/* ============================================================================
 * Aquatic World — the application: environment, frame graph, boot.
 *
 * The frame is: derive the sun from the clock → advance simulations → render
 * the scene twice (once mirrored for reflections, once for real) → run the
 * post chain → blit to the canvas.
 *
 * Core also ships three deliberately minimal fallback passes. If a content
 * module is missing or fails to compile, the world still renders as an ocean
 * instead of a black rectangle, and `AW.app.errors` says exactly what is
 * absent — a failure you can look at is far easier to fix than a blank screen.
 * ==========================================================================*/

const { clamp, lerp, damp, smoothstep, TAU, DEG } = AW.math;

const bootHooks = [];
AW.app.onBoot = (fn) => bootHooks.push(fn);

/* ------------------------------------------------- environment (sun/moon) */

// East is +X, north is -Z. Hour angle runs from solar noon, so timeOfDay 12
// puts the sun at its highest and 6/18 at the horizon.
function celestialBody(timeOfDay, latitudeDeg) {
  const lat = latitudeDeg * DEG;
  const dec = 0;                                   // equinox; a fixed declination keeps the arc predictable
  const H = (timeOfDay - 12) * 15 * DEG;
  const sinAlt = Math.sin(lat) * Math.sin(dec) + Math.cos(lat) * Math.cos(dec) * Math.cos(H);
  const alt = Math.asin(clamp(sinAlt, -1, 1));
  const cosAlt = Math.cos(alt);
  const denom = cosAlt * Math.cos(lat);
  const cosAz = denom > 1e-6
    ? clamp((Math.sin(dec) - Math.sin(alt) * Math.sin(lat)) / denom, -1, 1) : 1;
  let az = Math.acos(cosAz);
  if (H > 0) az = TAU - az;                        // afternoon: mirror to the west
  return [cosAlt * Math.sin(az), Math.sin(alt), -cosAlt * Math.cos(az)];
}

const _sun = [0, 1, 0], _moon = [0, 1, 0];
const _sunTint = [1, 1, 1];
const _ambient = [0, 0, 0];

function updateEnvironment() {
  const s = AW.settings;
  const u = AW.uniforms;

  AW.v3.norm(celestialBody(s.timeOfDay, s.latitude), _sun);
  AW.v3.norm(celestialBody(s.timeOfDay + 12, s.latitude), _moon);

  // Sunlight ramps up through civil twilight and reddens as it approaches the
  // horizon; both terms are in linear HDR and get tonemapped later.
  const elevation = _sun[1];
  const day = smoothstep(-0.09, 0.20, elevation);
  const warm = smoothstep(-0.02, 0.26, elevation);
  _sunTint[0] = lerp(1.00, 1.00, warm);
  _sunTint[1] = lerp(0.34, 0.96, warm);
  _sunTint[2] = lerp(0.10, 0.92, warm);

  const sunPower = 13.5 * day * (0.35 + 0.65 * warm);
  u.uSunColor = [_sunTint[0] * sunPower, _sunTint[1] * sunPower, _sunTint[2] * sunPower];
  u.uSunDir = _sun;

  const moonUp = smoothstep(-0.04, 0.16, _moon[1]);
  const moonPower = 0.42 * moonUp;
  u.uMoonDir = _moon;
  u.uMoonColor = [0.42 * moonPower, 0.52 * moonPower, 0.78 * moonPower];

  // Ambient sky irradiance: blue by day, near-black by night, with a warm
  // floor around sunrise so nothing ever reads as pure black.
  const amb = lerp(0.035, 1.0, day);
  _ambient[0] = amb * lerp(0.055, 0.34, day) + 0.02 * moonUp;
  _ambient[1] = amb * lerp(0.065, 0.42, day) + 0.025 * moonUp;
  _ambient[2] = amb * lerp(0.095, 0.55, day) + 0.045 * moonUp;
  u.uAmbient = _ambient;

  u.uTurbidity = s.turbidity;
  u.uExposure = s.exposure;
  u.uWindDir = [Math.cos(s.windDir * DEG), Math.sin(s.windDir * DEG)];
  u.uWindSpeed = s.windSpeed;
  // Waves grow with wind but saturate, so a storm is rough rather than absurd.
  u.uWaveAmp = s.waveAmp * clamp(Math.sqrt(s.windSpeed / 9), 0.35, 2.1);
  u.uChoppiness = s.choppiness;
  u.uFogDensity = s.fogDensity;
  u.uBloomStrength = s.bloom;
  u.uVignette = 0.34;
  u.uChroma = s.chroma;
  u.uQuality = s.quality;
  u.uUnderwater = AW.cam.underwater ? 1 : 0;
}

/* ------------------------------------------------------ fallback shaders */

// Registered unconditionally so they are always compilable; the passes that
// use them switch themselves off the moment a real module claims the name.
AW.shaders.fsCoreSky = `
in vec2 vUV;
uniform mat4 uInvViewProj;
uniform vec3 uCamPos;
uniform vec3 uSunDir;
uniform vec3 uSunColor;
uniform vec3 uAmbient;
out vec4 fragColor;

void main() {
  vec4 p = uInvViewProj * vec4(vUV * 2.0 - 1.0, 1.0, 1.0);
  vec3 d = normalize(p.xyz / p.w - uCamPos);
  float up = clamp(d.y, 0.0, 1.0);
  vec3 sky = mix(uAmbient * 1.6 + vec3(0.30, 0.40, 0.52),
                 uAmbient * 0.9 + vec3(0.05, 0.14, 0.36), pow(up, 0.55));
  float s = max(dot(d, normalize(uSunDir)), 0.0);
  sky += uSunColor * (pow(s, 1800.0) * 6.0 + pow(s, 10.0) * 0.05);
  fragColor = vec4(max(sky, vec3(0.0)), 1.0);
}
`;

AW.shaders.fsCoreWater = `
in vec2 vUV;
uniform mat4 uInvViewProj;
uniform vec3 uCamPos;
uniform vec3 uSunDir;
uniform vec3 uSunColor;
uniform vec3 uAmbient;
uniform vec2 uRes;
uniform float uSeaLevel;
uniform float uUnderwater;
uniform float uTime;
uniform sampler2D uSceneTex;
uniform sampler2D uReflectTex;
out vec4 fragColor;

vec3 skyFallback(vec3 d) {
  float up = clamp(d.y, 0.0, 1.0);
  vec3 sky = mix(uAmbient * 1.6 + vec3(0.30, 0.40, 0.52),
                 uAmbient * 0.9 + vec3(0.05, 0.14, 0.36), pow(up, 0.55));
  float s = max(dot(d, normalize(uSunDir)), 0.0);
  return sky + uSunColor * (pow(s, 1800.0) * 6.0 + pow(s, 10.0) * 0.05);
}

void main() {
  vec4 p = uInvViewProj * vec4(vUV * 2.0 - 1.0, 1.0, 1.0);
  vec3 ro = uCamPos;
  vec3 rd = normalize(p.xyz / p.w - ro);

  if (uUnderwater > 0.5 || rd.y > -0.0005) { fragColor = texture(uSceneTex, vUV); return; }
  float t = (uSeaLevel - ro.y) / rd.y;
  if (t <= 0.0) { fragColor = texture(uSceneTex, vUV); return; }
  vec3 wp = ro + rd * t;

  // A cheap but shapely normal: crossed sine trains at two scales.
  vec2 q = wp.xz;
  vec2 g = vec2(cos(dot(q, vec2(0.31, 0.22)) + uTime * 1.3),
                sin(dot(q, vec2(-0.26, 0.37)) + uTime * 1.1)) * 1.5;
  g += vec2(sin(dot(q, vec2(0.83, -0.51)) + uTime * 2.1),
            cos(dot(q, vec2(0.61, 0.74)) + uTime * 1.9)) * 0.7;
  vec3 n = normalize(vec3(-g.x * 0.09, 1.0, -g.y * 0.09));

  vec3 view = -rd;
  float fres = 0.02 + 0.98 * pow(1.0 - clamp(dot(n, view), 0.0, 1.0), 5.0);

  vec3 refl = skyFallback(reflect(rd, n));
  vec2 ruv = vUV + n.xz * 0.10;
  vec3 reflPlanar = texture(uReflectTex, clamp(ruv, 0.0, 1.0)).rgb;
  refl = mix(refl, reflPlanar, clamp(fres * 1.2, 0.0, 0.92));

  vec3 below = texture(uSceneTex, clamp(vUV + n.xz * 0.055, 0.0, 1.0)).rgb;
  below = mix(below * vec3(0.18, 0.52, 0.62), below * vec3(0.05, 0.30, 0.45), 0.5);

  float spec = pow(max(dot(reflect(-normalize(uSunDir), n), view), 0.0), 240.0);
  vec3 col = mix(below, refl, fres) + uSunColor * spec * 0.9;
  fragColor = vec4(col, 1.0);
}
`;

AW.shaders.fsBlit = `
in vec2 vUV;
uniform sampler2D uSource;
out vec4 fragColor;
void main() { fragColor = vec4(texture(uSource, vUV).rgb, 1.0); }
`;

AW.shaders.fsCoreComposite = `
in vec2 vUV;
uniform sampler2D uWaterTex;
uniform float uExposure;
uniform vec3 uAmbient;
out vec4 fragColor;

vec3 aces(vec3 x) {
  const float a = 2.51, b = 0.03, c = 2.43, d = 0.59, e = 0.14;
  return clamp((x * (a * x + b)) / (x * (c * x + d) + e), 0.0, 1.0);
}

void main() {
  vec3 col = texture(uWaterTex, vUV).rgb;
  vec2 d = vUV - 0.5;
  col *= 1.0 - dot(d, d) * 0.32;
  col = aces(col * uExposure);
  fragColor = vec4(pow(col, vec3(1.0 / 2.2)), 1.0);
}
`;

/* -------------------------------------------------------- fallback passes */

function hasRealPass(name) { return !!AW.passes.get(name); }

AW.passes.add({
  name: '_coreSky', order: 4, phase: 'scene', reflect: true,
  enabled: () => !hasRealPass('sky'),
  run(ctx) {
    const p = AW.gl.program('_coreSky', { vs: ['awVsCommon'], fs: ['fsCoreSky'] });
    p.use();
    AW.gl.depthTest(true);
    AW.gl.depthWrite(true);
    AW.gl.blend('none');
    AW.gl.drawFullscreen();
  },
});

AW.passes.add({
  name: '_coreWater', order: 41, phase: 'scene', reflect: false,
  enabled: () => !hasRealPass('water'),
  run(ctx) {
    const p = AW.gl.program('_coreWater', { vs: ['awVsCommon'], fs: ['fsCoreWater'] });
    AW.rt('water').bind();
    AW.gl.baseline();
    AW.gl.depthTest(false);
    AW.gl.depthWrite(false);
    p.use();
    AW.gl.drawFullscreen();
    ctx.loaded = true;
  },
});

AW.passes.add({
  name: '_coreComposite', order: 899, phase: 'post',
  enabled: () => !hasRealPass('composite'),
  run(ctx) {
    const p = AW.gl.program('_coreComposite', { vs: ['awVsCommon'], fs: ['fsCoreComposite'] });
    AW.rt('ldr').bind();
    AW.gl.baseline();
    AW.gl.depthTest(false);
    AW.gl.depthWrite(false);
    p.use();
    AW.gl.drawFullscreen();
  },
});

/* --------------------------------------------------------------- targets */

function declareTargets() {
  const g = AW.gl;
  g.rt('scene', { scale: 1.0, format: 'rgba16f', depth: true, msaa: 4 });
  g.rt('reflect', { scale: 0.5, format: 'rgba16f', depth: true, msaa: 0 });
  g.rt('water', { scale: 1.0, format: 'rgba16f', msaa: 0 });
  g.rt('bloomA', { scale: 0.25, format: 'rgba16f', msaa: 0 });
  g.rt('bloomB', { scale: 0.25, format: 'rgba16f', msaa: 0 });
  g.rt('ldr', { scale: 1.0, format: 'rgba8', msaa: 0 });
}

/* ------------------------------------------------------------------ boot */

AW.app.initUniforms = function () {
  const u = AW.uniforms;
  u.uTime = 0;
  u.uRealTime = 0;
  u.uFrame = 0;
  u.uRes = [1, 1];
  u.uPix = [1, 1];
  u.uAspect = 1;
  u.uSeed = AW.settings.seed;
  u.uQuality = AW.settings.quality;
  u.uSeaLevel = 0;
  u.uUnderwater = 0;
  u.uClipPlane = [0, 0, 0, 1e9];
  u.uCamPos = AW.cam.pos;
  u.uCamDir = AW.cam.fwd;
  u.uCamRight = AW.cam.right;
  u.uCamUp = AW.cam.up;
  u.uNear = AW.cam.near;
  u.uFar = AW.cam.far;
  u.uProj = AW.cam.proj;
  u.uView = AW.cam.view;
  u.uViewProj = AW.cam.viewProj;
  u.uInvViewProj = AW.cam.invViewProj;
  u.uPrevViewProj = AW.app.prevViewProj;
  u.uSunDir = [0, 1, 0];
  u.uSunColor = [1, 1, 1];
  u.uMoonDir = [0, -1, 0];
  u.uMoonColor = [0, 0, 0];
  u.uAmbient = [0.1, 0.12, 0.16];
  u.uTurbidity = AW.settings.turbidity;
  u.uExposure = AW.settings.exposure;
  u.uWindDir = [1, 0];
  u.uWindSpeed = AW.settings.windSpeed;
  u.uWaveAmp = AW.settings.waveAmp;
  u.uChoppiness = AW.settings.choppiness;
  u.uFogDensity = AW.settings.fogDensity;
  // Coastal-to-open-ocean default optics. Red is extinguished roughly ten
  // times faster than blue, which is what makes depth read as depth.
  u.uWaterAbsorb = [0.32, 0.062, 0.038];
  u.uWaterScatter = [0.020, 0.085, 0.115];
  u.uWaterScatterAniso = 0.72;
  u.uRefractIndex = 1.333;
  u.uBloomStrength = AW.settings.bloom;
  u.uVignette = 0.34;
  u.uChroma = AW.settings.chroma;
};

AW.app.prevViewProj = AW.m4.create();
AW.app.lastMainViewProj = AW.m4.create();

// The auto-bound samplers resolve through AW.uniforms, so the app owns
// pointing them at live textures.
//
// This runs every frame rather than once at boot, because a pass is free to
// declare or re-fit its own targets at any time and `fit()` reallocates. A
// stale reference here is the worst kind of bug: sampling a deleted texture
// returns black with no error, no warning, and a plausible-looking dark image.
// Re-running costs six comparisons and no GL calls.
function bindTargetUniforms() {
  const u = AW.uniforms, rt = AW._rts;
  if (!rt.scene || !rt.scene.tex) return;
  u.uSceneTex = rt.scene.tex;
  u.uDepthTex = rt.scene.depthTex;
  u.uReflectTex = rt.reflect.tex;
  u.uWaterTex = rt.water.tex;
  u.uBloomTex = rt.bloomA.tex;
}
AW.app.bindTargetUniforms = bindTargetUniforms;

AW.app.resize = function () {
  const c = AW.app.canvas;
  if (!c) return;
  const dpr = Math.min(window.devicePixelRatio || 1, 2);
  const cssW = c.clientWidth || window.innerWidth || 1280;
  const cssH = c.clientHeight || window.innerHeight || 720;
  let w = Math.max(4, Math.round(cssW * dpr));
  let h = Math.max(4, Math.round(cssH * dpr));
  // Cap the pixel count: past ~2.3 MP the raymarch cost outweighs the detail.
  const MAX_PIXELS = 1920 * 1200;
  if (w * h > MAX_PIXELS) {
    const k = Math.sqrt(MAX_PIXELS / (w * h));
    w = Math.max(4, Math.round(w * k));
    h = Math.max(4, Math.round(h * k));
  }
  // Re-fit only when the size actually changed — but publish the uniforms
  // unconditionally. index.html pre-sizes the canvas, so at exactly that size
  // nothing needs reallocating and an early return here is tempting; doing that
  // used to leave uRes/uPix/uAspect at their initial [1,1] / 1.0 for the whole
  // session. Every pixel-footprint effect in the project reads them, so
  // "sub-pixel" dispersion silently became a ~1000 px channel shift and every
  // detail LOD was off by the resolution. Publish first, then decide.
  if (w !== c.width || h !== c.height) {
    c.width = w; c.height = h;
    AW.gl.fitTargets(w, h);
    AW.log('resize', w + 'x' + h);
  }
  bindTargetUniforms();
  AW.app.aspect = w / h;
  AW.app.res = [w, h];
  AW.uniforms.uRes = AW.app.res;
  AW.uniforms.uPix = [1 / w, 1 / h];
  AW.uniforms.uAspect = w / h;
};

AW.app.boot = function () {
  if (AW.app.booted) return;
  AW.app.booted = true;

  const canvas = document.getElementById('aw-canvas') || document.querySelector('canvas');
  if (!canvas) { AW.error('boot', 'no canvas element found'); return; }
  // Belt and braces: the stylesheet may not have loaded yet, and a canvas with
  // default sizing would silently render the world at 300x150.
  canvas.style.display = 'block';
  canvas.style.width = '100%';
  canvas.style.height = '100%';

  AW.app.canvas = canvas;
  if (!AW.gl.init(canvas)) return;

  AW.input.init(canvas);
  declareTargets();
  AW.app.initUniforms();
  AW.app.resize();
  // resize() early-returns when the canvas already has the right size, which
  // it does here whenever the width/height attributes match the layout. Force
  // the allocation so targets are never 0x0 on the first frame.
  AW.gl.fitTargets(canvas.width, canvas.height);
  bindTargetUniforms();

  for (const hook of bootHooks) AW.try('bootHook', hook);
  AW.log('booted', AW.gl.caps.colorBufferFloat ? 'HDR' : 'LDR-only', AW.gl.caps.maxSamples + 'x MSAA max');

  requestAnimationFrame(AW.app.raf);
};

/* ----------------------------------------------------------- frame graph */

const ctx = {
  gl: null, cam: null, rt: null, res: [0, 0],
  time: 0, dt: 0, view: 'main', quality: 2, settings: null, loaded: false,
};

const CLIP_OFF = [0, 0, 0, 1e9];
const CLIP_REFLECT = [0, 1, 0, 0];

function runPasses(phase, view) {
  const list = AW.passes.active(phase, view);
  AW.app.stats.passes = list.length;
  for (let i = 0; i < list.length; i++) {
    const d = list[i];
    AW.gl.baseline();
    ctx.view = view;
    AW.try('pass:' + d.name, () => d.run(ctx));
  }
}

AW.app.simulate = function (dt) {
  const s = AW.settings;
  AW.app.frameCount++;
  AW.app.stats.sims = 0;

  const u = AW.uniforms;
  u.uFrame = AW.app.frameCount;
  u.uRealTime = AW.app.realTime;

  if (!s.paused) {
    AW.app.simTime += dt;
    s.timeOfDay = (s.timeOfDay + (dt / 60) * s.timeScale) % 24;
    if (s.timeOfDay < 0) s.timeOfDay += 24;
  }
  u.uTime = AW.app.simTime;
  u.uSeed = s.seed;

  AW.cam.tick(dt);
  updateEnvironment();

  ctx.gl = AW.gl; ctx.cam = AW.cam; ctx.rt = AW._rts;
  ctx.time = AW.app.simTime; ctx.dt = dt;
  ctx.quality = s.quality; ctx.settings = s; ctx.res = AW.app.res;

  for (const d of AW.sims.sorted()) {
    if (d.enabled && d.enabled() === false) continue;
    AW.app.stats.sims++;
    AW.try('sim:' + d.name, () => d.update(dt, ctx));
  }
};

AW.app.render = function () {
  const s = AW.settings;
  const g = AW.gl;
  const rt = AW._rts;
  if (!rt.scene) return;
  bindTargetUniforms();

  AW.app.prevViewProj.set(AW.app.lastMainViewProj);
  AW.uniforms.uPrevViewProj = AW.app.prevViewProj;

  // --- scene, reflected. Skipped when the eye is under the surface: a mirror
  // image through the sea plane is meaningless from below and the water pass
  // does not sample it in that state.
  if (!AW.cam.underwater) {
    AW.cam.computeMatrices(AW.app.aspect, 'reflect');
    AW.uniforms.uClipPlane = CLIP_REFLECT;
    AW.gl.frontFace('cw');
    const target = rt.reflect;
    target.clear(0, 0, 0, 1);
    ctx.res = [target.w, target.h];
    runPasses('scene', 'reflect');
    target.resolve();
  }

  // --- scene, real.
  AW.cam.computeMatrices(AW.app.aspect, 'main');
  AW.uniforms.uClipPlane = CLIP_OFF;
  AW.uniforms.uUnderwater = AW.cam.underwater ? 1 : 0;
  AW.gl.frontFace('ccw');
  const scene = rt.scene;
  scene.clear(0, 0, 0, 1);
  ctx.res = [scene.w, scene.h];
  runPasses('scene', 'main');
  scene.resolve();
  AW.app.lastMainViewProj.set(AW.cam.viewProj);

  // --- post. The app binds `ldr` before each pass so a single-target pass
  // needs to do nothing, while a pass with its own targets just rebinds.
  ctx.res = [rt.ldr.w, rt.ldr.h];
  rt.ldr.clear(0, 0, 0, 1);
  const post = AW.passes.active('post', 'main');
  AW.app.stats.passes += post.length;
  for (const d of post) {
    AW.gl.baseline();
    rt.ldr.bind();
    ctx.view = 'main';
    AW.try('pass:' + d.name, () => d.run(ctx));
  }

  // --- present. A straight copy: the composite pass already tonemapped and
  // encoded to sRGB, so anything more here would double-apply.
  g.screen();
  g.baseline();
  g.depthTest(false);
  g.depthWrite(false);
  g.blend('none');
  const b = AW.gl.program('_blit', { vs: ['awVsCommon'], fs: ['fsBlit'] });
  b.u.uSource = rt.ldr.tex;   // must precede use(): use() is what uploads
  b.use();
  g.drawFullscreen();
};

AW.app.step = function (dt, opts) {
  const o = opts || {};
  if (!AW.settings.paused) AW.app.realTime += dt;
  AW.app.simulate(dt);
  if (o.render !== false) AW.app.render();
  if (!AW.app.ready) AW.markReady();
};

AW.app.raf = function (now) {
  const t = now || AW.now();
  const last = AW.app._lastT || t;
  let dt = (t - last) / 1000;
  AW.app._lastT = t;
  // A tab that was hidden for a minute must not teleport the simulation.
  dt = clamp(dt, 0.0005, 0.05);

  AW.app.resize();
  AW.try('frame', () => AW.app.step(dt));

  const ms = AW.now() - t;
  const st = AW.app.stats;
  st.cpu = st.cpu * 0.9 + ms * 0.1;
  st.fps = st.fps ? st.fps * 0.94 + (1 / dt) * 0.06 : 1 / dt;
  st.ms = 1000 / (st.fps || 1);

  AW.input.endFrame();
  if (!AW.gl.isLost) requestAnimationFrame(AW.app.raf);
};

/* ------------------------------------------------------------ snapshots */

/**
 * Put the world into a known, populated, reproducible state and draw it.
 * This is the only supported way to take a screenshot: a freshly loaded page
 * has settled nothing, so it would show an empty ocean and no wildlife.
 *
 *   AW.snap(6.2)                                  // dawn
 *   AW.snap(13, { cameraMode: 'dive' })            // under the surface
 *   AW.snap(21, { settings: { windSpeed: 26 }, cam: { pos: [0, 3, 60] } })
 */
AW.snap = function (hours, opts) {
  const o = opts || {};
  // A snapshot must not depend on what ran before it. Without this reset a
  // second snap in the same session inherits the first one's weather and
  // camera, so every comparison is really a comparison of two scenarios and
  // the diff shows history rather than the change under test.
  Object.assign(AW.settings, AW.settingsDefaults);
  AW.reviseSettings();
  // A sim opts into reproducibility by exposing reset(), which returns its
  // state to the canonical start. Without it a second snap in the same session
  // settles an already-settled world, so creatures sit somewhere new and two
  // "identical" snapshots differ. Modules that own no persistent state can
  // omit it; the hook is optional by design.
  for (const d of AW.sims.list()) {
    if (typeof d.reset === 'function') AW.try('sim.reset:' + d.name, () => d.reset());
  }

  if (hours !== undefined && hours !== null) AW.settings.timeOfDay = ((hours % 24) + 24) % 24;
  if (o.settings) Object.assign(AW.settings, o.settings);
  // `mode` is the documented spelling; `cameraMode` is accepted so existing
  // scripts keep working.
  if (o.mode) AW.settings.cameraMode = o.mode;
  if (o.cameraMode) AW.settings.cameraMode = o.cameraMode;
  if (o.cam) {
    if (o.cam.pos) AW.v3.copy(AW.cam.pos, o.cam.pos);
    if (o.cam.yaw !== undefined) AW.cam.yaw = o.cam.yaw;
    if (o.cam.pitch !== undefined) AW.cam.pitch = o.cam.pitch;
    if (o.cam.fov !== undefined) AW.cam.fov = o.cam.fov * DEG;
    if (o.cam.roll !== undefined) AW.cam.roll = o.cam.roll;
  } else {
    // A canonical opening pose, so two snaps of the same scenario frame the
    // same water. The camera controllers would otherwise leave the eye
    // wherever the last caller parked it.
    //
    // This is the shelf at 1.26 km south-west of the origin looking back across
    // the basin — the same pose bootstrap opens on. It is deliberately not the
    // origin: a 120 m pit sits there, so the default framing would be nothing
    // but deep blue and every verification frame would under-represent the
    // water. Keep the two in step.
    AW.v3.set(AW.cam.pos, -890, 6.5, -890);
    AW.cam.yaw = 3.677;
    AW.cam.pitch = -0.05;
    AW.cam.roll = 0;
    AW.cam.speed = 12;
  }

  const dt = 1 / 60;
  const steps = o.steps === undefined ? 260 : o.steps;
  const warm = o.renderSteps === undefined ? 2 : o.renderSteps;

  AW.cam.tick(dt);
  for (let i = 0; i < steps; i++) AW.app.simulate(dt);

  // Freeze the wave clock so two runs of the same snapshot are pixel-comparable.
  AW.app.simTime = o.t === undefined ? 12 : o.t;
  AW.uniforms.uTime = AW.app.simTime;

  for (let i = 0; i < warm; i++) {
    // Pin the frame counter so per-frame dither and jitter — which every
    // raymarcher wants — land on the same values on every run. Without this
    // two snapshots of "the same" moment differ across most of the water, and
    // a before/after comparison shows the noise, not the change.
    AW.app.frameCount = 4096;
    AW.app.simulate(0);
    AW.app.render();
  }
  AW.markReady();

  const p = AW.cam.pos;
  return `snap t=${AW.settings.timeOfDay.toFixed(2)} mode=${AW.settings.cameraMode} `
    + `pos=[${p[0].toFixed(0)},${p[1].toFixed(0)},${p[2].toFixed(0)}] `
    + `under=${AW.cam.underwater} renders=${AW.app.frameCount} errors=${AW.app.errors.length}`;
};

/* ----------------------------------------------------------------- start */

AW.app.simTime = 0;
AW.app.realTime = 0;
AW.app.frameCount = 0;
AW.app.aspect = 16 / 9;
AW.app.res = [1600, 900];

if (typeof document !== 'undefined') {
  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', () => AW.try('boot', AW.app.boot));
  } else {
    AW.try('boot', AW.app.boot);
  }
}