feat: refine exploration presentation and audio flow

src/game/data/campSoundscapes.ts

@@ -1,4 +1,8 @@
-import type { AmbienceTrackKey, MusicTrackKey } from '../audio/audioAssets';
+import {
+  musicTrackIntegratedLoudnessLufs,
+  type AmbienceTrackKey,
+  type MusicTrackKey
+} from '../audio/audioAssets';
 import type { CampSkinId } from './campSkins';
 
 export type CampMusicGroupId = 'rally' | 'wayfarer' | 'grand-strategy' | 'frontier';
@@ -117,3 +121,41 @@ export function getCampSoundscape(skinId: CampSkinId): CampSoundscape {
     ambience: campAmbienceDefinitions[mapping.ambienceId]
   };
 }
+
+export function campMusicVolumeForTrackKey(
+  trackKey: string,
+  fallbackVolume = 0.2
+) {
+  return Object.values(campMusicGroups).find(
+    (definition) => definition.trackKey === trackKey
+  )?.volume ?? fallbackVolume;
+}
+
+export function musicVolumeMatchedToCampTrack(
+  trackKey: MusicTrackKey,
+  referenceTrackKey: CampMusicTrackKey = 'camp-rally',
+  fallbackVolume = campMusicVolumeForTrackKey(referenceTrackKey)
+) {
+  const trackLoudness = musicTrackIntegratedLoudnessLufs[trackKey];
+  const referenceLoudness =
+    musicTrackIntegratedLoudnessLufs[referenceTrackKey];
+  const referenceVolume = campMusicVolumeForTrackKey(
+    referenceTrackKey,
+    fallbackVolume
+  );
+  if (
+    !Number.isFinite(trackLoudness) ||
+    !Number.isFinite(referenceLoudness) ||
+    !Number.isFinite(referenceVolume) ||
+    referenceVolume <= 0
+  ) {
+    return fallbackVolume;
+  }
+
+  const matchedVolume =
+    referenceVolume *
+    10 ** ((referenceLoudness - trackLoudness) / 20);
+  return Math.round(
+    Math.min(1, Math.max(0.01, matchedVolume)) * 1000
+  ) / 1000;
+}