Blender animation (character and object)

Expert animation means every frame on screen is a choice: key poses the audience reads, holds and snaps placed by hand, spacing designed, arcs checked. The Blender Studio stance is to block stepped, spline late and in parts, and judge from the shot camera at real speed. An agent cannot scrub, so it measures instead: per-frame positions, spacing charts, arc checks, framing, an onion-skin image, a curve plot, and a playblast it actually looks at. If a sibling skill named here is missing from your available skills, ask the user to install it (npx skills add scenario-labs/skills --skill <name>); unattended, proceed from tool schemas and flag the gap.

REQUIRED BACKGROUND: scenario-blender-expert (execution channel, review loop, 5.2 API changes). Shot planning, cameras and animatics belong to scenario-blender-previs-storyboard; building the rig to scenario-blender-rigging.

Toolkit: scripts/bx_anim.py (keying, blocking-to-spline, curve checks, measurement, staging, playblast light, knee-pop, flip and balance checks, onion-skin and curve images, one-object bouncing_ball; API in procedures.md, tested on 5.2.1) and bx_review.playblast.

Stance (the expert delta)

• Stay stepped long ("Blocking+"). Hjalti Hjalmarsson: juniors spline too early; computer in-betweens are "unintentional interpolated poses" that make notes hard. Keep adding hand-made breakdowns while stepped; splining is short and late.
• Never convert the whole blocking to Bezier. Rik Schutte: key every main control on every key pose, copy each pose to the end of its hold ("pillars"), then spline the body only; face and fingers stay stepped until their own pass. Measured on 5.2.1: the naive conversion drifted 84% of the next move across a hold, the pillars held at exactly 0.
• Snaps are authored. Rik: hold, then change pose in 2 to 3 frames; only big deliberate moves are left to interpolation. [added, measured] A contact inside continuous motion (a jump landing) is not a hold: pillaring it cut the body's speed at impact from 0.101 to 0.007 m per frame, a floaty landing.
• Odd frames, even gaps; breakdowns shape arcs and steer the eye. Alex Nagy: key poses on odd frames with even spacing so a true middle frame exists. The breakdown sets the arc first, the timing second; favoring it late leaves more travel for the last frames, and the fastest part draws the eye.
• The handle type is a timing decision. AUTO_CLAMPED keeps holds flat; AUTO overshoots between two equal keys (Alex uses it to push a pose or cushion a settle); VECTOR for hard hits, contacts and take-offs (Alex, Dillon Gu); FREE for burst spacing and exact arcs (Raymond Luc, Joey Carlino).
• Lead with one part, layer the rest. Rik blocks a torso-only rhythm pass first; Dillon leads body mechanics with the COG and acting with the head or eyes. Overlap goes into the blocking, and a head never turns on one axis only (Rik).
• Lip sync is rhythm before shapes. Rik: jaw first, stepped, opened big only on accents; off-sync is a missing preparation, not a global offset; M, B, P closed at least 2 frames and closed before the sound.
• Spacing is felt, arcs are checked, the shot must read. Raymond: the audience should feel spacing tricks, not see them. Pablo Fournier: arcs are the most important check (root, hands, feet, nose), in camera space. Hjalti (in scenario-blender-previs-storyboard): after each cut the eye must find one thing, so a subject lost in an empty frame fails however good the curves are.