fix: replace Box3 auto-scale with measured modelLength per species

- Remove unreliable Box3.setFromObject scaling (broke for skinned meshes,
  control rigs, and scene-containing GLBs)
- Use measured vertex extents (scripts/measure-models.mjs) as modelLength
- Clownfish: hide Surface/TopLight/Bubbles/Mirrored nodes (GLB is a full
  scene, not just a fish) — eliminates the white box + giant fish bug
- All 10 species now have accurate scale factors

src/main.ts

@@ -60,39 +60,40 @@ function getSpeciesUrl(sp: FishSpecies): string {
   };
   return urls[sp];
 }
-// Per-species correction factor between Box3.setFromObject's measured extent
-// and the model's true rendered extent (see FishSpec.baseScale). Box3 measures
-// skinned geometry in skeleton space (and may use a stale cached bounding box),
-// which does not match the GPU's actual output (mesh.matrixWorld * skinning *
-// position). baseScale = rendered / box3, so `targetLength / (box3 * baseScale)`
-// normalizes each fish to its real rendered size.
-//
-// Measured with three.js's exact skinning formula per GLB. Most models are 1.0.
-// The skinned blendswap oscar/knifefish deviate and are corrected here. The
-// clownfish GLB is a full *scene* (water "Surface" 45.3, "TopLight" 15, "Bubbles"
-// 3.4) plus a small skinned body (~8.3); box3 is dominated by the water plane, so
-// a baseScale can't fix it without blowing up the scene geometry — left at 1.0
-// until the GLB is re-exported as a clean fish.
-const SPECIES_SCALE: Record<FishSpecies, number> = {
-  angelfish: 1.0,
-  goldfish: 1.0,
-  guppy: 1.0,
-  betta: 1.0,
-  blue_tang: 1.0,
-  flower_horn: 1.0,
-  neon_tetra: 1.0,
-  oscar: 1.35,
-  knifefish: 2.58,
-  clownfish: 1.0,
+// Per-species true longest rendered extent (model units), measured
+// offline with scripts/measure-models.mjs (stride-safe rest-pose +
+// swim-clip evaluation of the actual GLB data). Fish are scaled by
+// targetLength / modelLength. This replaces the old
+// Box3.setFromObject auto-measure, which under-reports armature-scaled
+// models (oscar, knifefish) and for the clownfish is dominated by its
+// 45.3-unit water plane (see FishSpec.modelLength).
+const SPECIES_LENGTH: Record<FishSpecies, number> = {
+  angelfish: 4.2139,
+  goldfish: 1.7386,
+  guppy: 2.8070,
+  betta: 1.0228,
+  blue_tang: 1.0192,
+  flower_horn: 1.0516,
+  neon_tetra: 3.6548,
+  oscar: 8.8411,
+  knifefish: 23.0140,
+  clownfish: 8.2773,
 };
+// The clownfish GLB bundles a whole aquarium scene: an untextured white
+// "Surface" water plane (45.3 units — the "white box"), a "TopLight"
+// emissive slab, a "Bubbles" prop, and "Original-Mirrored", a mirrored
+// duplicate of the body that overlaps the real "ClownFish" node. Hide
+// everything except the fish itself.
+const HIDDEN_CLOWNFISH_NODES = ["Surface", "TopLight", "Bubbles", "Original-Mirrored"];
 function fishToSpec(f: FishData): FishSpec {
   return {
     url: getSpeciesUrl(f.species),
     targetLength: f.genetics.sizeMult * 0.5,
+    modelLength: SPECIES_LENGTH[f.species],
     speed: [0.3 * f.genetics.speedMult, 0.7 * f.genetics.speedMult],
     orient: isQuaternius(f.species) ? { y: Math.PI / 2 } : undefined,
     genetics: f.genetics,
-    baseScale: SPECIES_SCALE[f.species],
+    hideNodes: f.species === "clownfish" ? HIDDEN_CLOWNFISH_NODES : undefined,
   };
 }