procedural-animation

Procedural Animation — Bones Driven by Code

Generated clips give you 80% of a character. The remaining 20% — the eye contact when an NPC speaks, feet that plant on slopes, hands that wrap a sword grip, the lean into a sprint, the recoil from a hit on the left shoulder — is procedural. In Godot 4.6.3 this is done via the SkeletonModifier3D family attached to the Skeleton3D, plus tween-driven additive blend layers on the AnimationTree. None of it is generative; this skill is a recipe set.

Honest limit: Godot 4.6.3's IK is good enough for look-at, foot-snap, and simple two-bone arm/leg chains. It is NOT good enough for full-body IK with weight redistribution (a la UE5 Control Rig). For combat-grappling or contact-heavy interactions, hand-author the contact frame and accept some clipping.

When to use this skill

• Feet clip into / float over uneven terrain.
• NPC head doesn't track the player during conversation — feels dead-eyed.
• Character's hand doesn't actually hold the sword — pen-through.
• Body doesn't lean into turns / aiming.
• Hit reactions need to come from the hit direction (recoil left when struck left), not just one canned animation.
• Ragdoll on death.

When NOT to use this skill

• The clip already covers it. Don't IK what mocap already nailed — adds CPU cost and rounding error.
• The character is far from the camera (LOD2+). Procedural cost outpaces visual benefit. Disable modifiers past 15m.
• You need facial animation. That's onyx:animation/facial-and-lipsync.
• You haven't generated base clips yet. Skeleton modifiers compose ON TOP of clips; without a base pose they'll stack on T-pose and look wrong.

The three patterns

Almost every procedural request maps to one of these three. Pick the right one before writing code.

Pattern A — SkeletonModifier3D (post-clip bone overrides)

Attached as a child of Skeleton3D. Runs after the AnimationTree writes the pose, modifies specific bones in-place. Includes LookAtModifier3D, SkeletonIK3D (legacy, still supported), and the new (4.4+) LookAtModifier3D chain. Cheap, deterministic, no animation graph dependency.