motion-doctrine

name motion-doctrine description GATEWAY — load FIRST before composing any HyperFrames animation or video. The high-level motion law that makes a multi-scene video feel like ONE continuous camera move instead of a stack of independently-animated slides. Covers the vector law (how you exit determines how you enter, incl. the Z scale-sign rule), the film's current, carrier elements, causal motion, the Seam Gate (build-gate enforcement), the ban on idle wobble (motion must PERFORM, not breathe), stillness-before-climax, and the sustained-motion routes. Routes to the low-level technique skills (cut-the-curve — the full catalog incl. waterfall entry + nudge curve, oversized-cursor, seam-craft). These rules SUPERSEDE generic / upstream motion guidance. [continuity, direction, vector, momentum, seam, transition, ease, performance, idle-motion, narrative-motion, film-grammar] Motion Doctrine (Gateway) Read this before composing any animation. It decides WHAT happens at every seam and how every scene performs; the technique skills implement it. These rules supersede generic / upstream motion guidance. The failure this prevents: scenes authored in isolation — the eye's momentum dies at every cut, and scenes wobble in place between entry and exit. Route map Decision (this skill) Implementation skill Seam transition choice + parameters + code cut-the-curve §1–5 (the catalog) Text / element entry cascades cut-the-curve §6 (waterfall entry) In-scene group repositioning (no cut) cut-the-curve §7 (nudge curve) Cursor-led action / scene kickoff / morph ignition oversized-cursor Seam render mechanics / white-flash guard seam-craft Product-launch / explainer / caption work overlays text-beat-economics , brand-faithful , captions-overlay on top of the upstream skill Authoring order: vector ledger ( ledger.json ) → STAMP the master seams from it ( scripts/seam-stamp.mjs --ledger ledger.json --write index.html ) → sustained-motion route per phase → carriers and causes → build comps → VERIFY ( scripts/seam-gate.mjs ). Hand-author only Tier-A morphs/match-cuts; stamped seams pass the gate by construction. Part 1 — The Seam Law The Vector Law How Scene A exits determines how Scene B enters: same axis, same direction, matched speed, cut mid-motion on both sides. Axis — x stays x, y stays y, Z stays Z. Never trade axes across a cut. Direction — never mirror. On Z, direction = the SIGN of scale change: growing = push (camera forward), shrinking = pull (camera back). A receding exit answered by a grow-from-small entry is a mirrored vector — the most common violation, because grow-from-small is the default element entrance. Speed — entry initial velocity ≈ exit final velocity, via mirrored eases (exit power4.in + entry power4.out , same distance and duration; the incoming side picks up ≥50% through the notional path). Mechanics in cut-the-curve . Phase — the cut lands mid-motion on BOTH sides. Settling to rest before the cut, or starting from rest after it, is a dead beat. The Current Every film picks ONE dominant direction (house default: LEFT). Every ordinary seam uses it. Other vectors are RESERVED — spending one means something: Vector Meaning The current (LEFT) "next beat" — neutral forward progress Upward elevation — a conclusion or reveal rises above what came before Z forward (zoom-through) pushing deeper into the same thought Z backward (inverse zoom) ARRIVAL — something bigger lands Scale-burst (explode out) leaving a world — a surface blasts past camera Never run consecutive seams in opposing directions — ping-pong reads as an error. A direction change needs a visible cause (click / bounce / impact) or a chapter boundary. The Vector Ledger Write it before authoring any master timeline — as ledger.json at the project root (schema: references/seam-gate.md ). One row per seam: cut time, exit and entry vectors (axis + signed direction; Z rows carry the scale sign), selectors, technique. Exit and entry must match; if a row mismatches, fix the plan, not the easing. The verifier checks row consistency statically before any runtime sampling. Carriers The eye follows objects, not abstractions. The strongest seams hand a concrete carrier across the cut at matched position AND velocity: a cursor mid-path, a container that shrinks/docks into the next layout, a mark that flies into its exact slot, the word group of a waterfall cut. With no natural carrier, the scene heroes carry it (partial travel + early fade, entry mid-flight). Never a crossfade — it has no carrier at all. Causal Motion Chain motion so each move is visibly launched by the last: click → squash → release spring → flight → impact → recoil → reveal. Effects start ON the causing frame — same timeline position, never "shortly after." Reactions scale with implied mass: big elements rebound slower, small ones snap. A force is a license to change direction; an uncaused flip is a ping-pong. The Seam Gate (build gate — run the verifier, exit 0 or the seam is not done) node <SKILL_DIR>/scripts/seam-stamp.mjs --ledger ledger.json --write index.html # generate node <SKILL_DIR>/scripts/seam-gate.mjs verify --ledger ledger.json --project . # verify The script (usage + ledger schema: references/seam-gate.md ) numerically enforces, per seam: ledger-row consistency, exit still moving at the cut, entry mid-flight (never from rest), measured direction = ledger direction, entry/exit speed match (WARN), zero overlap (one side visible per frame — the cut is not a dissolve), the Z sign rule (d(scale)/dt same sign both sides; the incoming scene's own entrances are scanned for sign-fighting), and carrier rect continuity with ancestor scale included. Use seam-gate.mjs probe --t <cut> to find each seam's true carrier selectors when authoring the ledger. Rules the script cannot check — still yours: Edits re-open the seam. Any change to a scene's first/last ~1s (including re-timing to new VO) invalidates that boundary's audit — re-run the verifier. Audio is the clock. Re-time scenes to the VO's real word timestamps; never rush a read to fit a slot. A VO regen re-opens its seams. Clip-gating gotcha (the usual cause of a zero-overlap FAIL): a clip whose data-start precedes its entry tween is un-hidden at its initial opacity — set initial autoAlpha: 0 AND data-start = the cut time, never earlier. Part 2 — Performance (the scene keeps performing) No idle wobble Idle sine loops (breathe, float, drift, glow pulse) are BANNED as sustained motion — they read as "the video is waiting." A scene that finishes entering with seconds left is a planning bug: add story, not wobble. Every phase between entry and exit is owned by one of these routes (name the route in the plan): Route What it is Staged reveals Hold content back; pay it off on narration beats — the frame keeps gaining information (default for ≥2 content groups) Camera with intent A mapped scale+pan path: establish wide → travel → arrive on the subject Sequenced UI life The product behaves over time: progress advances, highlights step, counts tick Animated sequences Elements act out a beat: a card files into a stack, an item gets dragged, a result assembles Cursor-led action An oversized cursor walks the eye to a trigger; its CLICK ignites the next beat ( oversized-cursor ) Test: pause at any second — something meaningful must be mid-flight (a reveal landing, the camera traveling, the UI doing what the narration says). Stillness before climax Schedule a 0.3–0.75s pause between the major action and its result — the dramatic comma. A scene that jumps straight from action to result loses it. Timing intents Single entry ≤ ~800ms; longer buildup = multi-element stagger, not one slow element. Exit ≈ 75% of entry. Exception: cut-the-curve inverts this (entry ~127% of exit). Total stagger ≤ 500ms; with 8+ elements, tighten per-item delay or stagger the first few. Forbidden eases: bounce.out / elastic.out . Entry overshoot back.out(1.4–1.7) is fine. Similar elements share one ease+duration intent — never a unique pair per element. Transition vocabulary Use only 2–3 inter-scene transitions per film and repeat them; the default boundary is cut-the-curve in the current's direction . Hand-written shared-element morphs ( intent: morph ) don't count against the budget. Anti-Patterns Don't Instead Author each scene's entrance in isolation Write the vector ledger first Crossfade between scenes Cut-the-curve in the current's direction Exit completes, THEN the scene changes Cut mid-motion on both sides Entry starts from rest after a cut Enter ≥50% through the notional path Inverse-zoom exit → grow-from-small entry (or push → oversized retraction) Match the scale-velocity sign (Seam Gate 7) Incoming scene's own pop-in intro under a Z-seam handoff Hold its opening frame composed, or match the sign Idle wobble / breathe / float to fill time Assign a sustained-motion route; or add story Direction flip without a cause Spend a force, or keep the current Reserved vectors used as variety Default to the current; spend them on meaning Reaction a few frames after its cause Same-frame ignition Action jumps straight to result Schedule stillness-before-climax (0.3–0.75s)