Cut the Curve — the technique catalog Five SEAM techniques, one principle: cut at peak velocity, match direction and speed on both sides of the cut — plus the two in scene techniques (§6 arrivals, §7 slides). The seam LAW — vector law, the current, the ledger, the Seam Gate — lives in motion doctrine ; read it first. This skill is the parameters and mechanics. All GSAP code templates (worker + registry): examples/gsap implementation.md . Catalog Technique Scope Axis Use for 1 Zoom Through (forward) Within scene text swap Z, toward viewer progressing deeper into the same thought 2 Inverse Zoom Through Arrival / payoff beat Z, away from viewer something bigger lands 3 Cut the Curve Between scenes X / Y the default boundary, the film's current 4 Waterfall Cut Text to text seam X, per word word level handoff between big text beats 5 Rack Focus Blur Cut Same surface state swap X / Y / Z the one cut you want SEEN — a DSLR focus pull flourish 6 Waterfall Entry In scene ARRIVAL (no seam) Y, from below title cards, segment openers, list intros 7 Nudge Curve In scene group slide (no seam) X / Y repositioning a composed group to make room Z direction is a sign "Same axis" is not enough on Z — the sign of d(scale)/dt must match across the cut: Z vector Exit scale Entry scale Variant Push (forward) growing 1 → 1.2 growing 0.75 → 1 zoom through Pull (back) shrinking 1 → 0.8 shrinking 1.25 → 1 inverse zoom through Banned mirrors: a receding exit answered by a grow from small entry (pull flips to push — the common one, since grow from small is the default element entrance), and a push exit answered by an oversized retraction. This binds the incoming scene's OWN entrances during the seam window (cut + ~0.5s), not just the wrapper tween: hold the incoming frame composed, or author its entrance to match the sign. Verify per Seam Gate rule 7. Blur logic (all Z variants) Subject Peak blur Why Text scale (headline, word group) 10px 20px smears letterforms — the cut reads as a glitch, not speed Full frame surface (window, card, screenshot) 18–20px lighter blur on a big surface reads as a rendering hiccup Same peak blur on both sides at the swap frame. Blur the WRAPPER, never children. 1. Zoom Through (forward) Z axis velocity matched cut; never both texts visible. Everything GROWS: the outgoing text accelerates toward camera, a hard swap hides at peak blur, the incoming text keeps growing into the focal plane. Headlines and short phrases only. Total ≈ 0.4s. Phase Scale Blur Opacity Ease Duration Exit 1 → 1.2 0 → 10px 1 → 0.15 power3.in (opacity: separate none tween) 0.2s Cut ( tl.set ) in: 0.75 10px out: 0 / in: 0.15 — — Entry 0.75 → 1 10 → 0px 0.15 → 1 expo.out 0.5s Exit opacity MUST be its own linear tween — power3.in holds opacity near 1 too long. On entry all properties share expo.out . 2. Inverse Zoom Through (backward) The pull back mirror: the outgoing element RECEDES; the incoming arrives OVERSIZED (as if just behind camera) and retracts into the focal plane. Everything SHRINKS. Spend on ARRIVAL/payoff beats — a payoff line, a giant reply, a held end state — never ordinary boundaries. Total ≈ 0.7s (30% exit / 70% entry). Phase Scale Blur Opacity Ease Duration Exit 1 → 0.8 0 → 10px 1 → 0.15 power3.in (opacity: separate none tween) ~0.2s Cut ( tl.set ) in: 1.25 10px out: 0 / in: 0.15 — — Entry 1.25 → 1 10 → 0px 0.15 → 1 expo.out ~0.5s Blur is 10px text scale; 18–20px only when both sides are full bleed surfaces. Sign discipline: the incoming scene arrives as a composed frame inside the retracting wrapper — no grow from small intro in the seam window. Staged entrances happen after the retraction settles, or start ≥1 and retract. 3. Cut the Curve (default scene boundary) X/Y velocity matched cut — the default for ALL scene to scene boundaries, in the film's current, not an accent. The outgoing hero accelerates in one direction, the cut lands mid motion, the incoming hero continues the SAME direction and decelerates. Total ≈ 0.6s; directions LEFT / RIGHT / UP / DOWN (default LEFT). Partial travel: ~12% of frame (≈230px at 1920) — never full off screen moves. Direction Exit Entry start → end Leftward x: 0 → −230 x: +230 → 0 Rightward x: 0 → +230 x: −230 → 0 Upward y: 0 → −230 y: +230 → 0 Downward y: 0 → +230 y: −230 → 0 Mechanics: Mirrored eases: exit power4.in + entry power4.out , same distance and duration — the two halves of one power4.inOut , so velocity matches exactly at the cut. The fade trick: exit opacity completes at ~25–30% of its travel (fade ≈ 0.18–0.3s vs motion 0.3–0.34s); entry ignites at ~0.35 opacity mid path. Time the last fading element to die right at the cut — a gap where nothing moves reads as dead air. Exit 0.2–0.4s; entry ≥ exit. Optional blur 8–10px. Stage ground: root must be opaque ( background: var( canvas deep, var( canvas, 000)) ) — the mid window cut opens a summed opacity < 1 window that flashes white otherwise (see seam craft ). push slide exists but violates partial travel and mid motion phase; prefer cut the curve. 4. Waterfall Cut (word by word cut the curve) Cut the curve at WORD granularity — the strongest leftward cut for text to text seams. Outgoing words ramp out on their own curves; incoming words cascade in mid flight — a wave the eye rides across the seam. Scope: worker authored inside one multi beat comp (stacked full frame .beat layers), NOT a registry/injector type — it tweens word spans, not clip wrappers. The boundary into and out of the text beat block still gets a normal registry transition. Does not count against the 2–3 transition budget. Parameter Value Why Travel ±230px (~12% frame) partial travel + velocity full frame push Exit 0.34s power4.in the acceleration IS the cut Exit fade 0.18s, starts with x word gone by ~25–30% of travel — no smear Exit stagger +0.022s reading order the line peels, not a block slide Entry 0.3s power4.out back half of the composite — velocity match Entry start opacity 0.35 mid path ignition; binary 0→1 pops Entry gaps 0.05s × 0.84 decay accelerating cascade, resolves composed Rules: One direction per chain, riding the current. Inverse zoom is the chain's ARRIVAL beat only. Pre set all words to x: +230, opacity: 0 at build time — immediateRender: false alone leaves un started words visible at rest. A short first beat may exit whole line: its fade ends ~0.02s before the cut so it is still streaking when the next words ignite — no dead gap. Transform/opacity only (seek safe); opaque stage ground applies. 5. Rack Focus Blur Cut (the visible cut) The one variant where the cut is SEEN: a defocus blur SPIKE hides a single frame hard swap — a handheld DSLR focus pull. Use as an occasional flourish for a state swap of the SAME surface within one visual theme; never the default boundary. Differences from the others: outgoing stays FULLY OPAQUE until the cut (the blur hides the swap — no early fade); eases power2.in / power2.out (soft optics, not momentum). Rules: Fire only at a narrative beat, ≤ once per ~8s; never mid caption or during a hold. Cut at PEAK blur (≥6px; peak 8–12px, ≤16–18px max) — swapping on the way up shows the cut. A subtle scale (~1.06 lens breathing) sells it as optics. Same direction on both sides — the vector law still holds. Entry ≥ exit duration. Blur the wrapper; never blur + opacity in one tween on one element (headless compositing bug); never blur a <video directly (wrap it). 6. Waterfall Entry (in scene arrival — not a seam) Staggered ARRIVAL cascade: words/elements whip in from below (one consistent direction), each starting before the previous settles — an accelerating wave that resolves into a composed layout. Title cards, segment openers, list/feature intros. The seam sibling is §4; do not mix their rules: §6 Entry (arrival) §4 Waterfall Cut (seam) Opacity BINARY 0→1 via tl.set at entry — never fade ignites at 0.35 mid path — the fade IS the velocity trick Axis default Y, from below X, riding the current Outgoing side none words ramp out on mirrored power4.in Choreography: Overlap, don't queue — next element starts within ±2 frames of the previous settling; gaps SHRINK across the cascade; the last element snaps. Velocity varies by weight — heavy/anchor elements travel further and longer; light words/punctuation snap in tight: Parameter Anchor/heavy Normal word Light/punctuation Y offset 60–80px 40–50px 30–48px Duration 0.16–0.20s 0.13–0.16s 0.10–0.13s Overlap 0–2f gap 1f overlap 1–2f overlap Ease power4.out (expo.out for extra snap); never .inOut on an entry. One direction per cascade. Split the FINAL word into fragments to extend the climax; fragments travel further. Post settle, the group usually slides to make room for the next beat — that's §7. 7. Nudge Curve (in scene group slide — not a seam) Slow fast slow repositioning of a composed group (word rows, card stacks, lists) to reveal content or make room. No single built in ease produces it — power4.inOut smacks to a stop. Chain three tweens on one property: Phase Ease Distance Time Feel 1 ramp in power3.in ~10% ~20% barely moves — motion registers, no jolt 2 burst none (linear) ~65% ~18% ~2× average px/frame — purposeful 3 tail power4.out ~25% ~62% decaying creep to rest — kills the smack Rules: The tail is ≥3× the ramp in in TIME. If it still smacks: extend the tail's time (not distance) or use power5.out . Phase 2 stays linear — easing it loses the burst contrast. Reveal new content DURING phase 2 — the burst masks its appearance. Same ratios vertical; scale distances proportionally, keep the time ratios. Choosing a Variant

cut-the-curve