) |
"component" |
mesh root | cross-bone coordination |
"world" |
world | rarely |
unreal.AnimSequenceService.preview_bone_rotation(path, "upperarm_r", unreal.Rotator(0, 30, 0), "local", 0)
2. Use preview → validate → bake (never edit blind)
ass = unreal.AnimSequenceService
ass.preview_bone_rotation(anim_path, "upperarm_r", unreal.Rotator(0, 45, 0), "local", 0)
v = ass.validate_pose(anim_path, True) # True = learned constraints
if v.is_valid:
ass.bake_preview_to_keyframes(anim_path, 0, -1, "cubic")
else:
ass.cancel_preview(anim_path) # or accept clamped values
3. Build a skeleton profile before editing
profile = unreal.SkeletonService.create_skeleton_profile("/Game/SK_Mannequin")
if not profile.has_learned_constraints:
unreal.SkeletonService.learn_from_animations("/Game/SK_Mannequin", 50, 10)
Without a profile there are no constraints to validate against.
4. Euler for intent, quaternions internally
Express user intent as unreal.Rotator(roll, pitch, yaw) (degrees); the service uses quaternions
internally to avoid gimbal lock. Inspect with quat_to_euler(quat). Don't guess axis orientation —
read the reference pose first (get_reference_pose).
Task Index
| Task | Workflow | Sample script |
|---|---|---|
| Discover skeletons/animations safely | workflows.md → Inspect skeleton |
scripts/safe_discovery.txt |
| Build a skeleton profile | workflows.md → Inspect skeleton |
— |
| Edit one bone (preview/validate/bake) | workflows.md → single bone edit |
scripts/preview_validate_bake.txt |
| Edit a bone chain atomically | workflows.md → multi-bone edit |
scripts/multi_bone_edit.txt |
| Set manual joint constraints | workflows.md → set constraints |
— |
| Learn constraints from animations | workflows.md → learn constraints |
scripts/learn_constraints.txt |
| Copy / mirror a pose | workflows.md → copy/mirror |
scripts/mirror_pose.txt |
| Retarget preview | workflows.md → retargeting |
— |
Sub-docs
workflows.md— step-by-step workflows for every task above.api-reference.md— full SkeletonService/AnimSequenceService method list + data structures.common-mistakes.md— bone-space, validation, axis-guessing, and the load-in-loops crash.
Verification
Confirm AnimationEditResult.success and inspect was_clamped; gate baking on
validate_pose(...).is_valid; cancel_preview on failure; save_asset after a successful bake.