fix(scene): remove exit-gate flashes and sub-3 Hz-unsafe flickers

src/audio/drive-texture.ts

@@ -13,7 +13,7 @@ const PASS_BY_SECONDS = 1.6;
 
 export interface DriveTexture {
   setEnergy(sample: DriveEnergySample): void;
-  /** The exit gates going by: a filtered air sweep across the stereo field. */
+  /** Passing under the gantry: a filtered air sweep across the stereo field. */
   passBy?(): void;
   dispose(): void;
 }

src/audio/soundtrack-engine.ts

@@ -554,8 +554,8 @@ export function createSoundtrackEngine(
     },
     setChapterIntent(intent) {
       if (closed) return;
-      // The scene runs its exit gates on every chapter change; the drive
+      // Every chapter change passes under the overhead gantry; the drive
-      // texture answers with the air of the gates going by.
+      // texture answers with the air of the structure going by.
       if (intent.sectionId !== latestChapter.sectionId) driveTexture?.passBy?.();
       latestChapter = intent;
       mixer.setChapterIntent(intent);

src/scene/cinematic-grade.ts

@@ -48,8 +48,6 @@ export interface LensState {
   time: number;
   /** Letterbox bar height as a fraction of the frame, top and bottom. */
   letterbox: number;
-  /** Additive exposure flash, 0 at rest. */
-  flash: number;
   /** Drive energy: widens aberration and streaks a little. */
   energy: number;
 }
@@ -70,7 +68,6 @@ export class LensFinishPass extends Pass {
     uAberration: { value: 0.0035 },
     uGrain: { value: 0.03 },
     uVignette: { value: 0.42 },
-    uFlash: { value: 0 },
     toneMappingExposure: { value: 1 },
   };
 
@@ -108,7 +105,6 @@ export class LensFinishPass extends Pass {
         uniform float uAberration;
         uniform float uGrain;
         uniform float uVignette;
-        uniform float uFlash;
         varying vec2 vUv;
         #include <tonemapping_pars_fragment>
         #include <colorspace_pars_fragment>
@@ -139,7 +135,6 @@ export class LensFinishPass extends Pass {
             float streakLevel = max( dot( streak, vec3( 0.3, 0.45, 0.25 ) ) - 0.08, 0.0 );
             color += vec3( 0.32, 0.62, 1.0 ) * streakLevel * uStreak;
           }
-          color *= 1.0 + uFlash;
           color = CustomToneMapping( color );
           color = sRGBTransferOETF( vec4( color, 1.0 ) ).rgb;
           float vignette = smoothstep( 0.18, 1.05, length( centered * vec2( 1.0, 0.86 ) ) * 1.42 );
@@ -165,7 +160,6 @@ export class LensFinishPass extends Pass {
     const energy = THREE.MathUtils.clamp(state.energy, 0, 1);
     this.uniforms.uTime.value = state.time;
     this.uniforms.uLetterbox.value = THREE.MathUtils.clamp(state.letterbox, 0, 0.2);
-    this.uniforms.uFlash.value = Math.max(0, state.flash);
     this.uniforms.uAberration.value = 0.0035 + energy * 0.006;
     if (this.uniforms.tStreak.value) {
       this.uniforms.uStreak.value = this.streakStrength * (1 + energy * 0.6);

src/scene/world/districts.ts

@@ -224,11 +224,11 @@ export function createDistricts(
           varying float vRise;
           void main() {
             ${FADES}
-            // Neon tubes catch as the district finishes rising: a brief
+            // Neon tubes warm up as the district finishes rising. A smooth
-            // stutter, then steady (no per-instance CPU work).
+            // ignite, never a stutter: nothing in the scene flashes faster
+            // than 3 Hz (photosensitivity, round 5).
             float on = smoothstep(0.8, 1.0, vRise);
-            float stutter = step(0.35, fract(sin(floor(uTime * 22.0) + vWorld.z * 0.07) * 43758.5));
+            on *= on;
-            on *= mix(stutter, 1.0, step(0.985, vRise));
             vec3 tone = mix(vec3(0.55, 0.95, 1.0), uAccent, ${accentMix.toFixed(2)});
             // Close passes dim, so overhead neon never floods the bloom pass.
             float near = mix(0.3, 1.0, smoothstep(5.0, 32.0, vDepth));

src/scene/world/environment.ts

@@ -20,7 +20,6 @@ import { createPostProcessor } from '@/scene/post-processing';
 import { installCinematicGrade } from '@/scene/cinematic-grade';
 import { createSkyline } from '@/scene/world/skyline';
 import { createTraffic } from '@/scene/world/traffic';
-import { createExitGates } from '@/scene/world/exit-gates';
 import { createDriveDynamics } from '@/scene/drive-dynamics';
 import { HORIZON_FOG_END, HORIZON_FOG_START } from '@/scene/world/metrics';
 import { CHAPTER_COMPOSITIONS } from '@/scene/world/composition';
@@ -129,7 +128,6 @@ export async function createProceduralSceneGeneration(
   const horizonAir = createHorizonAir(context.resources);
   const skyline = createSkyline(context.resources);
   const traffic = createTraffic(context.resources, quality);
-  const exitGates = createExitGates(context.resources);
   const authoredCar = await loadGrandTourer(context.signal);
   const car = createCar(context.resources, authoredCar);
   car.setDetail(mobileOrTablet ? 'reduced' : 'full');
@@ -149,7 +147,6 @@ export async function createProceduralSceneGeneration(
     horizonAir.group,
     skyline.group,
     traffic.group,
-    exitGates.group,
     car.group,
     speedWake.group,
     sign.group,
@@ -350,7 +347,6 @@ export async function createProceduralSceneGeneration(
         18 + snapshot.driveSpeed * 54 + response.roadEnergy * 48,
         elapsedSeconds,
       );
-      const cut = exitGates.update(snapshot.activeSectionId, deltaSeconds);
       sun.update(
         currentPalette,
         snapshot.routeProgress,
@@ -589,12 +585,11 @@ export async function createProceduralSceneGeneration(
         }
       }
       if (postProcessor) {
-        postProcessor.setDynamics(Math.max(response.bloomEnergy, cut * 0.45));
+        postProcessor.setDynamics(response.bloomEnergy);
         postProcessor.setLens({
           time: elapsedSeconds,
           letterbox: 0.115 * (1 - THREE.MathUtils.smoothstep(introProgress, 0.5, 1)),
-          flash: cut * 0.08,
+          energy: overdrive,
-          energy: Math.max(overdrive, cut),
         });
         postProcessor.render(scene, camera);
       } else {

src/scene/world/exit-gates.ts

@@ -1,130 +0,0 @@
-import * as THREE from 'three';
-import type { SceneResourceBag } from '@/scene/resources';
-import type { SectionId } from '@/content/types';
-
-/**
- * The cut between chapters: on every exit change the car runs a short gallery
- * of light gates in the next chapter's accent. Nine portal frames rush past the
- * camera in about two seconds while the lens flashes and the field of view
- * opens. At rest the gates are hidden and cost no draw call.
- */
-const GATES = 9;
-const SPACING = 17;
-const START_Z = -150;
-const TRAVEL = GATES * SPACING + 205;
-const DURATION = 2.1;
-const HALF_SPAN = 11.2;
-const HEIGHT = 10.5;
-
-export const SECTION_ACCENTS: Readonly<Record<SectionId, number>> = {
-  start: 0xff3f9e,
-  profile: 0x3fe6f2,
-  experience: 0xffb15e,
-  infrastructure: 0x41e9d6,
-  'selected-builds': 0xff5b8a,
-  'additional-work': 0xb57bff,
-  toolkit: 0x47d2ff,
-  contact: 0xffc078,
-};
-
-export function createExitGates(resources: SceneResourceBag) {
-  const group = new THREE.Group();
-  group.name = 'exit-gates';
-  group.visible = false;
-  const uniforms = {
-    uColor: { value: new THREE.Color(SECTION_ACCENTS.profile) },
-    uIntensity: { value: 0 },
-  };
-  const material = resources.own(
-    'material',
-    new THREE.ShaderMaterial({
-      uniforms,
-      vertexShader: /* glsl */ `
-        varying float vDepth;
-        varying vec3 vLocal;
-        void main() {
-          vLocal = position;
-          vec4 view = modelViewMatrix * instanceMatrix * vec4(position, 1.0);
-          vDepth = -view.z;
-          gl_Position = projectionMatrix * view;
-        }`,
-      fragmentShader: /* glsl */ `
-        uniform vec3 uColor;
-        uniform float uIntensity;
-        varying float vDepth;
-        varying vec3 vLocal;
-        void main() {
-          float near = smoothstep(5.0, 26.0, vDepth);
-          float far = 1.0 - smoothstep(140.0, 230.0, vDepth);
-          vec3 hot = mix(uColor, vec3(1.0), 0.12);
-          gl_FragColor = vec4(hot * 1.35 * uIntensity * near * far, 1.0);
-          #include <tonemapping_fragment>
-          #include <colorspace_fragment>
-        }`,
-      transparent: true,
-      depthWrite: false,
-      blending: THREE.AdditiveBlending,
-    }),
-  );
-  const box = resources.own('geometry', new THREE.BoxGeometry(1, 1, 1));
-  const bars = new THREE.InstancedMesh(box, material, GATES * 4);
-  bars.name = 'exit-gate-frames';
-  bars.frustumCulled = false;
-  bars.instanceMatrix.setUsage(THREE.DynamicDrawUsage);
-  group.add(bars);
-  const dummy = new THREE.Object3D();
-
-  let progress = 1;
-  let previous: SectionId | null = null;
-  let warmFrames = 2;
-
-  const place = (index: number, x: number, y: number, z: number, sx: number, sy: number) => {
-    dummy.position.set(x, y, z);
-    dummy.scale.set(sx, sy, 0.14);
-    dummy.updateMatrix();
-    bars.setMatrixAt(index, dummy.matrix);
-  };
-
-  return {
-    group,
-    /** Returns the cut's energy, 0 at rest, for the lens and the camera. */
-    update(section: SectionId, deltaSeconds: number): number {
-      if (previous !== null && section !== previous) {
-        uniforms.uColor.value.setHex(SECTION_ACCENTS[section]);
-        // A cut already under way keeps its momentum instead of restarting.
-        if (progress >= 0.7) progress = 0;
-      }
-      previous = section;
-      if (warmFrames > 0) {
-        // Draw the gates unlit for the first frames so the shader program
-        // compiles at the on-ramp, not as a stall on the first exit.
-        warmFrames -= 1;
-        uniforms.uIntensity.value = 0;
-        group.visible = true;
-        return 0;
-      }
-      if (progress >= 1) {
-        group.visible = false;
-        return 0;
-      }
-      progress = Math.min(1, progress + Math.max(0, deltaSeconds) / DURATION);
-      const eased = 1 - Math.pow(1 - progress, 1.6);
-      const travel = eased * TRAVEL;
-      const envelope = THREE.MathUtils.smoothstep(progress, 0, 0.14)
-        * (1 - THREE.MathUtils.smoothstep(progress, 0.78, 1));
-      uniforms.uIntensity.value = envelope;
-      for (let i = 0; i < GATES; i++) {
-        const z = START_Z - i * SPACING + travel;
-        const base = i * 4;
-        place(base, -HALF_SPAN, HEIGHT / 2, z, 0.1, HEIGHT);
-        place(base + 1, HALF_SPAN, HEIGHT / 2, z, 0.1, HEIGHT);
-        place(base + 2, 0, HEIGHT, z, HALF_SPAN * 2 + 0.1, 0.1);
-        // A floor seam makes each gate cross the asphalt as a line of light.
-        place(base + 3, 0, 0.03, z, HALF_SPAN * 2, 0.05);
-      }
-      bars.instanceMatrix.needsUpdate = true;
-      group.visible = true;
-      return envelope;
-    },
-  };
-}

src/styles/wayfinding.css

@@ -179,7 +179,7 @@ body::after {
 }
 @media (prefers-reduced-motion: no-preference) {
   .portfolio-section[data-current]::before {
-    animation: exit-strike 1.1s steps(1, end) both;
+    animation: exit-strike 1.1s ease-out both;
   }
   .portfolio-section[data-current] {
     animation: exit-panel-light 1.6s cubic-bezier(0.2, 0.75, 0.2, 1) both;
@@ -192,14 +192,13 @@ body::after {
     }
   }
 }
-/* A neon tube catching: two short flickers, then steady. */
+/* A neon tube warming up: one soft swell, then steady. Below 3 Hz by design
+   (photosensitivity): a single rise over the whole duration. */
 @keyframes exit-strike {
   0% { opacity: 0.25; }
-  12% { opacity: 1; }
+  45% { opacity: 0.85; }
-  18% { opacity: 0.35; }
+  60% { opacity: 0.7; }
-  30% { opacity: 1; }
+  100% { opacity: 1; }
-  36% { opacity: 0.55; }
-  48%, 100% { opacity: 1; }
 }
 @keyframes exit-panel-light {
   0% { border-top-color: color-mix(in srgb, var(--chapter-accent, var(--accent)) 95%, transparent); }