Wake up

The task says "Wake up and do as you please." My purpose is to create cool Three.js demos in my space under /space/demos/. Let me check the current state of the demos folder, then create a new advanced demo and update the index page.

Let me first install shell tools and check what's in the demos folder.

Let me check the current state of the demos folder.

There are 53 demos. I should create demo 054. Let me look at the last demo (053-caldera) briefly to understand style/quality, and check the index page structure so I can add a new card properly.

Let me look at what demos exist to avoid repeating concepts:

• 001 spinning cube
• 002 nebula galaxy
• 003 mandelbulb explorer
• 004 fluid dynamics
• 005 gravity sandbox
• 006 event horizon
• 007 sonic reactor
• 008 void runner
• 009 azure odyssey
• 010 abyssal bloom
• 011 physarum garden
• 012 powder alchemy
• 013 clockwork nebula
• 014 neon rain
• 015 aurora borealis
• 016 skitter
• 017 coral resonance
• 018 threshold
• 019 attractorium
• 020 murmuration
• 021 terraforge
• 022 cloudsea
• 023 frostline
• 024 koi pond
• 025 ferrofluid
• 026 synchrony
• 027 cymatics
• 028 teslasphere
• 029 pyrosymphony
• 030 morphogenesis
• 031 galton cascade
• 032 wavefront
• 033 gossamer
• 034 magnetosphere
• 035 cloud chamber
• 036 wavefunction
• 037 epicycle
• 038 sandpile
• 039 kinetic theory
• 040 lumen lab
• 041 squish lab
• 042 neon tilt
• 043 hyperfold
• 044 photon garden
• 045 critical point
• 046 bridge works
• 047 primordial
• 048 coasterworks
• 049 sakura grove
• 050 voxelia
• 051 neon district
• 052 supercell
• 053 caldera

I need a fresh idea for 054. Ideas not yet covered:

• Lightning storm / electric arc simulation (teslasphere covers some)
• Ocean wave simulation with Gerstner waves and foam (cloudsea is clouds, koi pond is water-ish)
• Origami / paper folding
• DNA helix / molecular
• Pendulum wave / harmonograph (epicycle is orbital, synchrony is metronomes?)
• Volumetric god rays through a forest
• Portal / non-euclidean
• Cloth simulation with tearing (gossamer may be cloth/spiderweb?)
• Ink diffusion / watercolor in 3D
• Topographic contour lines animated
• City traffic flow simulation (neon district is a city)
• Ant colony / termite mound
• Crystalline growth / dendrite (frostline may be frost)
• Solar system / orrery (epicycle)
• Wave interference ripple tank (wavefront, cymatics related)
• Double pendulum chaos
• Pinball machine 3D with physics
• Marble run / rolling ball sculpture
• Tetris 3D
• Boids underwater with caustics
• Bioluminescent deep sea
• Tornado of debris (supercell is storm)
• Raytraced spheres with reflections (lumen lab is optics?)
• Holographic globe / earth data viz
• Space elevator
• Procedural tree growth / L-systems (sakura grove is trees)
• Music piano roll 3D
• SPH water in a glass
• Melting / wax
• Smoke rings / vortex
• Glitch art / datamoshing
• Fractal fern
• Voronoi shattering / destruction
• Softbody blob (squish lab)
• Domino chain reaction in 3D — physics demo, fun, not done yet!
• Rube Goldberg machine
• Wrecking ball destruction
• Tensegrity structure
• Quantum foam
• Neural network visualization in 3D — neurons, signals propagating, interactive. Not done yet! "synapse" theme.
• Fireworks show over a city/water with reflections (pyrosymphony is fire-related, maybe)
• DNA / protein folding
• Harmonic pendulum wave — mesmerizing, simple physics, beautiful with bloom. Synchrony might be pendulums though (metronome sync?). Let me check what synchrony is.

Let me check a few to avoid overlap. Let me quickly look at synchrony, pyrosymphony descriptions from index.html.

Actually, let me grep the index.html for titles/descriptions of recent ones to make sure my idea is fresh.

Ideas that feel strong and not done:

1. 3D Domino Rally — physics-based dominoes with a course builder, chain reactions. Uses cannon-es or custom simple physics. Interactive: click to topple, drag to place.
2. Neural network / synapse visualization — "Synapse Garden"?
3. Holographic Earth with data arcs.
4. Ripple tank with wave interference — done-ish (wavefront).
5. Pendulum wave machine with bloom and trails — "Pendulum Wave" / "Harmonograph 3D".
6. Marble run — physics marble through procedural track.

Let me check the index descriptions quickly for synchrony and pyrosymphony, then decide.

****************************************************************************************************************************************************************************s).

Good, I understand the conventions: three@0.160.0 with import maps, self-contained index.html, HUD panels with monospace font, generative WebAudio, etc.

Now for the new demo 054. Idea: "Domino Rally" — a 3D domino chain-reaction playground with custom physics. Or something else fresh. Let me think about what's most impressive and feasible in a single file:

Option A: Domino Rally — procedural domino courses, custom lightweight rigid-body physics for dominoes (boxes colliding), click to topple, chain reactions, slow-mo. Physics of many boxes is doable with a simple impulse-based solver, but robust box-box collision in vanilla JS is tricky. Could use a simplified approach: dominoes rotate about their base edge when hit (hinge model) — this is actually a well-known trick: each domino is a rigid body with rotation around its bottom edge; collision triggers angular impulse on the next domino. This produces very convincing domino chains without a full physics engine. I can build tracks: spiral, lines, splits, bridges. Click a domino to push it. This is fun and visually satisfying. Add confetti particles when the last one falls, sound clicks (WebAudio).

Option B: Pendulum Wave — 15 pendulums with slightly different frequencies creating mesmerizing patterns; with bloom trails. Simpler, might overlap with synchrony (which I believe is metronome synchronization). Let me check the description of 026-synchrony in the index to be sure.

Option C: Fireworks over water — likely overlaps with pyrosymphony.

Option D: 3D marble run with procedural track.

Option E: Neural network / synapse visualization.

Option F: Volumetric fog forest with god rays.

Domino Rally sounds the most playful and interactive — a physics chain reaction demo. The hinge-based domino physics is very feasible and reliable. Let me design it:

Domino Rally — Chain Reaction Playground

Features:

• A scene with multiple procedurally generated domino courses: a long spiral, straight runs, Y-splits (one domino knocks two), maybe a "bridge" of dominoes going up steps.
• Physics: each domino is a box that can rotate around its base edge axis (perpendicular to fall direction). Two-state: standing or falling with angular velocity; when angle exceeds threshold past balance, gravity torque accelerates. Collision: when a falling domino's leading face sweeps past the position of the next domino, impart angular velocity to the next. For general placement, compute for each pair of nearby dominoes the trigger angle based on geometry. Actually simpler robust approach: precompute "hit graph" via geometry: when domino A rotates to angle θ_hit where its top edge reaches domino B's position, transfer momentum. Compute reach: domino height h, its tip sweeps a circle of radius ~h around base edge; if domino B is within reach in the fall direction, trigger when A's angle θ satisfies h*sinθ >= distance to B (projected). Then give B angular velocity proportional to A's angular velocity and contact geometry.

That works for chains, splits, and curves (fall direction = direction to next domino... but each domino has its own orientation; the domino falls in the direction of its local +Z (its thin axis). When hit from behind, it falls forward. For precomputed triggers, fall direction per domino = its orientation's forward. If hit pushes it, it falls forward. Good.

• Also add ball runs? Keep it domino-only for focus.
• Interactions:
  • Click any domino to push it (raycast), it falls in its forward direction (or away from camera? forward).
  • "Drop all" button? Actually a big red "TOPPLE" trigger that pushes the first domino of the main course.
  • Reset button to stand them all back up with a fun reverse animation.
  • Camera: OrbitControls plus a cinematic "follow the wave" mode where the camera tracks the falling front.
  • Sound: WebAudio click/clack sounds on each domino impact, pitch varying; a low thud when domino hits the floor.
  • Particles: small dust puff/spark at each impact; confetti burst when the course completes.
  • HUD: fallen count / total, chain speed, FPS maybe. Buttons: Topple, Reset, Follow Cam, Sound toggle, Add chaos mode (wind gusts?), course selector (Spiral / Snake / Cross Split).
• Visual: night environment, neon rim lighting, bloom (UnrealBloomPass), reflective floor, dominoes with emissive colored stripes — color gradient along the course so the falling wave looks spectacular.

Implementation details:

• Use three@0.160.0 import map, OrbitControls, EffectComposer + RenderPass + UnrealBloomPass + OutputPass.
• Domino geometry: BoxGeometry(0.6, 2.0, 0.28) roughly (thin box), pivot offset so rotation happens around bottom-front edge. Use a Group per domino: group at base position, rotated to heading; inner mesh offset so the hinge edge is at group origin. Rotation.x (local) controls fall.
• Fall physics per domino: state: angle θ, angular velocity ω. When standing, θ=0. If pushed (ω != 0 or θ > θ_balance ~ atan(thickness/height)), integrate: torque from gravity about the hinge: τ = m g (d/2)... For a box rotating about its bottom edge: I = (1/3)m(h² + t²). Center of mass at (t/2, h/2) relative to hinge (x = forward, y = up). Gravity torque τ = -m g x_cm_rel... Let me param: when rotated by θ forward, center of mass forward offset from hinge = (t/2)cosθ + (h/2) sinθ? Hmm, at θ=0 (standing), hinge is at front-bottom edge; cm is at (t/2, h/2): x_cm = t/2 > 0 (forward). So gravity torque about hinge tends to rotate it forward?? No — if hinge is the FRONT bottom edge and cm is behind the hinge (x_cm = -t/2 if +x is forward)... Let me define: domino falls in +x direction. Hinge = front-bottom edge at +x side? When falling forward (+x), the domino pivots on the front-bottom edge. The center of mass at standing is at (0, h/2) in body coords; hinge at (t/2, -h/2) relative to center... Let me set group origin at the hinge point on the floor: hinge at world base + forward*(t/2). Body center at local (0, h/2) when standing... wait hinge at front edge means center is BEHIND the hinge by t/2: center local = (-t/2, h/2). When the body rotates by θ about the hinge (falling forward, rotation about z-axis by -θ... ), center position = R(-θ)·(-t/2, h/2). x_cm = -t/2·cosθ + h/2·sinθ. Gravity creates torque τ = m g · x_cm (restoring while x_cm < 0, i.e., θ < atan(t/h), toppling when beyond). I_cm about edge = (1/3)m(h²+t²) (for rotation about edge: I = (1/3)m(a²+b²) for a rectangle about corner... yes, for a thin rod about end it's (1/3)mL²; rectangle about edge: (1/3)m(a²+b²)). So α = τ/I = g·x_cm·3/(h²+t²) with sign = m g x_cm / I, α positive when x_cm>0 → falls forward. That's a clean ODE: θ'' = (3g/(2(h²+t²))) · (h sinθ - t cosθ).

When θ reaches θ_max = angle where it lies flat: about (π/2 - atan(t/h))? When flat on face, the face rests on the ground: the body has rotated 90°+ a bit. Actually it comes to rest lying on its front face: rotation angle = π/2 - atan(t/h)?? Let's think: standing, rotating forward until front face touches ground. The front face is the plane at x=+t/2 spanning height h. After rotating θ=π/2, the face points down... but before that the bottom-front edge and the face contact... For a box falling about its front-bottom edge, it lands flat on its front face after rotating exactly π/2 (the front face becomes the bottom). But it could also bounce/settle. θ_max = π/2 works with the face flush on the floor — but note the hinge is the front-BOTTOM edge; after π/2 rotation the face lies on the ground, correct. To avoid z-fighting with floor maybe stop slightly before or rest at exactly π/2. Bounce: when hitting θ_max with high ω, do small restitution: ω = -ω·0.15 once, plus trigger "thud" and dust.

• Trigger detection: For domino i falling forward, check dominoes j whose position is within reach: distance d_ij from hinge_i to base of j projected. Tip of falling domino reaches forward distance = h·sinθ + (t stuff). Trigger when h·sinθ_i >= gap where gap = distance between hinge_i and the near face of j. Precompute pairs: for each domino i, find all j within radius h + t and with angle between i's forward and direction to j < ~60°. Record g_ij = projected distance from hinge_i to j's base minus t/2 (near face). During sim, if i falling and θ_i >= asin(clamp(g_ij / h, -1, 1)) → impact: impart to j: ω_j += k·(ω_i·h)/... scaled by contact height. Also reduce ω_i a bit. Also count dominoes hit.

For robustness in chain along curve: fall direction of each domino is its own local forward; when generating the course I orient each domino's forward toward the next domino. When j is pushed by i, j falls along j's own forward.

• Impulse transfer: contact height on j ≈ h·cosθ_i at tip... simpler: ω_j = 0.55·ω_i·(h_i/h_j) + 0.8 (min kick), plus set a small initial θ push. Fine-tune with constants. The key is it looks right: continuous accelerating wave.

• Multiple pushes: once fallen past balance, stays falling; ignore re-trigger.

• Sound: short noise burst / click with WebAudio on each impact; volume/pitch by ω. Floor thud: filtered noise burst low. Crowd-pleaser: rising pitch arpeggio as chain progresses? Keep clicks.

• Confetti: when the "final" domino (precomputed endpoint, or when 98% fallen) falls, burst of instanced quads with gravity.

• Camera follow mode: compute "wavefront" = most recently fallen domino index position; lerp camera target to it and position offset.

• Course generators:

  1. Spiral (phyllotaxis or Archimedean) — classic.
  2. Snake grid (boustrophedon rows) — long waves.
  3. Branch: main line splits into two lines forming a Y (trigger radius handles splits since multiple j within cone). Also a circle "bloom" at the end where dominoes fall outward radially. Maybe one course with a "steps" section where dominoes go up a small staircase (each next domino higher by step < t... trigger geometry: hinge height differs — include base height in reach calc: tip world height = base_i.y + h·cosθ; require contact: g horizontal distance and j base y within [tip height]. Keep it flat to stay robust; skip stairs. Or include small ramps? Skip — robustness first, bloom and confetti give wow.)

Actually for extra wow, make the floor a big reflective disc/grid with subtle glow lines (grid shader), dark fog, and a soft spotlight. Dominoes colored along a rainbow gradient with emissive stripes that pulse as the wave approaches (highlight "armed" next dominoes). Nice touch: next-to-fall domino glows.

Course count ~400-700 dominoes, all instanced? Since each domino rotates individually, use one InstancedMesh and update matrices per frame for falling ones; standing ones static — but with 500 dominoes updating matrices every frame is fine. Simpler: InstancedMesh with per-instance color; recompute matrix only for active dominoes. Use instanceColor for gradient + emissive can't be per-instance with standard material... MeshStandardMaterial with instanceColor affects diffuse; emissive would be uniform. Alternative: custom onBeforeCompile adding per-instance emissive from instanceColor. Doable: add emissive = vColor * emissiveIntensity. With instanceColor defined, vColor exists when vertexColors... In three r160, USE_INSTANCING_COLOR defines vColor for color. I'll patch shader: material.onBeforeCompile — replace '#include <emissivemap_fragment>' with added totalEmissiveRadiance += vColor.rgb * uEmissive; guarded by #ifdef USE_INSTANCING_COLOR... vColor is vec3 or vec4? It's vec3 in color_fragment? Actually vColor is declared as vec3 vColor when USE_COLOR... hmm with instancing color, varying vColor is vec3. I'll write totalEmissiveRadiance += vColor * uEmissive; inside #ifdef USE_INSTANCING_COLOR? But onBeforeCompile string injection — I can just append #ifdef USE_INSTANCING_COLOR ... #endif. Hmm, but vColor in fragment: for instancing color, three defines varying vec3 vColor; via color_pars_fragment when USE_INSTANCING_COLOR or USE_COLOR. Yes: common chunk color_pars_fragment: #if defined( USE_COLOR_ALPHA ) varying vec4 vColor; #elif defined( USE_COLOR ) || defined( USE_INSTANCING_COLOR ) varying vec3 vColor; #endif. Good.

Glow pulse: uniform uEmissive global pulse + per-instance color. Also "armed next" highlight would need per-instance emissive variation — could encode in a second InstancedBufferAttribute (aGlow float). Add custom attribute: onBeforeCompile add attribute float aGlow; varying float vGlow; and emissive += vColor * (uEmissive + vGlow * uGlowGain). Update aGlow for the next few armed dominoes.

Bloom: UnrealBloomPass with threshold ~0.6, strength moderate. Emissive stripes via texture? Simpler: whole-domino emissive glow at low intensity (0.25) + glow boost. With dark scene and bloom it'll look neon. Maybe add a subtle stripe texture generated procedurally on canvas for the domino faces (like a center dot/stripe) — adds detail. I can generate a small canvas texture: dark face with a colored pip/stripe, used as map; instanceColor multiplies. Since instanceColor multiplies the map color, pips get tinted — fine.

Alternatively keep it clean minimal: matte dark dominoes with neon edge glow via emissive tint. The bloom + gradient is enough.

Floor: big circle mesh with custom shader: radial grid lines glowing subtly + fresnel-ish sheen, or use MeshStandardMaterial with a generated grid texture + high metalness for env reflections. Simple reflective look: use a MeshPhysicalMaterial with clearcoat? True reflections need Reflector — maybe overkill. Use dark standard material + the bloom from emissive dominoes + fog. Add a subtle grid via canvas texture.

Lights: hemisphere + key directional with shadows (shadow map for 500 instanced boxes is fine) + a few colored point lights for vibe. Shadows: PCFSoft, 2048 map, camera bounds around course.

HUD (matching style of previous demos): title panel, buttons: TOPPLE (space), RESET (R), camera mode toggle (C), sound toggle (S), course cycle (N). Stats: fallen count, speed (falls/sec), elapsed. Bottom hint bar: "click a domino to push it · drag to orbit". Big "CHAIN COMPLETE" banner + confetti when all fall.

WebAudio: AudioContext lazily created on first interaction. Click: oscillator square short decay + noise; vary pitch with index for musical run. Actually make pitch follow a pentatonic scale ascending along the course → the chain plays a melody run! That's a delightful touch: each domino's click pitch = scale degree of its index → chain reaction becomes a glissando.

Also low thud on landing with slight randomization. Master gain + compressor to avoid clipping.

Reset: animate dominoes standing back up in reverse order (wave reverse) — visually fun.

Extra interactivity: "Gust" button that randomly pushes a few dominoes? Keep: click any domino to push it (choose direction = away from camera or its own forward; use its forward; if it's mid-fall ignore). Also allow "quake" that pushes random ones.

Course designs (cycle with N):

1. "Spiral Bloom": Archimedean spiral inward then a radial sunburst at center; final domino at center triggers confetti. Domino forward = tangent of spiral toward next; at sunburst, forward = radial outward? The center domino knocks a ring outward. The ring needs each ring-domino oriented radially with next outward one. To keep triggers simple, the burst can be a single ring of ~24 dominoes each falling outward (their forward = radial). The last spiral domino hits the first... hmm, hitting a ring from one point: the last spiral domino at center hits the 3-4 nearest ring dominoes (cone trigger handles it), each ring domino falls outward into... nothing further, or into an outer ring (second ring). Two concentric rings: inner ring falls onto outer ring. That works with cone+reach triggers as long as spacing < reach.
2. "Serpent": boustrophedon rows across a square — long parallel waves, satisfying.
3. "Twin Split": main line that hits a splitter domino which knocks two diverging lines that later converge at a "finale cluster". Splits work naturally with cone triggers (one domino in reach of two). Convergence: two lines' last dominoes both reach a final big domino.

Maybe include one giant "finale domino" (scaled up 2.5x) at the end that falls with a deep boom + confetti. Trigger reach uses its own size; bigger h → bigger reach. Falling giant onto floor = camera shake.

Scale handling: keep per-domino h, t, w; ODE uses h,t. Mesh scaled per instance via matrix (scale in matrix). Giant finale: h=4.5, t=0.6, w=1.6. Camera shake when it lands.

Structure code cleanly:

• init(): renderer, scene, camera, controls, composer, lights, floor, audio, UI bindings.
• buildCourse(index): clear group, generate array of {pos, heading, h,t,w, color, isFinale}, compute triggers list per domino (indices + triggerAngle + contact info), create InstancedMesh (max count fixed e.g. 1200; set count per course), set matrices+colors, aGlow attribute.
• update loop: integrate active dominoes, check triggers, check landing, update matrices (compose from pos + headingQuat * rotationX(θ) with hinge offset), update glow for next N upcoming (based on recentlyFallen wavefront: dominoes within radius of wavefront get glow), camera follow, HUD.
• Domino matrix: hinge at world position P (base center). We rotate about the front-bottom edge. Build matrix: T(P) · R_y(heading) · T(t/2, 0, 0)?? Let's define local frame: forward = +X after R_y(heading). Hmm simpler: choose local forward = +Z, geometry BoxGeometry(w, h, t) centered; hinge offset = (0, -h/2, t/2) in body space (front-bottom edge line runs along X). Rotation about X axis by θ (falling forward = rotate around hinge line parallel to X). Matrix per domino: M = T(basePos) · R_y(heading) · T(0,0,t/2) · R_x(θ) · T(0, h/2, -t/2) · S? Let's verify: we want hinge point at world base + forward·(t/2). Body center relative to hinge at θ=0: (0, h/2, -t/2). So: place body so that hinge is origin, then rotate about X (hinge axis along local X), then translate hinge to its position (base + forward·t/2), then heading rotation, then base translation. Order (column-vector): M = T(base)·Ry(heading)·T(0,0,t/2)·Rx(-θ)... sign of rotation: falling toward +Z (local forward) is rotation about +X by +θ? Rotating a point (0, h/2, -t/2) about X by +θ: y' = y cosθ - z sinθ... using right-hand rule about +X: y' = cosθ·y - sinθ·z; z' = sinθ·y + cosθ·z. With y=h/2, z=-t/2: z' = sinθ·h/2 - cosθ·t/2 → for small θ>0, z' increases from -t/2 → moves forward (+Z). Yes Rx(+θ) tips it forward.

So matrix = T(base) · Ry(heading) · T(0,0,t/2) · Rx(θ) · T(0, h/2, -t/2) · (scale for giant ones: bake h,t,w into geometry? Use unit box and scale — cleaner: BoxGeometry(1,1,1) and scale (w,h,t) in matrix: last factor S(w,h,t), with offsets multiplied accordingly: hinge offset (0,0,t/2) and body offset (0,h/2,-t/2) are in scaled units... To keep it simple, apply offsets in scaled space then scale first: M = T(base)·Ry·T(0,0,t/2)·Rx(θ)·T(0,h/2,-t/2)·S(w,h,t). The translation components are world-ish units; scale only the box. ✔.

Compose with THREE.Matrix4 multiplications each frame for active ones (~ up to 200 active simultaneously) — fine.

Trigger computation: for domino i with hinge world H_i = base_i + fwd_i·t_i/2, tip sweep radius r_i = sqrt(h_i² + ... ) tip = top-front corner: distance from hinge = sqrt(h² + 0) hmm top-front corner is at hinge + (0,h,0) at θ=0, so sweep radius = h_i. Reach when tip's forward travel = h_i·sinθ and tip height = h_i·cosθ. Trigger on j when: horizontal dist from H_i to j's base center projected onto fwd_i: d = dot(base_j - H_i, fwd_i) - (t_j... near face of j is at its base center minus fwd_j·(t_j/2) but j may be oriented differently; approximate using base center minus t_j/2). Condition: d <= h_i·sinθ + 0.02 and tip height h_i·cosθ > base_j.y - 0.3 (can hit domino standing on higher ground only if tip above its base... j is hit if tip height ≥ base_j.y). Also lateral offset |cross| < (w_i/2 + w_j/2 + 0.15). Precompute for each i a list of {j, θ_trigger = asin(clamp(d_eff / h_i))} where d_eff = max(d - t_j/2, 0.05). During sim when θ_i crosses θ_trigger and j is standing: push j.

Push j: ω_j = max(ω_j, 0.6·ω_i·(h_i/h_j)^0.7 + 1.2). Also mark j active, play click, spawn spark at contact point (approx midpoint), count++. Also damp ω_i *= 0.8 (energy loss). Small randomness in click pitch.

This will produce a beautiful accelerating wave. Chain speed stat: falls in last second.

Also push on click: raycast into instanced mesh (three supports raycast on InstancedMesh giving instanceId), push that domino with direction: its forward. If it's the giant, fine.

Confetti: instanced small quads (plane) with per-instance velocity, spin, color; burst from finale position; integrate ~3s, fade. Implement as InstancedMesh of plane with MeshBasicMaterial vertexColors... per-instance color via instanceColor; opacity fade globally. ~400 pieces.

Sparks/dust on impacts: a small Points pool (e.g. 600) with velocity+gravity, additive blending; spawn 4-6 per impact at contact. Fade by age. Cheap and juicy.

Camera shake: on giant landing, add decaying noise to camera offset.

Courses: I'll write three generators returning {dominoes: [{x,z,y,heading,h,w,t}], finaleIndex}.

Course 1 "Spiral Bloom": Archimedean spiral: r from R0=1.2 to Rmax~16, angle step so arc spacing ≈ 0.62 (trigger reach h=2, spacing 0.62 fine). Points p_k = (r cosφ, r sinφ), heading = tangent direction (toward next point) → forward. After spiral ends at center... actually start OUTSIDE going inward? Chain flows inward to center where finale giant stands, then giant falls outward onto a ring? Giant falling outward knocks an outer ring of dominoes radially... but ring dominoes' forward must be radial outward; the ring is INSIDE the spiral start? Getting complex. Simpler: spiral from outside inward; at center a giant domino; the last spiral domino hits giant; giant falls in ITS forward (radially outward along last tangent? set giant forward = direction from second-to-last to giant → continues line). Giant lands with boom + confetti. Also add center ring around giant: 10 small dominoes in a circle around giant at r=1.6, each forward tangential; the last spiral domino knocks 1-2 of them, they chase around the circle (circle of dominoes each hitting next = perpetual ring), and at one point the ring has an exit branch hitting the giant. Hmm — circle works: dominoes on a circle each oriented tangentially; chain goes around the full circle; last ring domino is adjacent to giant's near face and knocks it.

So Course 1: long spiral inward → into a small circle loop at center → last circle domino topples the giant → confetti. The spiral endpoint must connect into circle start: I'll generate spiral to r=1.9, then place circle dominoes r=1.55 from the entry angle around 300°, last one next to giant at center? Giant is AT center (base r=0). Ring domino reach h=2 vs distance 1.55 → trigger fine. Giant stands at center; final ring domino at r=1.55 knocks giant (giant near face at t_giant/2=0.3 from center → d_eff = 1.55-0.3=1.25 < 2 ✔). Giant heading: radial, falls outward onto the spiral path (visual collision with standing dominoes? It will visually clip through already-fallen ones — acceptable, they're fallen flat; giant falls on top — fine, no simulation of box-box resting; it'll land at θ=π/2 flat on face. Its face plane at floor level — might clip fallen dominoes under it slightly; acceptable at this stylization level. Or make giant rest angle π/2 - small. Fine.)

Course 2 "Serpent": rows: x from -14..14 step 0.62, rows z spaced 1.1? Trigger cone only checks forward-ish: at row ends, direction turns 180° pattern: domino at row end (x=+14, z=z_k), next at (x=+14+?, z=z_{k+1})... boustrophedon: at end of row, place domino heading +Z? To turn: last of row k at (14, z_k) heading +X; next at (14.6, z_k + 0.8)? The turn dominoes: one at (14, z_k+0.55) heading +Z+? Keep it simple: rows spaced 0.62 in x, row spacing 1.05 in z; at row end, place a corner domino at (x_end + 0.31·dir, z + 0.62) heading toward next row start... The heading of each domino = direction to next domino. Trigger checks lateral offset too. Turn geometry: A at (14, 0) heading +X. B at (14.62, 0) heading -Z? hmm.

Simplest robust snake: rows along X, spacing s=0.62; consecutive rows offset in z by dz=0.62 with diagonal connectors: A=(14, z_k) → B=(14.55, z_k + 0.55)... B must be within reach cone of A (forward +X, d=14.55-14=0.55 lateral 0.55 → angle 45° — inside 60° cone ✔ lateral limit w/2+w/2+0.15 = 0.75 ✔ borderline). Safer: cone 70°, lateral slack 0.35·h? Let me set lateral tolerance generous (0.5 + w). Since triggers are precomputed from authored courses, mild over-triggering is fine (it only fires when i is actually falling and θ crossing).

Even simpler snake turn: use an arc of 3 dominoes at each end (quarter circle, radius 0.9, 2 intermediate) — smooth turn, all spacings ~0.6. I'll do that: rows + semicircle turns of radius (rowGap/2) with 3 dominoes.

Course 3 "Twin Helix Split": main straight line → at midpoint a fork: one domino hits two (one veers left, one right) → two parallel lines that curve around a circle in opposite directions (clockwise/counterclockwise arcs) → meet at a finale gate where both hit the giant simultaneously. Circle arcs: place dominoes along two semicircles of radius 7 centered at the fork+ (forward) offset. Convergence point at opposite side where giant stands; both arc ends within reach of giant. Nice symmetry, looks great from above.

Also add subtle idle motion: standing dominoes get tiny glow pulse sweep traveling along course order (like "ready" wave) — uses aGlow.

HUD stats: total, fallen, falls/sec (rolling), best chain time. Banner on complete: "★ CHAIN COMPLETE ★" + confetti + chord.

Buttons: TOPPLE (Space) — pushes first domino; RESET (R) — reverse-wave reset animation; COURSE (N) — cycle 3 courses; CAMERA (C) — orbit/follow; SOUND (S); QUAKE (Q) — pushes 8 random standing dominoes (fun chaos).

Follow camera: target = latest fallen domino position; camera pos = target + offset rotating slowly. Blend factor smooth.

Audio engine:

• ctx, master GainNode + DynamicsCompressor.
• click(pitch, vel): osc square freq, gain env exp decay 0.06, + noise burst hp-filtered. Pan? Use StereoPannerNode by x position for immersion.
• thud(size): lowpassed noise burst + sine drop.
• finale: major chord arpeggio + noise riser.
• Pentatonic ladder: freq = 220 * 2^(degree/12), degree = index mapped across course → ascending glissando tied to chain progress (use order index along authored path: since courses are authored as ordered arrays, domino.index = position in array; but chain may not fall in order (splits); pitch by index still sounds musical).

Now write the code. Size: similar to other demos (~1000+ lines). Let me be careful with correctness:

• three@0.160.0 import map, modules: OrbitControls, EffectComposer, RenderPass, UnrealBloomPass, OutputPass.
• InstancedMesh raycast: supported; ensure mesh.instanceMatrix needsUpdate.
• aGlow custom attribute on InstancedBufferAttribute + onBeforeCompile injection. In vertex: attribute float aGlow; varying float vGlow; — with instancing, attributes work per-instance. Inject into 'begin_vertex'? Better inject at '#include ' for declarations both shaders, and set vGlow = aGlow in vertex at begin_vertex; fragment: add emissive after '#include <emissivemap_fragment>': totalEmissiveRadiance += vColor * (uEmissive + vGlow * uGlowGain); — need vColor available: enable instanceColor → defines USE_INSTANCING_COLOR; but vColor only declared if vertexColors or instancing color set at compile time. We set mesh.instanceColor → ok. In fragment, guard with #ifdef USE_INSTANCING_COLOR to avoid compile error when not. Since we always set it, fine either way; still guard.

Careful: onBeforeCompile with InstancedMesh + shadows: fine.

• Shadows: renderer.shadowMap.enabled, type PCFSoft; directional light covering ~40 units; instanced mesh castShadow & receiveShadow; floor receive.

• Bloom params: strength 0.9, radius 0.55, threshold 0.55. ACESFilmicToneMapping, exposure 1.1.

• Fog: scene.fog = FogExp2(0x05060a, 0.016) for depth.

• Floor: CircleGeometry radius 30 with custom canvas grid texture (dark with faint neon rings + radial lines), roughness 0.85, metalness 0.2; plus big soft gradient background via scene.background color + stars? Add subtle star Points sky for atmosphere (cheap, 800 points). And a faint ring glow at floor edge (torus or shader ring) — use a thin ring mesh with emissive basic material for horizon accent.

• Camera default: pos (18, 14, 18) looking at center; OrbitControls damping, maxPolarAngle < π/2 to stay above floor.

• Follow cam: controls disabled? Keep controls enabled but when follow on, each frame lerp controls.target toward wavefront and camera position toward wavefront+offset; user can still rotate via damping conflicts — simpler: follow mode sets target each frame; user rotate still works around moving target. That's actually nice.

Reset animation: run timers: for k-th domino in authored order, at time T_reset = (N-1-k)·0.012s start standing back up: animate θ → 0 over 0.25s (ease). Implement states: state 0 standing, 1 falling (simulated), 2 landed, 3 resetting. During reset, θ = θ_land·(1-ease(t)). Then state 0.

Topple button pushes dominoes[0] (and also any with indegree 0? just index 0 plus maybe give user hint pulse on it).

Edge case: trigger when j already falling/landed → skip. Trigger when θ_i crosses from below: check prevθ < θtrig ≤ θ. Use while sim stepping with dt fixed 1/120 substeps for stability.

Physics step: substep h=1/240 for stiff ODE near topple? g=9.81, h_dom=2: ωmax ~ sqrt(2·3g/(2·(h²+t²))·(h)) ~ sqrt(...)~ up to ~6 rad/s; dt 1/120 fine. Use dt fixed 1/120, 2 substeps per frame at 60fps.

Angular integration: semi-implicit Euler: ω += α dt; θ += ω dt. Add slight damping ω *= (1 - 0.02·dt·60?) small.

Landing: when θ ≥ θ_land = π/2·0.995 (slightly less to avoid z-fight: 1.553): θ=θ_land; if |ω| > 0.8: bounce ω = -ω·0.12, thud + dust + (shake if giant); else ω=0, state=2. Also cap bounces count 2.

Impulse between dominoes: also add tiny forward nudge to i? Not needed.

Chain complete detection: fallenCount === total (or all non... every domino). Then banner+confetti+chord; record time.

Confetti: Points or instanced planes; implement pool 500, each {pos, vel, rot, rotVel, color, life}. Update in CPU, write matrices. MeshBasicMaterial with instanceColor, toneMapped false for pop, side: DoubleSide.

Sparks: THREE.Points with BufferGeometry, attributes pos/vel/life in CPU arrays; additive PointsMaterial size 0.06, vertexColors, transparent. Update per frame; spawn on impact (5) and landing (8 for normal, 60 for giant).

HUD: top-left title; top-right buttons; bottom-left stats panel with counts + falls/sec bar; bottom-center hints; banner center.

Sound toggle default ON but audio starts on first gesture (browser policy) — create ctx lazily on first pointer/button.

Also add keyboard shortcuts.

Resize handler. prefers-reduced-motion? skip.

Also mobile: pointer events for click push; buttons big enough.

Let me also double check three r160 OutputPass exists (yes, examples/jsm/postprocessing/OutputPass.js) and with composer: RenderPass → UnrealBloomPass → OutputPass.

Instanced colors: mesh.setColorAt(i, color) before first render; instanceColor.needsUpdate.

Raycast InstancedMesh: intersection.instanceId ✔.

One more design consideration: course generation must guarantee connectivity — chains dying midway would be embarrassing. Safeguards: after generating ordered points with heading toward next, spacing computed to be 0.55–0.62·(h·0.35)... trigger reach h=2.0 → max gap 1.9; our spacings ~0.6-0.9 ✔. For splits, both children within cone+reach of parent ✔ authored. For safety add post-pass: for each consecutive pair (i, i+1) verify trigger exists; if spacing too large... they'll exist by construction. Also the giant's trigger from ring: authored distance 1.55 with ring domino h=2 ✔ (d_eff=1.55-0.3=1.25, θ_trigger=asin(1.25/2)=0.675 rad ≈ 38.7° ✔ before landing ~89° ✔).

Also, potential double-trigger of giant from multiple ring dominoes: fine (max()).

Giant domino landing: its big face may visually intersect small dominoes — ok.

Quake: push ~10 random standing dominoes with random ω. Fun.

Wind idle sway? No — dominoes should stand still (stability). Tiny glow pulse only.

Let me now also handle: clicking a domino that's standing → push with ω=1.6 in its forward. If user clicks fallen one → nothing (or small spark).

Time to write the file. I'll aim for clean, commented code ~900-1100 lines.

Let me carefully write the ODE constants: I_about_edge = (1/3) m (h² + t²). Torque τ = m g x_cm, x_cm(θ) = -t/2 cosθ + h/2 sinθ (hinge at front-bottom edge; at θ=0, x_cm = -t/2 → restoring; topples when pushed past atan(t/h)≈8°). α = τ/I = (3g (h sinθ - t cosθ)) / (2 (h²+t²)). ✔.

Check terminal ω at θ=π/2: energy: drop of cm height: y_cm(θ) = t/2 sinθ + h/2 cosθ; from θ0=atan(t/h) (balance, ~8°) to π/2: Δy = y(θ0) - y(π/2) = (t/2·sin8° + h/2·cos8°) - t/2 ≈ (0.14·0.5? t=0.28: 0.14·0.139=0.0195 + 1·0.990=0.990) - 0.14 ≈ 0.85. ½ I ω² = m g Δy → ω = sqrt(2 g Δy / ((h²+t²)/3)) = sqrt(2·9.81·0.85/1.36) ≈ sqrt(12.26) ≈ 3.5 rad/s. Trigger transfers: ω_j = 0.62·ω_i·(h_i/h_j)^0.7 + 1.1 → keeps ~3.3 → chain sustains ✔ (needs only to pass 8° balance; ω=3 is plenty; and the +1.1 kick ensures sustain even with losses).

Actually wait — energy transferred physically comes from the falling domino pushing through contact; our simple model just needs to LOOK right, and it will.

Substep: dt=1/120. Damping: ω *= exp(-0.25 dt) tiny.

Spark points: allocate 800.

Let me write files now. First create directory and index.html. Then update the main index page: insert new card after "".

Card:

Description: "Hundreds of neon dominoes topple in accelerating chain reactions across three procedural courses — spiral bloom, serpent waves and a twin-split finale with a giant domino. Custom hinge physics, pentatonic click soundtrack, slow-mo? follow-cam, confetti finale."

Do I include slow-mo? Could add: hold Shift? Keep scope: no slow-mo. Skip mentioning.

Let me write the demo file now. I'll write it in one go, carefully.

Key modules & structure:

Constants: G=9.81, SUB=2 (substeps), DT=1/120.

Domino store: arrays: baseX, baseZ, baseY=0, heading (angle around Y), h, t, w, theta, omega, state, order (authored index), color, isGiant. Triggers: for each i: array of {j, angle}. counts.

Build course returns D array of objects {x,z,heading,h=2,t=0.28,w=0.62,giant=false}.

Course 1 — Spiral Bloom:

• Spiral: φ from 0 to φmax; r(φ)= r_out - c·φ. Choose spacing along arc ≈ 0.66: iterate φ step adaptive: dφ = 0.66 / r. Start r=15 → inward to r=2.6. That yields count ≈ integral r/0.66 dφ... total length ≈ (π/c)(...) whatever — count ~ (area-ish) roughly length/0.66. Length of spiral ≈ ½(rmax·φmax) with r=15, φmax=(15-2.6)/c... pick c so φmax ≈ 5.5·2π? Let me param: turns=5, r from 15 to 2.6: c = (15-2.6)/(2π·5)=0.394. Length ≈ ∫ r dφ = c·φmax²/2 = 0.394·(31.4)²/2 ≈ 194 units → /0.66 ≈ 294 dominoes. Good size.
• Heading: tangent inward = direction of decreasing φ? Chain flows inward: domino k+1 at next inward point; heading_k = atan2(p_{k+1}.z - p_k.z, p_{k+1}.x - p_k.x). Last spiral domino heading toward circle entry.
• Circle ring: center (0,0), ring r=1.55, N=11 dominoes starting at angle α0 = angle of spiral end, going around 2π - step back so last ring domino is adjacent... they all sit on circle, chain: ring k heading toward ring k+1 (tangential chord direction). Last ring domino (k=N-1) heading toward giant at center? Its trigger list will include giant automatically (distance 1.55 < reach 2) — but its forward is tangential, so cone test (angle between fwd and dir-to-giant) = ~90° — OUTSIDE 70° cone! Fix: for last ring domino, set heading toward the giant (radial inward) — visually the domino is rotated to face inward, fine since authored. Then its forward→giant angle 0 ✔. But then the previous ring domino (tangential) must hit IT: direction from ring[N-2] to ring[N-1] is tangential chord ✔ cone ok. Wait also spiral's last domino → first ring domino: spiral end at r=2.6, ring at 1.55, distance ≈ 1.05 (plus lateral) — heading of last spiral domino set toward ring[0] ✔ (I set every domino heading toward next in authored order, so all consecutive triggers have cone angle 0 by construction. Only giant trigger from last ring domino: also consecutive in authored order if giant appended right after ring! Then heading of ring[N-1] = toward giant ✔ automatic.) So rule: EVERY domino's heading = direction to next authored domino; last (giant) heading = outward away from ring (radial), falls onto... floor. And triggers computed geometrically handle splits (non-consecutive pairs within cone). With consecutive-heading construction + spacing ≤ ~1.0, chain connectivity is guaranteed via geometric triggers (cone=0).
• Giant at center: h=4.2, t=0.55, w=1.5. Ring r=1.55: last ring domino h=2 → reach 2 > 1.55 - t_giant/2 (0.275) = 1.275 ✔ θtrig = asin(1.275/2)=39.6° ✔.
• Also giant's own fall: it knocks nothing (nothing within its forward reach: ring dominoes around at 1.55 — giant reach h=4.2!! sinθ=… giant will re-trigger fallen ring dominoes — skipped since not standing. But giant might trigger OTHER ring dominoes still standing? Ring all fell in sequence before giant falls. OK. Giant θ_land: same π/2·0.995. Its face at floor: visual size fine.

Course 2 — Serpent:

• Rows along X from -13 to 13, x-step 0.66 → 40 per row. Rows z: -7..7, rowGap 1.5, → 10 rows → 400 + turns. Turn: semicircle radius 0.75 at each end connecting rows: centers at (±13, z_k+0.75), 4 dominoes on arc each (angles spaced π/4 over π) → arc length 2.36/4 ≈ 0.59 spacing ✔. Alternate left/right ends. Total ≈ 400 + 9·4 ≈ 436. Course 3 — Twin Split:
• Main line from (-14,0) heading +X, step 0.66, 12 dominoes to (-6.1,0). Fork domino F at (-5.4,0) heading +X. Two children: L1 at (-4.9, 0.55) and R1 at (-4.9,-0.55) — both within cone of F? Direction F→L1: angle atan2(0.55,0.5)=47.7° < 70° ✔ distance 0.74 ✔.
• Left arc: semicircle centered C=(1.5,0) radius 7 upper half: angles from 180° to 0° going clockwise (upper): point = C + 7(cos a, sin a), a from π down to 0 → from (-5.5, 0)?? that's near fork. Hmm: arc start should be near L1 (-4.9,0.55). C=(1.5,0), r=7: angle of L1 from C: atan2(0.55, -6.4) ≈ 175°. Arc from 175° → 5° (decreasing, upper semicircle) with spacing 0.66: arc length ≈ 7·(170° in rad=2.967)=20.8 → ~31 dominoes. End point ≈ C+7(cos5°, sin5°)=(8.47, 0.61). Right arc mirrored: end (8.47,-0.61).
• Convergence: two dominoes: EL at (9.1, 0.35) heading toward giant, ER at (9.1,-0.35). Giant at (10.2, 0), h=4.2. EL→giant: dist = sqrt(1.1²+0.35²)=1.154 ✔ reach 2 ✔ cone: heading set toward giant ✔.
• Both EL and ER trigger giant ✔ (both within its incoming range; triggers computed from them to giant geometrically ✔).
• Make it prettier: main line could be two parallel staggered lines? Keep single.

Colors: hue along authored order: HSL(h = 0.02 + 0.85·(i/N) )? rainbow sweep; giant: white-hot. Saturation 0.75, lightness 0.55.

Glow wave: each frame find max order among fallen (wavefront W); glow_i = clamp(1 - |order_i - W|/8,0,1) for standing ones → pulse armed ones ahead of wave. Write into aGlow attribute (needsUpdate). N up to ~700 — fine per frame.

Stats: falls in sliding window (store fallTimes array; count within last 1s).

Camera follow: target smoothed to last fallen pos.

Banner: "CHAIN COMPLETE — 452 DOMINOES IN 9.3S".

Confetti at giant position (or wavefront) burst 450 pieces.

Extra flourish: floor rings shader — I'll generate grid texture via canvas: 1024², dark bg, concentric circles + radial spokes faint cyan/magenta. Plus polar glow. Good.

Stars: Points on dome radius 120, 700 stars, sizes attenuated, additive, subtle.

Sounds:

• ensureAudio() on first gesture.
• click(freq, x): square osc 0.045s + noise hp 1800Hz 0.03s; pan by clamp(x/20).
• thud(size): noise lp 300Hz 0.12s + sine 70→40Hz.
• complete: three-note chord + shimmer.
• topple whoosh? skip.

Pitch ladder: freq_i = 196 · 2^( (degree_i)/12 ), degree_i = round( (i / N) · 24 ) mapped onto pentatonic [0,3,5,7,10] over 2.5 octaves: deg = scale[(i·?) ] — simpler: degree = floor(i * 24 / N) semitone over 2 octaves = pure glissando chromatic — sounds like xylophone run, good. Add tiny random ±30 cents.

Implementation of pushDomino(i, omega0, silent): if state!==0 return; state=1; ω=ω0.

Trigger fire: pushJ with ω_j = max(existing, 0.62·ω_i·pow(h_i/h_j,0.7)+1.05); record fallTime, play click at pan(baseX_j), spawn sparks at midpoint of hinge_i→base_j at height 0.6·h_i·cosθ_i. fallenCount++. If j is giant → bigger click + slight shake.

Landing event: thud(size by h), dust sparks, giant → shake 0.5, confetti if giant is last authored (finale) — actually confetti on chain complete; giant land → shake + thud deep.

Complete check: fallenCount === N → onComplete(): banner text with elapsed = tNow - firstFallTime; confetti at giant; chord. Also auto slow? no.

Reset: state per domino → 3 with resetStart = now + (N-1-order_i)·0.010; during update, if now>resetStart: θ = θ_land·(1 - smoothstep((now-resetStart)/0.22)); when done → state 0, θ=0, ω=0. Reset counters, wavefront=-1, banner hide. Sounds: soft ticks reversed? skip sound during reset (or tiny tick). Add tiny tick per 8th domino.

Quake: choose up to 10 random standing, push with ω 1.2–2.2. Only counts as chain start if none fallen? firstFall handling general: on first push (any source) record startTime.

UI: buttons + kbd shortcuts. Stats panel: FALLEN x/y, SPEED z/s, TIME, bar. Hint bar bottom.

Title: "DOMINO RALLY" with subtitle "chain-reaction playground · demo 054".

Let me also consider performance with 700 instances matrix updates: only update active (falling) + glow each frame; standing static. Reset sets all matrices over ~0.22s window staggered — each frame updates those in reset transition (~200) fine.

Shadow autoUpdate: fine.

Raycast on pointerdown: if clicked domino standing → push ω=1.8 (state 1), spark. Also ignore drags (only if pointer moved < 5px between down/up → treat as click: use pointerdown+up delta check).

Follow camera details: mode 'orbit' | 'follow'. Follow: each frame: if lastFallPos exists: controls.target.lerp(lastFallPos+ (0,0.6,0), 0.06); desired camPos = target + dirOffset where dirOffset = normalized(camPos - target)·dist with dist lerping to 10 and height rising: implement: keep current offset vector, lerp its length to 9.5 and y-ratio. Simpler: spherical around target: slowly rotating azimuth: az += dt·0.15; pos = target + (cos az·9, 5.5, sin az·9); camera.position.lerp(pos, 0.05). Controls.update handles lookAt. Good.

Wavefront for glow & follow: track lastFallen = {x,z,order,time}.

Edge: course building must dispose old InstancedMesh.

MAX_INSTANCES = 900 fixed; courses sized below.

Write code with care around three r160 APIs:

• new UnrealBloomPass(new THREE.Vector2(w,h), strength, radius, threshold)
• renderer.outputColorSpace default SRGB in r160 ✔; toneMapping ACES.
• InstancedMesh.instanceColor: created by setColorAt.
• onBeforeCompile: shader.uniforms.uTime etc.; store ref for updates: mat.userData.shader.

For aGlow attribute updates: geometry.setAttribute('aGlow', new THREE.InstancedBufferAttribute(new Float32Array(MAX),1)); mark needsUpdate on change each frame.

Inject in vertex:

fragment:

Set material.emissive black base? MeshStandardMaterial emissive default black; totalEmissiveRadiance starts as emissive uniform (black). ok.

Roughness 0.35, metalness 0.1, color white (multiplied by instanceColor). Env: add scene.environment? Use RoomEnvironment? Extra import PMREMGenerator + RoomEnvironment gives nicer standard material response: import { RoomEnvironment } from 'three/addons/environments/RoomEnvironment.js'; pmrem. environment intensity subtle. Yes, adds sheen. Cheap one-time.

Floor texture canvas: draw concentric rings + spokes + subtle noise vignette. anisotropy.

OK also banner div + vignette CSS overlay (radial-gradient) for style.

Let me now write the whole HTML file.

Also remember meta description, title.

I'll write it now. Then verify by running a quick syntax check with node (node --check works for ES modules? node --check parses as CommonJS; use node --input-type=module --check? Simplest: node --check fails on import statements... Use node -e "import('...')"? Browser APIs missing. Just do a syntax check via node --input-type=module --check < file? Actually node --check respects extension .mjs. Copy to /tmp/check.mjs and run node --check — import specifiers 'three' won't resolve but --check only parses, doesn't resolve. ✔.

Then update index page.

Now, let me write the code mentally with attention to detail, then emit.

Details on heading: heading angle = atan2(dz, dx); forward vector = (cos, 0, sin). Ry(heading) maps local +Z? Rotation about Y by angle a maps +X to (cos a, 0, -sin a) and +Z to (sin a, 0, cos a). I want local +Z (domino forward) to map to world (cos h, 0, sin h). Ry(θ) maps +Z to (sinθ, 0, cosθ). So need sinθ=cos h, cosθ=sin h → θ = π/2 - h. To avoid confusion, build orientation with quaternion setFromUnitVectors or use Matrix4.lookAt alternative: easier — use headingQuat = new THREE.Quaternion().setFromAxisAngle(Y, Math.atan2(fx, fz)) because Ry(a) maps +Z to (sin a, 0, cos a) → equals (fx,0,fz) when a = atan2(fx, fz). ✔ So headingAngle a = atan2(fx, fz).

Matrix compose: M = T(base)·Ry(a)·T(0,0,t/2)·Rx(θ)·T(0,h/2,-t/2)·S(w,h,t).

Implement with THREE objects:

Per domino per frame:

✔.

Hinge world pos H_i = base + fwd·(t/2): fwd=(sin a,0,cos a).

Trigger precompute O(N²)=900²=810k ops once per course — fine.

Trigger condition parameters: cone cos70°=0.34 → accept dotNorm > 0.34 (i.e., <70°). d_eff = dot((base_j - H_i), fwd_i) - t_j/2 - 0.02; require d_eff < h_i·0.98 (reachable) and d_eff > -0.1; lateral = |cross| < 0.42 + w_j/2 + w_i/2... let me: lat = |dot(delta, side_i)|; accept lat < (w_i/2 + w_j/2 + 0.18). θtrig = asin(clamp(d_eff / h_i, 0.02, 0.99)). Also require vertical: base_j.y (0) vs tip height: fine (flat floor).

Also contact height for spark: h_contact = h_i·cosθtrig clamp 0.2..h_i.

Store triggers[i] = [{j, ang, ch}].

Sim per substep for each active i:

prevθ tracking per substep.

Fire trig(j): if state[j]!==0 → skip; state[j]=1; ω[j]=max(ω[j], 0.62ω_iMath.pow(h_i/h_j,0.7)+1.05); fallenOrder push; sounds; sparks; count++; if j giant: shake+=0.15.

Note: when giant falls onto floor, its triggers may fire on already-fallen → skipped ✔.

fallTimes push now for speed calc.

firstFallTime set on first successful push (including click/quake/topple).

completeCheck in frame loop.

Sparks pool: Float arrays pos(3), vel(3), life, maxLife, color(3). Points geometry dynamic. spawn(x,y,z,n,spread,speed,col): fill dead slots. Update: vel.y -= 9.8dt0.6; pos+=vel*dt; life-=dt; write positions; alpha via... PointsMaterial no per-point alpha; fade by shrinking? Use size attenuation and set color→black (additive blending → black = invisible ✔). So color *= lifeFrac.

Confetti instanced planes: pool 500: {pos, vel, rotAxis?, rot euler angles, spin, life, maxLife 3.2, scale, color}. Update matrices for alive; material MeshBasicMaterial({side:DoubleSide, vertexColors? use instanceColor, transparent, opacity:0.95, toneMapped:false}). Hide dead by scale 0.

Camera shake: shakeAmp decays exp; offset = (rand-0.5)*amp applied to camera position after controls.update (add to camera.position directly each frame, not accumulating: controls recompute? OrbitControls sets camera pos from spherical each update only when damping changes... adding offset after update is fine (temporary).

Audio:

Master volume toggle soundOn → master.gain.

UI events: buttons + keydown (Space preventDefault scroll).

Elapsed time display: from firstFall to complete or now while running.

fall speed: count fallTimes within last 1.0s (prune).

Now, course 2 serpent detail: rows z from -7.5 to 7.5 step 1.5 → 11 rows. Row dir alternates. Row k (dir=+1): x from -13 to 13 step 0.66 (40 dominoes). Turn at x=13: semicircle center (13, z_k + 0.75) radius 0.75 from angle -90°?? Let me param: end of row k at (13, z_k) heading +X. Next row k+1 at z_{k+1}=z_k+1.5 traversed heading -X starting at (13, z_{k+1}). Arc: center C=(13, z_k+0.75), r=0.75. Points: angle from -π/2 (point (13, z_k)) to +π/2 (point (13, z_{k+1})) going counterclockwise?? Points on arc: P(φ)=C + r(cosφ, sinφ). φ=-π/2 → (13, z_k+0.75-0.75)=(13, z_k) ✔. φ=+π/2 → (13, z_{k+1}) ✔. Going through φ=0 → (13.75, z_k+0.75) — arc bulges outward +X ✔. Place 4 intermediate dominoes at φ=-π/2 + k·(π/2)/... spacing: arc length π·0.75=2.36; with 4 dominoes: gap 0.59 ✔ at φ = -π/2 + m·π/ (4) ... m=1..4? m=1: φ=-π/4 → (13.53, z+0.22); m=2: φ=0 → (13.75, z+0.75); m=3: φ=π/4; m=4: φ=π/2 → that's the row start point — skip m=4 (row k+1's first domino is there... row start x from -13..13 — conflict! Row points go from -13 to 13; the arc connects row END (13, z_k) to row START (13, z_{k+1}) — but row k+1 traversed in -X direction starts at x=13. So arc's φ=π/2 point = (13, z_{k+1}) = first point of row k+1 — don't duplicate: arc adds m=1,2,3 only, then row k+1 points from x=13 down to -13. And left turns: row k+1 ends at (-13, z_{k+1}), turn center (-13, z+0.75) bulge -X, φ from -π/2... P(φ)=C+r(cosφ,sinφ): start (-13, z_{k+1}): φ: cosφ=0, sinφ=-1 → -π/2 ✔; going through φ=π → (-13.75, ...) bulge -X; end φ=π/2... from -π/2 decreasing? Go φ from -π/2 to -3π/2?? Simplest: φ from π+π/2... let me just use φ ∈ {-π/2, -π/2 - π/4·...} hmm. Use param s∈(0..1): for right turn (bulge +X): φ(s) = -π/2 + s·π. For left turn (bulge -X): φ(s) = -π/2 - s·π (goes through -π: cos=-1 → x=Cx-0.75 ✔ bulge -X). End: φ=-3π/2 ≡ π/2 ✔ (13→ -13 case: C + r(cos(-3π/2), sin(-3π/2)) = C + (0, +0.75) ✔). So left turn intermediate: s=1/4,2/4,3/4 → 3 dominoes. Same formula with sign.

Headings: all set toward next point ✔ automatic.

Count: 11 rows·40 + 10 turns·3 = 470. ✔ <900.

Course 3 counts: 12 + 1 + 2·(31) + 2 + 1 ≈ 78 — small; make radius 9 and line longer: line from -15 → -7 (0.66 step, 13), fork, arcs r=9: length π·9≈28 → 43 each; total ≈ 13+1+86+2+1 ≈ 103. Add inner decorative? Or increase domino size? Keep as "Twin Split" — smaller but elegant. Could add second parallel main line (double track) to beef visuals: two lines z=±0.4 from -15 to -7, each ends with own fork domino, four arcs?? Overcomplicate. Instead make arcs double: two concentric arcs per side (r=9 and r=7.6)? Each arc separate chain: fork hits L1(r9 start) — who hits r7.6 start? Add fork2... complexity risk. Alternative: after split arcs converge, add a straight "victory lap" line back across center to a second giant? Keep single giant finale. 103 dominoes is fine — spacing visuals clean. Maybe bump main line count: from x=-15 to -6 step 0.62 → 15 dominoes. Total ~110. OK.

Actually let me enrich course 3: after the two arcs converge at EL/ER (9.1,±0.35), giant at (10.4,0), and BEHIND the giant add a radial sunburst: 12 spokes of 3 dominoes each starting at r=1.2 from giant... giant falls forward (+X) though, only triggers things in front. Instead: the giant falls onto a "star pad": in front of giant place a fan of 5 lines radiating (±60°) each 5 dominoes long (spacing 0.66): giant reach 4.2 → easily triggers all 5 line-starts (cone covers ±70°; authored headings radiate). Giant falling knocks 5 lines → they race outward ✔ spectacular finale. Lines start at distance 1.6 from giant base along their headings... wait giant falls toward +X; lines placed in front cone. First domino of each line at dist ~1.7 from giant base: giant tip sweep radius 4.2: θtrig = asin((1.7-0.28)/4.2)=19.8° ✔. Each line: 6 dominoes heading outward, headings toward next ✔. Fan angles: -50°,-25°,0°,25°,50°. Adds 30. Total ≈ 140.

Similarly course 1: giant at center falls outward (heading = away from ring entry): add fan of 5 short lines in front of giant too? Giant at center surrounded by ring at 1.55 all around — fan lines would start inside ring... skip for course 1; giant falls onto fallen ring — fine visually, big thud + confetti at complete.

Hmm wait course 1: giant's heading: authored last; set heading = radial direction at entry angle (pointing away from ring center? it's AT center). Set heading toward angle of last ring domino + π? It should fall AWAY from the incoming ring domino to look natural (pushed from behind): the ring domino at angle φ_L hits giant → giant falls in direction from ring domino toward giant continued: dir = normalize(giant - ringPos) = radially inward = -radial at φ_L → giant falls toward center-opposite... it's at center so falls to the opposite side of the ring ✔ natural.

Course 3 giant: pushed from behind by EL/ER (which are at x<giant), falls +X toward fan ✔.

Now camera default per course: fit radius ~ course extent: course1 r≈15 → cam (16,15,16); course2 extents 14×8 → cam (15,13,15); course3 → (16,13,10)... just use same default; fine.

Floor radius 34 covers extents (course1 15.75 max, course3 fan up to 10.4+1.7+5·0.66≈15.4 ✔).

Colors per course type: spiral: hue sweep by radius/order; serpent: row-based hue bands (order works); split: two branches different hues (left warm, right cool) — order-based sweep ok too. Keep order-based sweep for all; giant white.

Also idle "ready pulse": uEmissive base 0.22 + global subtle pulse 0.05·sin(t·2) — via uEmissive uniform update when shader ready.

aGlow update per frame: compute wavefront order W = max fallen order; for standing i: g = clamp(1 - (order_i - W - 1)/6, 0, 1) if order_i > W else small for behind? Only ahead: if order_i>W: g=clamp(1-(order_i-W-1)/6,0,1)² else 0. Write array, needsUpdate. O(N) fine.

For splits, order is linear so glow approximates — fine.

Reset also zeroes aGlow.

Now — write it. Also include maybe not needed.

One more check: UnrealBloomPass with emissive vColor — values: vColor lightness 0.55 * uEmissive 0.22 ≈ 0.12 luminance — below threshold 0.55 → no bloom normally; glow boost uGlowGain 1.6 → vGlow 1 → emissive ≈ 0.55·(0.22+1.6)=1.0 → blooms on armed wavefront ✔. Giant white vColor 1 → base 0.22 fine, when armed glows hot ✔. Confetti toneMapped false basic colors 1.0 → blooms lightly ✔.

Floor emissive none; grid texture subtle.

Alright — also stats: TIME shows elapsed since first fall while running; SPEED falls/s.

Edge: TOPPLE pressed twice — pushDomino guards state.

Quake fun.

Also add small "push hint": first domino glows pulsing at start (aGlow[0]=pulse until first fall). Implement: if fallenCount==0: aGlow[0] = 0.5+0.5 sin(t·4).

pointer raycast: use e.clientX/Y → NDC; ray.intersectObject(inst); instanceId.

OK writing the file now. Also the demo index card + main index update.

Let me also double check OutputPass import path: 'three/addons/postprocessing/OutputPass.js' ✔ r160.

RoomEnvironment import: 'three/addons/environments/RoomEnvironment.js' ✔. Usage:

r160: RoomEnvironment() no renderer arg ✔.

Now writing. I'll produce the full file in one write. Careful with template literals inside the HTML (fine) and avoiding </script> sequences inside JS strings (avoid). Shader strings with #include fine.

Let me draft the full code.

Panels (consistent with prior style):

• #panel-title top-left: h1 DOMINO RALLY, sub: CHAIN-REACTION PLAYGROUND · DEMO 054
• #panel-ctrl top-right buttons: TOPPLE / RESET / COURSE / CAMERA / SOUND / QUAKE
• #panel-stats bottom-left: FALLEN x/y bar, SPEED, TIME
• #panel-course bottom-right?: course name label. Put under ctrl? bottom-left into stats; course name in stats panel row.
• #panel-bottom center hints.
• #banner center.
• vignette overlay div.

Now JS full. Let me write carefully.

Lights:

Point light intensity in r160 physical units — 220 with distance 60 decay 2: at 15 units → 220/225 ≈ 1 ✔.

Floor:

Also horizon ring: TorusGeometry(33.6, 0.06) rotated flat, MeshBasicMaterial(0x1de2ff, toneMapped false, transparent, opacity 0.5). Wait bloom threshold: 0.5 alpha cyan → mild bloom nice.

Stars: 800 points on upper hemisphere radius 140-200, PointsMaterial size 1.6 sizeAttenuation false? attenuation true size 0.9, additive, opacity 0.7, color 0xaac4ff. Positions random sphere y>0.

Domino instanced mesh:

Hmm: InstancedBufferAttribute on regular BufferGeometry used by InstancedMesh — yes, instanced attributes work.

instanceColor: set via setColorAt at build.

Domino data arrays (per course):

state: 0 standing,1 falling,2 landed,3 resetting.

buildCourse(idx):

Colors: color = new THREE.Color().setHSL((0.02 + 0.85 * i/(N-1))%1, 0.75, 0.56); giant: (1,1,1)· maybe slight warm: setHSL(0.08,0.4,0.9).

Matrix helper:

heading = atan2(fx, fz) where fwd=(fx,fz)... earlier: heading a = atan2(fx, fz) with fwd=(sin a, cos a) ✔.

Course generators return array of {x,z,giant?}. Headings assigned after: for i<N-1: heading toward next; last: keep specified fallHeading.

genSpiral():

Now write the full demo file. This is a big file; I'll write it in parts using the write tool (full rewrite is fine for a new file). Let me compose the entire HTML carefully.

Now let me review some potential issues in the code:

1. Twin Split course chain order problem: I append fork → left arc (31 dominoes) → right arc → gate dominoes → giant → fan. The problem: after the left arc ENDS (at angle 0.06, near (10.7, 0.5)), the next authored domino is the right arc START (at angle -175°, near (-2.8, -0.5)). The heading of the last left-arc domino points backward across the map — but geometric triggers: the left arc end domino won't trigger the right arc start (too far). Chain dies!

The fork domino triggers BOTH first arc dominoes geometrically (both within cone/reach): fork at (-5.5, 0) heading +X. Left arc start: at angle a0 = atan2(0.55, -5.0-2.2) = atan2(0.55, -7.2) ≈ 175.6° → point = C + R(cos, sin) = (2.2 + 8.6·cos(175.6°), 8.6·sin(175.6°)) = (2.2 - 8.577, 0.665) = (-6.377, 0.665). Distance from fork (-5.5,0): Δ=(-0.877, 0.665), dist=1.10. fwd = dot with (1,0) → -0.877 → fwd/dist = -0.797 < CONE(0.342) → NOT triggered! The left arc start is BEHIND the fork domino. The chain breaks immediately!

I designed this wrong: the arc start point is at x=-6.38 which is BEHIND the fork at -5.5. The fork heading +X can't reach it. Also, children L1/R1 should be right in front of the fork. Let me redesign:

• Main line along +X to fork F at (-5.5, 0).
• L1 at (-4.9, 0.6), R1 at (-4.9, -0.6): dist from F = sqrt(0.6²+0.6²)=0.849; fwd = 0.6; fwd/dist = 0.707 > CONE ✔ lat = 0.6; lat limit = w/2+w/2+0.2 = 0.31+0.31+0.2=0.82 ✔. dEff = 0.6-0.14-0.02=0.44; θtrig=asin(0.44/2)=12.7° ✔.
• L1's heading should point toward the arc's next point. The arcs: circle center C=(2.2, 0), R=8.6. But L1 at (-4.9, 0.6) — distance from C: sqrt(7.1²+0.6²)=7.13 ≠ 8.6. The arc would start discontinuously. Better: pick arc circle passing near L1: Let me place C at (1.5, 0), R = 6.6. Then leftmost point of circle = (1.5-6.6, 0) = (-5.1, 0). Hmm that overlaps the fork at (-5.5,0) and L1 (-4.9,0.6)...

Let me parametrize: I want L1 ≈ at circle angle ~172° (upper) so the arc sweeps up and around. Circle: C=(1.5,0), R=6.6: point at angle 172°: (1.5+6.6cos172°, 6.6sin172°) = (1.5-6.537, 0.918) = (-5.037, 0.918). L1 should be there. So place L1 = circle point at angle aStart, R1 = circle point at angle -aStart, with aStart = 172°. Fork F at (-5.5, 0). F→L1: Δ=(0.463, 0.918), dist=1.028, fwd=0.463, fwd/dist=0.45 > 0.342 ✔ lat=0.918 > 0.82 ✗! Too much lateral. Hmm.

Move fork closer to the split: F at (-5.2, 0)? Main line step 0.62 from -15: -15+k·0.62: k=15 → -5.7; k=16 → -5.08. Let me instead place fork at fixed position and line ends at it: simpler — generate main line with exact positions ending at fork x.

Alternative cleaner design: make the fork symmetric with the circle: place F at (-4.6, 0) — inside the circle (circle leftmost -5.1). Then F→L1(-5.037, 0.918): Δ=(-0.437,0.918) fwd<0 ✗. No — L1 is behind-left again. The issue: circle leftmost point is at the fork's x; arc starts go backward.

Better geometry: make the split before the circle: two children veer at ±45°, and the arcs are on circles whose start angle matches the veer. E.g., upper arc: circle center at (0, R_off)... Let me think of a Y: main line +X; at F, two branches at ±40° for a couple dominoes, then each curves into a semicircle and returns.

Simplest robust approach: parametrize each branch as a smooth curve: start at F, initial direction ±40°, then bend toward parallel ±z lanes, big arc, and converge. That's a lot of math. Alternative: make each branch a circular arc with center on the z-axis perpendicular at F: upper branch: circle center (F.x, +Rc), radius Rc, arc from angle -90° (point F) sweeping... point = C + Rc(cosφ, sinφ). Start at F: φ=-π/2 gives (F.x, Rc - Rc)= (F.x, 0) ✔... wait C=(F.x, Rc), point=C+Rc(cosφ,sinφ); φ=-π/2 → (F.x, 0) = F ✔. Going φ from -π/2 to +π/2: point at 0 → (F.x+Rc, Rc); at π/2 → (F.x+... cos90=0 → (F.x, 2Rc). Hmm that curves left/up around. Direction of travel at start: tangent = d/dφ = Rc(-sinφ, cosφ) → at -π/2: (Rc, 0) → +X ✔. At φ=0: tangent (0, Rc) → +Z. At φ=π/2: tangent (-Rc, 0) → -X. So upper branch curls up and comes back. That makes a loop, not what I want.

Let me use a different well-trodden shape: two semicircle arcs forming a circle around a center: F at left side of an imaginary circle of radius R centered O; branches travel along the circle clockwise (lower) and counterclockwise (upper), meeting at the right side. Circle center O = F + (R, 0). Upper branch: points O + R(cos α, sin α) for α from 180° down to 0°. At α=180°: (O.x - R, 0) = F ✔. Tangent direction for decreasing α: d/dα reversed: -(−R sin α, R cos α) = (R sin α, −R cos α); at α=180°: (0, R) → +Z?? That's upward (+Z). Hmm: with sin180=0, -cos180=1 → (0, R) yes +Z. Upper branch should initially go +X-ish... at the leftmost point of a circle, tangent is ±Z indeed. So the branch leaves F perpendicular to the main line. The trigger cone from F (heading +X) to first upper domino: direction F→U1. U1 at α=170°: O+R(cos170°, sin170°) = F + (R + Rcos170°, R sin170°) = F + (R(1-0.985), R·0.174) = F + (0.015R, 0.174R). With R=7: Δ=(0.105, 1.216), dist 1.22; fwd = 0.105 → fwd/dist = 0.086 < 0.342 ✗. Cone fails again — the arc bends away too sharply.

Fix: give the split a few straight veer dominoes first. Branch start: F → V1 at F + 0.62·(cos40°, sin40°) = F+(0.475, 0.398). F→V1: fwd=0.475, dist=0.62, fwd/dist=0.766 ✔ lat=0.398<0.82 ✔. V1 heading toward V2 = V1 + 0.62·(cos40°,sin40°)... then blend into the circle. To keep it simple and guaranteed: generate each branch as an arc of a circle whose tangent at the branch start matches the veer direction. Circle with tangent dir (cos40°, sin40°) at point V2: center = V2 + R·(−sin40°? ...). For counterclockwise travel, center is 90° left of tangent: left of dir (cos40°,sin40°) is (-sin40°, cos40°). Center_up = V2 + R·(-sin40°, cos40°). Then arc points with decreasing... this is getting heavy but it's just math I can write carefully:

Parametrize arc by arc-length: point(φ) = C + R(cosφ, sinφ). Tangent for increasing φ is (-sinφ, cosφ). Want tangent at start = dir (cos40°, sin40°): need (-sinφ0, cosφ0) = (cos40°, sin40°) → φ0 = 90°+40° = 130°. So C_up = V2 - R(cos130°, sin130°) = V2 - R(-0.643, 0.766). With R=7.5, V2 = F + 2·0.62·(cos40°, sin40°).

Where should the arc END? At the right side where both arcs converge at gate near giant. Upper arc: sweep φ from 130° upward? If we increase φ, we go counterclockwise around C_up: positions move... at φ0=130° point is V2 ✔. Increase φ to 130°+Δ: moves with tangent rotating counterclockwise — the branch curls left (up and over). We want it to sweep up and around to the right side, ending heading +X again? Symmetric target: end point E_up = (Ex, +0.35) with tangent +X: tangent +X means (-sinφ1, cosφ1) = (1, 0) → φ1 = 270°... wait (-sin270°, cos270°) = (1, 0) ✔ φ1=270°. Sweep from 130° to 270° = 140° of arc. Point at 270°: C_up + R(cos270°, sin270°) = C_up + (0, -R) = (C_up.x, C_up.y - 7.5). C_up = V2 - R(-0.643, 0.766) = V2 + (4.82, -5.745). V2 = F + (0.95, 0.796) where F=(-6.2? let me set F=(-6.5,0)) → V2 = (-5.55, 0.796). C_up = (-0.73, -4.95). End point = (-0.73, -12.45)?? That's way below — wrong: the circle center is below the start, so the arc dips first... no wait — tangent at start is +40° (up-right), center to the LEFT of travel (up-left): center = V2 + R·(left normal). Left of (cos40°, sin40°) = (-sin40°, cos40°) = (-0.643, 0.766). C_up = V2 + R·(-0.643, 0.766) = (-5.55-4.82, 0.796+5.745) = (-10.37, 6.54). Hmm I had the sign flipped. Let me redo: C = point - R·(tangent rotated?) For a circle traversed counterclockwise, center = point + R·n where n = left normal of tangent = (-ty, tx)... For CCW: tangent = (-sinφ, cosφ), normal (point→center) = (cosφ, sinφ). Check: point - center = R(cosφ,sinφ) → center = point - R(cosφ,sinφ). With φ0=130°: (cos130°, sin130°)=(-0.643, 0.766). C_up = V2 - 7.5·(-0.643, 0.766) = V2 + (4.82, -5.745) = (-0.73, -4.95). The center is down-right of V2, meaning the circle curves... tangent (cos40°, sin40°) with center down-right → rotation is clockwise when viewed... travel direction along increasing φ is CCW; but is our motion increasing or decreasing φ? At φ0=130°, derivative w.r.t. φ = R(-sinφ, cosφ) = R(-0.766, -0.643) → pointing down-left — NOT our desired direction (cos40°, sin40°)=(0.766, 0.643). So motion is with DECREASING φ. As φ decreases from 130°, tangent = -d/dφ direction = (0.766, 0.643) ✔ initially up-right. Continue decreasing φ: at φ=90°: point = C + R(0,1) = (-0.73, 2.55); tangent (with decreasing φ) = (sinφ, -cosφ) = (1, 0) → +X. At φ=0°: point = C+(7.5, 0) = (6.77, -4.95); tangent = (0, -1) → -Z. Hmm the arc goes up over the top and comes down on the right side heading -Z at φ=0. I want it to end at gate near (9, 0.35) heading +X-ish toward giant. Continue to φ=-90°: point = C + (0, -7.5) = (-0.73, -12.45) — no good; the arc is circling back down.

This circle geometry gives a loop-de-loop; what I actually want is simpler: two big mirrored S-curves or simply two arcs of a LARGE circle centered near the fork, subtending from ~±15° to ±...

You know what — simplest bulletproof approach: define each branch as a polyline path via a few control waypoints and sample it with even spacing, computing heading toward next sample. Chain connectivity is automatic (heading→next, spacing 0.66). The trigger cone test then always passes for consecutive ones. The only tricky spots are: (a) fork → two branch heads (one F domino triggers two children: both children within cone ±40°, spacing 0.7 — with CONE=cos70°=0.342, ±40° is fine ✔); (b) branch tails → gate dominoes (consecutive in authored order per branch ✔ if I author branch A fully, then gate A... but authored order is linear: main→fork→branchA(complete)→gateA→? then branchB? BranchB start is back at the fork — gateA's heading would point back to branchB start, wrong direction but it doesn't matter: gateA needs to trigger the GIANT geometrically, not branchB. The giant gets triggers from BOTH gateA and gateB geometrically (both within reach of giant, heading toward giant). Authored order only sets headings; triggers are geometric. So:

Order: [main line..., F, veerA1, veerA2, arcA..., gateA, giant?, ...] — no wait giant must come after both gates for heading of gateA to point to giant... Let me order: main..., F, [branchA: veerA1, veerA2, arcA pts..., gateA], [branchB: veerB1, veerB2, arcB pts..., gateB], giant, [fan...].

• F's heading → veerA1 (fine, triggers veerB1 geometrically too since veerB1 is in F's cone mirror side ✔ as long as both within cone: headings ±40° vs cone 70° ✔).
• branchA chain: consecutive ✔, ends at gateA; gateA's heading → veerB1 (authored next!) — points backward across map. BAD: gateA would visually be rotated facing away from the giant, and its geometric trigger onto the giant requires the giant in gateA's forward cone — fails. FIX: after generating, override headings: gateA.heading = atan2(giant.x - gateA.x, giant.z - gateA.z); same for gateB. Then both gates face the giant ✔ triggers geometric ✔ (giant near face: dist ~1.1 < h=2 ✔). And veerB1's heading: authored next is veerB2 ✔ (since branchB entries are consecutive). gateA's backward heading no longer matters because we override. Also the last arcA point → gateA ✔ consecutive.

Also fan: fan lines after giant; each fan domino's heading along its radial direction — my existing code handles fan headings with the override loop (checking if next fan domino is >1.2 away → re-point radially). But wait: fan lines: for angle fa, k=0..5 along radial dir — consecutive k's ARE along the same line with spacing 0.66 ✔ so authored heading works within a line; the issue is only at line boundaries (last of line m → first of line m+1): heading would point sideways to another line's start — harmless visually? A fan domino at line end rotated toward the next line's start looks odd (its forward faces sideways) but it falls... it has nothing to hit — it's the END of its line. Its heading only affects its own fall direction and what IT can trigger (nothing behind it). Falling sideways looks wrong though. My override loop: if (list[i].fan && list[i+1] && list[i+1].fan) { if dist>1.2 → repoint radially }. At line boundary, dist between last-of-line-m and first-of-line-m+1: first of next line is at radius 1.9 from giant at different angle; last of line m at radius 1.9+5·0.66=5.2. Distance > 1.2 ✔ → repoint ✔. But the repoint formula uses Math.atan2(list[i].x - gx, list[i].z) — atan2 args: my heading convention is heading = atan2(fx, fz) where fwd = (sin h, cos h). Radial dir = normalize((x-gx, z-0)) → fx ∝ (x-gx), fz ∝ z → heading = atan2(x-gx, z) ✔ matches.

Also the giant's heading: fallHeading π/2 → fwd = (sin(π/2), cos(π/2)) = (1, 0) = +X ✔ toward the fan ✔. Giant triggers fan-line starts geometrically: giant h=4.4, reach 4.4; fan starts at radius 1.9 from giant base: hinge at gx + t/2=0.275 → dist ≈ 1.9-0.275=1.63; dEff = 1.63 - 0.14 - 0.02 = 1.47 < 4.31 ✔ θtrig=asin(1.47/4.4)=19.5° ✔. Cone: fan angles ±0.85 rad = ±48.7° < 70° ✔. lateral: fan start at z=±1.9·sin(0.85)=±1.43, x=1.9·cos0.85=1.25; giant w=1.5 → lat limit = 0.75+0.31+0.2=1.26 < 1.43 ✗!! The outermost fan lines (±0.85) are outside lateral tolerance at their START. Hmm. Lateral check uses |lat| < w_i/2 + w_j/2 + 0.2. For giant (w=1.5): 0.75+0.31+0.2 = 1.26. Fan start lat 1.43 → rejected. The outer fan lines won't be triggered by the giant directly... but their inner neighbors? Fan lines don't chain sideways (they diverge). Line at ±0.42: lat = 1.9·sin(0.42)=0.775 ✔ triggered. Lines ±0.85 orphaned. Fix: widen lateral slack to +0.45 → 1.51 ✔. Or reduce fan spread to ±0.7: lat=1.9·sin0.7=1.22 ✔ <1.26 barely. I'll do both: fan angles ±0.72 max and lateral slack 0.45. Actually careful: increasing lateral slack may cause accidental triggers in dense spiral course (neighboring spiral arms!). Spiral arm spacing: consecutive turns differ in radius by c·2π = 0.394·6.283 = 2.48. A falling spiral domino's side reach: lateral up to 0.31+0.31+0.45=1.07 < 2.48 ✔ safe. Serpent row spacing 1.5: lateral neighbor rows at 1.5 > 1.07 ✔ safe (side vector check). But cone check: fwd/dist > 0.342 needed — rows ahead/behind: a domino's NEXT row is behind it (reverse direction) → fwd negative → rejected ✔. Turns: fine.

For the giant in spiral course (w=1.5): ring dominoes at 1.62 around center; last ring domino heading toward giant (authored ✔ consecutive). Triggers: dEff = 1.62 - 0.275(giant t/2) - 0.02 = 1.325 < 1.96 ✔.

And ring dominoes triggering EACH OTHER: consecutive ✔ chord spacing = 2·1.62·sin(π·/11)= 2·1.62·sin(16.36°)=0.912 ✔ within reach 2.

Wait, one more spiral issue: the spiral ENDS at rIn=2.7 and ring is at 1.62. Last spiral domino at r≈2.7, first ring domino at 1.62 at angle endA + step. endA = atan2(-(rIn) sin(phiMax), rIn cos(phiMax)) — the spiral point at phiMax: x = rIn·cos(phiMax), z = -rIn·sin(phiMax) → its angle in (x,z) plane: atan2(z, x) = -phiMax. So endA should be -phiMax. My code: endA = Math.atan2(-rIn·sin(phiMax), rIn·cos(phiMax)) = atan2(-sin, cos) = -phiMax ✔ good. Distance from last spiral point (r=2.7 at angle -phiMax) to first ring point (r=1.62 at angle endA + (2π-0.55)/11): Δangle = 0.512 rad. Positions: P1=2.7·(cos, sin), P2=1.62·(cos(a+0.512), sin(a+0.512)). Distance: sqrt(2.7²+1.62² - 2·2.7·1.62·cos(0.512)) = sqrt(7.29+2.62-8.748·0.871)= sqrt(9.91-7.62)= sqrt(2.29)=1.51. Hmm — spacing 1.51 > typical 0.66 but trigger reach is h=2: dEff = 1.51·cos? The heading of last spiral domino points toward ring[0] (authored ✔ cone=0). dEff = dist(1.51) - t/2(0.14) - 0.02 = 1.35 < 1.96 ✔ θtrig = asin(1.35/2)=42.4° ✔ works. But visually a 1.51 gap means the falling domino's tip barely bridges — looks OK since it sweeps through.

Hmm wait, actually there's a subtlety: hinge is at front edge: H = base + fwd·t/2; dist measured from H to next base. Since heading points at next base, H is 0.14 closer → effective gap 1.37. Fine.

Also ring placement: ring spans (2π-0.55) over 11 dominoes starting at endA+step — the 0.55 gap leaves an opening; doesn't matter.

Now check spiral start: first domino at r=15.2. Floor radius 34 ✔.

Course extents for camera: fine.

2. genTwinSplit rewrite: Let me rewrite it cleanly:

Simplest: quadratic/cubic Bezier per branch! P0=V2, P3=gate, control points: P1 = V2 + dir0·L1 (continue the veer), P2 = gate + (-1, side·?)·... gate tangent should point toward giant: gate dir = normalize(giant - gate). P2 = gate - gateDir·L2. Cubic bezier B(t). Sample at ~0.66 spacing: sample finely (t step 0.02), walk accumulating arc length, emit point every 0.66. Headings auto (toward next). This is robust and smooth. Let me define:

side=+1 (upper, z>0): gate at (giant.x - 1.05, +0.33)? For symmetry gates at (8.6, ±0.5). Control arms: L1 = 3.2, L2 = 3.2. B(t) for side +1: P0=V2=(-6.32+1.24·cos38°, 1.24·sin38°)=(-6.32+0.977, 0.763)=(-5.34, 0.763). P1 = P0 + dir0·3.2 = (-5.34+2.52, 0.763+1.97)=(-2.82, 2.73). P3 = gate (8.6, 0.5). gateDir = normalize(giant-gate) = normalize((1.2, -0.5)) = (0.923, -0.385). P2 = P3 - gateDir·3.2 = (8.6-2.95, 0.5+1.23)=(5.65, 1.73). The curve: from (-5.34,0.76) up-right to (-2.82,2.73) ctrl, to (5.65,1.73) ctrl, to (8.6,0.5). Max z around t=0.5: B(0.5)= (P0+3P1+3P2+P3)/8 = ((-5.34+3·-2.82+3·5.65+8.6)/8, (0.763+3·2.73+3·1.73+0.5)/8) = ((-5.34-8.46+16.95+8.6)/8, (0.763+8.19+5.19+0.5)/8) = (11.75/8=1.47, 14.64/8=1.83). Hmm z max ~1.83 — the branches bulge only ±1.9 from center. I want a BIG dramatic split. Increase L1/L2 and push control points outward: make P1 = P0 + dir0·4.5 + sidePush? Better: choose P1 = (-2.5, side·5.5), P2 = (5.0, side·4.2) explicitly for visual control rather than tangent-derived. Tangent at start won't exactly match veer dir, but consecutive-heading construction makes the chain work regardless; a slight kink at V2 is invisible once headings auto-align. Actually headings auto-align means the domino at V2 faces B(0+ε) — the veer dominoes just flow into the curve. The fork F's cone check onto V1 (±38° < 70°) ✔.

Let me directly design curves: side +: P0=V2 (-5.34,0.76) hmm let me simplify: skip separate veer points; P0 = F + dir0·0.66 (one veer point)... Actually keep TWO veer points for a clean fork look: V1 (0.62), V2 (1.24). Then bezier P0=V2, P1=(-2.6, side·5.6), P2=(5.2, side·4.4), P3=gate(8.55, side·0.45). B(0.5): ((-5.34-7.8+15.6+8.55)/8, (0.76+16.8+13.2+0.45)/8) = (11.01/8=1.38, 31.2/8=3.9). z max ≈ 3.9 ✔ nice spread. Curve length estimate: rough chord sum: V2→P1: (2.74, 4.84)=5.56; P1→P2: (7.8,-1.2)=7.89; P2→P3: (3.35,-3.95)=5.18 → ~14-15 units → ~22 dominoes per branch.

Gates at (8.55, ±0.45); giant at (9.8, 0): dist = sqrt(1.25² + 0.45²) = 1.33 < 2 reach of gate domino (h=2): dEff = 1.33 - 0.275 - 0.02 = 1.03 ✔. Cone: gate heading overridden toward giant ✔ (cone 0).

Fan: from giant (9.8, 0): starts at radius 1.9 → x from 9.8+1.9·cos(fa)... fan angles ±0.72, ±0.36, 0: outermost lat = 1.9·sin(0.72)=1.25 < lat limit 0.75+0.31+0.45=1.51 ✔. Fan line length 6 → ends at 1.9+5·0.66=5.2 → x max 9.8+5.2=15 ✔ within floor.

Total twin-split count: 15 + 2 + 2·(22+2... let me count: veer 2 per branch + ~22 bezier + 1 gate = ~25 per branch → 15+2·25+1+30 = ~96. Fine.

Also authored order: [main(14 pts) + F, V1a, V2a, bezierA..., gateA, V1b, V2b, bezierB..., gateB, giant, fan...]. Headings: F→V1a ✔ (cone to V1b geometric ✔). gateA's authored next = V1b — heading override needed for gateA → giant. I'll mark gates with flag gate:true and after finalizeHeadings, override: gate.heading = atan2(giant.x - gate.x, giant.z - gate.z). Similarly fan boundaries handled.

One more check — F→V1b geometric: F heading → V1a (+38°); V1b at -38°: angle between F fwd (38°) and dir to V1b (-38°) = 76° > 70° cone ✗!!! F's heading points at V1a (+38°), so V1b is 76° off-axis → NOT triggered. Chain to lower branch dies!! FIX: F's heading should be +X (straight), with V1a at +38° and V1b at -38° — both within 70° cone ✔. But authored order gives F heading → V1a. Override F's heading to π/2 (fwd +X): heading convention atan2(fx,fz): +X = atan2(1,0) = π/2 ✔. Mark F with fork:true and override heading = π/2. Then cone: angle between +X and ±38° dirs = 38° ✔ both triggered. Also last main-line domino → F: consecutive ✔.

Also do V1a/V2a headings: authored consecutive → V2a, bezierA[0] ✔ fine.

3. Serpent turns: rows z0=-7.5, 11 rows → z max = -7.5+10·1.5=7.5 ✔. Turn: from row k end (13, z_k) — arc center (13, z_k+0.75), r=0.75: start point (13, z_k) is row's last domino; intermediate m=1..3 at s=m/4: a = -π/2 + s·π: m=1: a=-π/4 → (13+0.53, z+0.75-0.53)=(13.53, z+0.22); m=2: a=0 → (13.75, z+0.75); m=3: a=π/4 → (13.53, z+1.28); then row k+1 first domino at (13, z+1.5) ✔. Spacings: (13,z)→(13.53,z+0.22): 0.57 ✔; m1→m2: (0.22,0.53)=0.57 ✔; m2→m3: 0.57; m3→(13,z+1.5): (-0.53,0.22)=0.57 ✔ beautiful. Left turns: sgn=-1: a = -π/2 - sπ: m=1: a=-3π/4 → (-13-0.53, z+0.22) ✔ bulge -X ✔. Extents: 13.75 < 34 ✔. Count: 11·40 + 10·3 = 470 ✔.

x from -13 to 13 step 0.66: (13-(-13))/0.66 = 39.39 → for loop x<=13+1e-6 gives 40 points ✔ last at -13+39·0.66=12.74, hmm not exactly 13. Row ends at 12.74 ≠ turn start (13, z). Gap = 0.26?? No: turn center assumes row ends at x=13 but row actually ends at 12.74 → spacing from 12.74 to first arc point (13.53, z+0.22): dist = sqrt(0.79²+0.22²)=0.82 — slightly large but within trigger reach ✔ (dEff=0.82-0.16=0.66, θtrig=19.3° ✔). Fine. Or set x1 = x0 + 39·0.66 = 12.74 exactly and turn center at (x1, ...). Let me just compute xEnd = x0 + 39·0.66 and use xEnd in the turn math. I'll adjust: use loop that pushes while x <= 13, track actual last x. Simpler: define xs explicitly: nX=40, xEnd = x0+(nX-1)*step = -13+39·0.66 = 12.74. Turn centers at (±xEnd...). But right turns happen after +dir rows ending at 12.74; left turns after -dir rows ending at -13?? Asymmetric. Fix: make rows symmetric: x from -12.87 to 12.87 (nX=40, step=0.66: -12.87+39·0.66=12.87 ✔). Use xA=12.87 for both. Then turn center (±xA, z+0.75) r=0.75; extents 12.87+0.75=13.62 ✔.

4. Giant trigger from BOTH gates: ✔ geometric.

5. Complete condition: fallenCount >= N — but fallenCount increments only in fireTrigger; CLICKED/quaKED/toppleStart pushes (pushDomino) do NOT increment fallenCount! Then count never reaches N and HUD shows wrong fallen. Fix: increment fallenCount inside pushDomino too — but fireTrigger calls pushDomino-like logic inline (sets state=1 directly). Let me unify: make pushDomino the single place: fireTrigger calls pushDomino(j, omega) then does juice (sound/spark) — but pushDomino returns bool; on success do juice. Also lastFallPos/waveOrder/fallTimes update inside pushDomino. Let me refactor:

fireTrigger:

✔ fallenCount accurate.

Note ordering: fireTrigger marks t.fired=true even if j not standing (already fell) ✔ prevents repeated checks.

6. Reset during falling + re-trigger: resetCourse resets t.fired=false ✔, states → 3 → 0 ✔. During reset, pushDomino blocked ✔ (added resetting guard).

7. stepPhysics: alpha at θ=0 = (3G(0 - t))/(2(h²+t²)) < 0 → restoring ✔. Pushed with ω 1.05+ → climbs over balance atan(t/h)=8° ✔. Check energy: need ½Iω² > mgΔy to balance point: Δy_cm from θ=0 to θ_bal: y_cm(θ)= (t sinθ + h cosθ)/2; y(0)=h/2=1.0; y(8°)= (0.28·0.139 + 2·0.990)/2 = (0.039+1.98)/2=1.0096. Δy=0.0096. ω_needed: ½·(h²+t²)/3·ω² = g·Δy → ½·1.36·ω² = 0.0942 → ω² = 0.138 → ω = 0.37. Transfer gives ≥1.05 ✔✔ chains never die.

8. HUD speed calc: loop from end while <1s ✔.

9. Follow cam when nothing fell: guarded by firstFallT>=0 ✔.

10. completeT check with partial runs: second condition handles "all knocked down but maybe not via triggers" — but if user pushes ONE domino and it falls alone (chain dies elsewhere)... standing>0 → no complete ✔.

But hmm — what if the user clicks domino #300 only (state 1 → 2). fallenCount=1. Others stand. Fine.

11. onComplete when fallenCount>=N: with pushes unified, works ✔.

12. freqFor: 196·2^((i/(N-1))·24/12) = 196·2^(2·i/N) → range 196→784 ✔.

13. Raycaster with InstancedMesh and count < max: raycast respects count? In three r160, InstancedMesh.raycast iterates over this.count? It uses _instanceIntersects check with count... Actually Mesh raycast for InstancedMesh: _mesh.raycast per instance up to this.count ✔ (three r160 source: for ( let instanceId = 0; instanceId < count; instanceId ++ ) where count = this.count). ✔. But careful: instanceMatrix for indices ≥ N are identity (never written) → dominoes at origin of size 1 would be raycast-able... but count=N limits it ✔. However identity-scale-1 boxes... only if count > written — count = N and we wrote 0..N-1 ✔.

14. Shadow: domMesh with count=N ✔.

15. Bloom threshold 0.55 vs horizon ring: MeshBasicMaterial color 0x1de2ff toneMapped:false opacity 0.4 → luminance ~0.4·(0.11·0.11+... cyan lum ≈ 0.7·0.4=0.28 < 0.55 no bloom — ok subtle ring.

16. uEmissive pulse — dominoes glow ~0.2·color 0.56 ≈ 0.11 no bloom; armed: (0.2+1.8·1)·0.56 ≈ 1.12 → bloom ✔.

17. InstancedMesh + onBeforeCompile + shadows: depth material doesn't need glow ✔.

18. aGlow updates every frame for all N — 470 floats ✔ cheap.

19. reset theta for landed dominoes: thetaFrom = LAND for landed; during reset, state 3 dominoes rotate back ✔. Standing ones (state 0) skip (they get resetStart but state stays 0 — no visual change; in matrix loop state 3 only). But wait — resetCourse sets if (d.state !== 0) d.state = 3; ✔.

Also fallTimes reset ✔, firstFallT=-1 ✔ (so TIME display resets; but updateHUD shows time only if firstFallT>=0; elTime text remains stale until next fall — I set textContent '0.0s' at resetEnd ✔).

20. Quake during fall of others: allowed ✔.

21. Buttons on mobile: ok.

22. bindBtn('btnSound'): ensureAudio called before toggling — creates AC; then toggles soundOn and sets master.gain ✔. But initial ensureAudio inside bindBtn wrapper: for btnSound, first click creates audio with gain = soundOn? At creation soundOn=true → gain 0.55; then toggle sets soundOn=false, gain=0 ✔ consistent.

23. Space key scrolling: preventDefault ✔.

24. THREE.StereoPannerNode support ✔ modern browsers.

25. Potential NaN: Math.asin clamped ✔. heading for zero-length (duplicate points)? finalizeHeadings with identical consecutive points → atan2(0,0)=0 — acceptable; generators shouldn't produce duplicates. Spiral loop: phi increments 0.66/r > 0 ✔. Serpent: fine.

26. updateConfetti: when cnfLive 0 → cnfMesh.count stays CNF with zero-scale matrices — I set count=CNF on burst and never back to 0; dead ones have scale 0 ✔ invisible. Minor: initial count=0 ✔.

setColorAt on cnfMesh before first render? burstConfetti called on complete (after user interaction) — instanceColor created then ✔; but material compiled earlier without USE_INSTANCING_COLOR → program switch when instanceColor first set — three handles define change via needsUpdate? Setting mesh.instanceColor after render started requires material.needsUpdate... In three, WebGLPrograms keys include instancingColor based on object.instanceColor !== null — program is selected per render automatically; when it changes, new program compiled automatically ✔ (getProgram called per render, key changes → new program). It's automatic, no manual needsUpdate needed for object-level instancing color (material program cache key includes it). Actually to be safe, pre-initialize: after creating cnfMesh, loop setColorAt(i, white) once and set count=0. Then instanceColor exists from the start ✔. Same for domMesh: we setColorAt in buildCourse before first render ✔ buildCourse called before frame() ✔.

For cnfMesh I'll pre-fill colors at init.

27. _c reuse in spawnSpark calls: spawnSpark(..., _c.setRGB(...)) copies into spkBase ✔ immediate.

28. Land spark position: hinge + fwd·(h·0.7) — approx tip contact ✔.

29. Reset animation & glow: during reset fallenCount=0 → arr[0] beckon pulse might trigger on D[0] state 3? condition !resetting && D[0].state===0 ✔ guarded.

30. Order-based waveOrder with branches: wave glow approximates — fine visually since branch A is authored before branch B; wavefront jumps are OK.

31. LAND bounce condition: Math.abs(d.omega) > 0.9 — terminal ω ≈ 3+ → bounce once (ω→-0.4), then |ω|<0.9 → state 2, plus second thud at bounce===0? After bounce, bounce=1 → when re-landing: |ω|=0.4 <0.9 → else branch: state=2, if (d.bounce===0) playThud — bounce is 1 → no second thud ✔ good (already thudded at bounce).

Wait, actually there's a bug: bounce path plays thud ✔; settle path with bounce>0 plays nothing ✔.

32. Giant bounce shake ✔.

33. horizon TorusGeometry rotated x=π/2 — torus default lies in XY plane; rotate to XZ ✔.

34. Floor CircleGeometry radius 34 vs spiral r=15.2 ✔.

35. Fog 0.013 at distance 24 (camera) → exp(-0.013·24)=0.73 ✔ visible depth.

36. const glowDirty — unused leftover; remove to keep clean (it's harmless but let me clean it).

37. fan heading override loop bug:

gx needed in scope — define giant pos const. Also the LAST fan domino of last line: i+1 doesn't exist → skip; its authored heading from finalizeHeadings = direction from prev → falls outward ✔ (last element gets fallHeading default = direction from previous ✔). And first fan domino of each line (k=0): its heading authored → next (same line k=1) ✔ radial ✔. Only boundary-last-of-line needs override ✔. But ALSO: last fan domino of line m: authored next = first fan of line m+1 → handled ✔. What about the giant→fan start triggers: giant's heading +X; fan start positions: angles ±0.72 etc. — cone from giant: dir to fan start: angle fa... within 70°=1.22 rad ✔.

Additionally the giant may ALSO trigger fan dominoes of second row (radius 2.56): all within reach ✔ they'll fall too — that's fine, giant sweep knocks several — spectacular.

Wait, actually there's a subtle issue: giant falls onto fan area and will trigger maybe all 30 fan dominoes at slightly different θ — a radiating wave ✔ looks great.

38. Gate heading override: mark gate:true; after finalize, set heading toward giant: atan2(gx - x, 0 - z).

39. Fork heading override: fork:true → heading = π/2 (fwd +X).

40. Let me also double check trigger cone uses fwd / dist < CONE → skip: for heading directly at next (authored), fwd/dist = 1 ✔.

41. TRIG may include the PREVIOUS domino behind? dir to prev is backward → fwd<0 → skipped ✔.

42. Serpent lateral check: rows 1.5 apart; a falling domino in row k: dominoes in row k+1 are at lat 1.5 > 1.07 → excluded ✔. But dominoes in the SAME row behind: fwd negative ✔ excluded.

43. Instanced frustum culling: domMesh spans whole course; default boundingSphere of geometry (unit box) is wrong for instanced — three r160 InstancedMesh has computeBoundingSphere that accounts instances? In r160, InstancedMesh.computeBoundingSphere() exists and is called automatically? InstancedMesh has boundingSphere null by default; raycast uses it? For frustum culling, if boundingSphere null it's computed from geometry (wrong). r160: WebGLRenderer frustum-culls using object.boundingSphere if InstancedMesh? Actually in r156+, InstancedMesh has computeBoundingSphere and it's used in frustum culling (WebGLRenderer projectObject calls frustum.intersectsObject which uses geometry.boundingSphere... for InstancedMesh, intersectsObject checks object.boundingSphere if not null?). In r160, Frustum.intersectsObject: if (object.boundingSphere !== undefined) { if (object.boundingSphere === null) object.computeBoundingSphere(); ...} — yes r160 has this for InstancedMesh (it was added). So it computes from instances ✔. But after reset... positions static ✔ fine. To be extra safe I could set domMesh.frustumCulled = false. With one draw call it doesn't matter — set frustumCulled=false to avoid any pop. Same for sparks (done) ✔.

44. renderer.domElement pointer events vs OrbitControls: both listen; fine.

45. AudioContext on pointerdown anywhere ✔ (attached to canvas; buttons also ensureAudio).

46. Banner small tag styled ✔.

47. elSpeed unused var warning — used ✔.

48. In buildCourse, when switching courses mid-fall: D rebuilt, domMesh.count=N new; matrices written for all ✔. Confetti/sparks persist — fine.

49. updateHUD speed loop: fallTimes grows large over long runs (500 entries) — scanning from end breaks early ✔.

50. frame() perfT accumulation: perfT is seconds ✔ used in physics events ✔.

51. let steps=0; while acc>=DT && steps<8 — at 60fps dt=0.0167 → 2 steps ✔; after tab switch dt clamped 0.05 → 8 substeps max = 0.0667s... acc grows unbounded? acc -= DT per step; leftover acc remains; over time accumulates if consistently > capacity — with clamp dt 0.05 and 8·DT=0.0667 > 0.05 ✔ drains.

52. Reset while confetti falling — fine.

53. courseIdx button label: shows current in stats (courseName) ✔.

54. One more physics check — trigger angle for typical spacing 0.66: dEff = 0.66-0.14-0.02=0.5 → θtrig = asin(0.5/2)=14.5°. At θ=14.5°, tip height = 2·cos14.5°=1.94 → hits next domino high up ✔ looks right.

55. falling speed visual: ω ~3.5 rad/s → fall takes ~0.4s; chain wave at spacing 0.66 triggered at 14.5° — time between triggers ~0.05-0.1s → wave speed ~7-13 dominoes/s... hmm that feels slow-ish for 470 dominoes (~40-60s). Real domino waves accelerate. Our transfer ω grows: ω_j = 0.62·ω_i+1.05 → fixed point ω* = 1.05/0.38 = 2.76 rad/s. Time from push to trigger angle 14.5° with α growing... roughly 0.08-0.12s per domino → ~9/s → 470 dominoes ≈ 52s. Too slow! Increase energy transfer: ω_j = 0.75·ω_i + 1.35 → fixed point 5.4 rad/s; and reduce trigger angle? Trigger angle fixed by geometry. Also initial angular acceleration near θ=0 is small (α ≈ 3G(hθ-t)/(2(h²+t²))): at θ=0, α = -3·9.81·0.28/(2·4.08) = -1.01 (restoring); once past 8°, α grows positive. With ω=5 at trigger... time to fall from 0 to 14.5° starting at ω=2.76: average ω maybe 2.2 → 0.25rad/2.2 = 0.115s. Hmm. To get a snappier wave (~15-20/s at peak), boost transfer: ω_j = 0.8·ω_i + 1.6 → ω* = 8 rad/s. Then time per domino ≈ 0.25/((8+... start ω 8 → reaches 14.5° in ~0.035s → ~25/s peak. That's exciting. And landing ω ~ sqrt(ω²@trig + 2αΔ) ~ 10+ rad/s → fall duration ~0.2s. Multiple dominoes in flight overlapping ✔ realistic.

But high ω looks too violent? Dominoes in real chains fall FAST. I'll set transfer = 0.72·ω_i + 1.5 (ω* = 5.36) and TOPPLE initial push 2.2. Peak ~12-15/s. Good compromise. Also plays clicks as glissando — at 15/s sounds musical.

Also cap: ω_j = min(computed, 9).

56. Click volume at 15/s: compressor handles ✔ vol 0.26 each.

57. updateHUD fall speed text ✔.

58. Remove unused glowDirty.

59. const lastFallPos used before init? defined ✔.

60. _v reused in controls.target.lerp(_v.set(...)) and camera.position.lerp(_v.set(...))` — sequential use fine ✔.

61. In updateSparks, spkPos y clamp ≥0.02 with vel unchanged — sparks slide along floor; fine.

62. Confetti initial setColorAt pre-fill — add at init:

And count=0.

63. cnfMesh material transparent with instanceColor black — invisible initial ✔ count 0 anyway.

64. Shadow camera bounds ±26 covers courses ✔ (fan up to 15).

65. importmap + module scripts order ✔.

66. meta viewport ✔.

Also potential problem: finalizeHeadings for serpent: last domino of final row gets heading from previous (continue direction) ✔ falls into empty space ✔ fine.

Spiral last ring heading: authored next = giant ✔ auto.

Giant heading in spiral: fallHeading = atan2(-cos(a), -sin(a)) → fwd = (sin(h), cos(h)) = (-cos(a)·? sin(atan2(-cos a, -sin a)) = -cos a / 1, cos(...) = -sin a → fwd = (-cos a, -sin a) → pointing away from ring position at angle a (radially outward opposite side)... ring last at angle a, position (1.62cos a, 1.62 sin a); giant at origin; push direction from ring domino toward giant = -(cos a, sin a) normalized ✔ giant falls continuing past center to the other side ✔ natural.

67. Ring span: endA computed from phiMax; but the spiral's LAST point is at phi slightly less than phiMax (loop while phi<phiMax, increments). endA uses phiMax exact — tiny angular mismatch, distance check earlier used r=2.7 vs actual last r between 2.7 and 2.7+small — gap up to ~1.6 ✔ within reach.

Hmm wait: spiral loop pushes points while phi<phiMax with r = rOut - c·phi decreasing; last point r_last slightly > rIn=2.7 ✔.

68. Ring entry direction: spiral is clockwise inward (z = -r sinφ with φ increasing → angle decreasing = clockwise). Ring points at angles endA + k·step with step positive (counterclockwise!). The chain enters the ring and reverses rotational direction?? The last spiral domino heading → ring[0] auto ✔ regardless. Ring dominoes chain counterclockwise ✔ their headings auto. Visually fine — spiral comes in, ring sweeps around other way. OK.

69. Also — the ring is centered at origin with the spiral path crossing nearby: a falling ring domino might geometrically trigger nearby SPIRAL dominoes that are still standing (already fell behind? Spiral fell already since ring comes after in chain — all spiral dominoes are state 2 ✔ skipped). But what if user clicks a RING domino first? Ring circle chains around, last ring domino → giant falls ✔, spiral untouched → partial run ✔ no complete (standing>0) ✔.

70. updateHUD before buildCourse? buildCourse called before frame ✔ elements exist ✔.

71. document.getElementById('btnCam').click() inside keydown triggers bindBtn wrapper → ensureAudio ✔ toggles ✔.

72. Small: bindBtn wrapper calls ensureAudio for all buttons including sound — fine.

73. iOS Safari: importmap OK modern; AudioContext webkit prefix handled ✔.

Now rewrite the twin split generator properly with bezier, fix fork/gate heading overrides, unify pushDomino counting, boost transfer constants, pre-fill confetti colors, set domMesh.frustumCulled=false, remove glowDirty, fix serpent x symmetry. Let me apply these edits.

Also item 55 constants: transfer 0.72 * di.omega * ratio + 1.5, cap 9; topple push 2.2; click push 1.8 ok; quake 1.3-2.3 ok.

Also fix: in fireTrigger, playClick uses dj.order ✔.

Serpent: nX=40, xA = 12.87: xs from -xA + k·0.66, k<40 → last = -12.87+39·0.66=12.87 ✔ symmetric.

Let me now apply all fixes with targeted replacements. Several regions to change:

A. genSerpent — rewrite symmetric version. B. genTwinSplit — rewrite with bezier + flags. C. finalizeHeadings overrides for fork/gate (do in genTwinSplit post-loop like fan). D. pushDomino unify + fireTrigger refactor. E. Confetti pre-fill + frustumCulled false on domMesh. F. Remove glowDirty. G. Transfer constants.

Let me do these replacements carefully.

I'm at 61% of max time budget already?? timeProgress 0.6147. I should hurry. Let me quickly make the remaining edits: rewrite genTwinSplit, unify pushDomino counting, boost transfer constants, minor fixes, then update index page and finish. Let me batch several edits in parallel calls where independent (same file edits are not fully independent but replacements target distinct unique strings — they can run sequentially; to be safe do them in one batch since they touch different unique anchors — parallel edits to the same file could conflict. I'll do them sequentially but quickly, combining multiple replacements per call is not supported. Let me prioritize:

1. genTwinSplit rewrite (critical for course 3).
2. pushDomino counting + fireTrigger (critical for complete detection).
3. Transfer constants (gameplay feel).
4. domMesh.frustumCulled=false + confetti prefill (minor, can skip if needed but quick).
5. Index page update (required).

Go.

89% time used. I must move very fast. Remaining critical edits:

1. pushDomino counting + fireTrigger (critical).
2. Transfer constant boost (feel, one line).
3. Index page update (required).

Skip minor fixes (frustumCulled, confetti prefill, glowDirty) to save time — they're non-fatal. Actually confetti setColorAt-after-start program switch is automatic in three, fine.

Do edit 1 and 2 now (both in same region, can do in two calls), then index update, then a quick syntax check if time, then success. Let me batch edit 1+2 as two replace calls in one block — they're independent anchors in the same file... risk: parallel writes to same file could race. Better sequential. But time... The tool calls in one block run concurrently — same-file edits might clobber. I'll do them one at a time but no status checks between.

*************************************************************************************************************************************************************************nt.

***********************************************************************************************>".

Whitespace mismatch. Let me check the exact text around the marker.

Index updated. Now quick syntax validation of the demo JS, then done. Extract the module script and run node --check.

Syntax OK. One last sanity check: the leftover unused glowDirty variable — harmless. elSpeed etc fine. freqFor exists. In buildCourse, _c.setHSL used. In fireTrigger, dj referenced for juice ✔. spawnSpark _c.setHSL(0.55 - 0.4*(dj.order/N), ...) fine.

One thing: in the juice code after pushDomino in fireTrigger — if (!pushDomino(t.j, kick)) return; then playClick(... dj ...) ✔ dj defined.

Everything critical is done: demo file created, index updated, syntax valid. Call _success.