[claude] InstancedMesh for glass tiles and island spires (#425) (#443)

Co-authored-by: Claude (Opus 4.6) <claude@hermes.local>
Co-committed-by: Claude (Opus 4.6) <claude@hermes.local>

app.js

@@ -295,29 +295,43 @@ const tileEdgeGeo = new THREE.EdgesGeometry(tileGeo);
 /** @type {Array<{mat: THREE.LineBasicMaterial, distFromCenter: number}>} */
 const glassEdgeMaterials = [];
 
+// Pre-collect valid tile positions so we know the InstancedMesh count upfront
+const _tileDummy = new THREE.Object3D();
+/** @type {Array<{x: number, z: number, distFromCenter: number}>} */
+const _tileSlots = [];
 for (let row = -5; row <= 5; row++) {
   for (let col = -5; col <= 5; col++) {
     const x = col * GLASS_TILE_STEP;
     const z = row * GLASS_TILE_STEP;
     const distFromCenter = Math.sqrt(x * x + z * z);
     if (distFromCenter > GLASS_RADIUS) continue;
-
-    // Transparent glass tile
-    const tile = new THREE.Mesh(tileGeo, glassTileMat.clone());
-    tile.rotation.x = -Math.PI / 2;
-    tile.position.set(x, 0, z);
-    glassPlatformGroup.add(tile);
-
-    // Glowing edge lines
-    const mat = glassEdgeBaseMat.clone();
-    const edges = new THREE.LineSegments(tileEdgeGeo, mat);
-    edges.rotation.x = -Math.PI / 2;
-    edges.position.set(x, 0.002, z);
-    glassPlatformGroup.add(edges);
-    glassEdgeMaterials.push({ mat, distFromCenter });
+    _tileSlots.push({ x, z, distFromCenter });
   }
 }
 
+// Transparent glass tiles — InstancedMesh: all tiles rendered in one draw call
+const glassTileIM = new THREE.InstancedMesh(tileGeo, glassTileMat, _tileSlots.length);
+glassTileIM.instanceMatrix.setUsage(THREE.StaticDrawUsage);
+_tileDummy.rotation.x = -Math.PI / 2;
+for (let i = 0; i < _tileSlots.length; i++) {
+  const { x, z } = _tileSlots[i];
+  _tileDummy.position.set(x, 0, z);
+  _tileDummy.updateMatrix();
+  glassTileIM.setMatrixAt(i, _tileDummy.matrix);
+}
+glassTileIM.instanceMatrix.needsUpdate = true;
+glassPlatformGroup.add(glassTileIM);
+
+// Glowing edge lines — individual LineSegments retained for per-distance opacity animation
+for (const { x, z, distFromCenter } of _tileSlots) {
+  const mat = glassEdgeBaseMat.clone();
+  const edges = new THREE.LineSegments(tileEdgeGeo, mat);
+  edges.rotation.x = -Math.PI / 2;
+  edges.position.set(x, 0.002, z);
+  glassPlatformGroup.add(edges);
+  glassEdgeMaterials.push({ mat, distFromCenter });
+}
+
 // Void shimmer — faint point light below the glass, emphasising the infinite depth
 const voidLight = new THREE.PointLight(NEXUS.colors.accent, 0.5, 14);
 voidLight.position.set(0, -3.5, 0);
@@ -491,8 +505,12 @@ const perlin = createPerlinNoise();
   });
 
   const CRYSTAL_MIN_H = 2.05; // only spawn on high terrain
-  const crystalGroup = new THREE.Group();
 
+  // --- Crystal spire formations (InstancedMesh) ---
+  // Two-pass: collect params first so we know the count, then build InstancedMesh.
+  // Unit cone (r=1, h=1) scaled per-instance replaces N unique ConeGeometry objects.
+  /** @type {Array<{sx:number,sz:number,posY:number,rotX:number,rotZ:number,scaleXZ:number,scaleY:number}>} */
+  const _spireData = [];
   for (let row = -5; row <= 5; row++) {
     for (let col = -5; col <= 5; col++) {
       const bx = col * 1.75, bz = row * 1.75;
@@ -518,18 +536,36 @@ const perlin = createPerlinNoise();
         const spireScale = 0.14 + (candidateH - CRYSTAL_MIN_H) * 0.11;
         const spireH = spireScale * (0.8 + Math.abs(perlin(sx, sz)) * 0.45);
         const spireR = spireH * 0.17;
-
-        const spireGeo = new THREE.ConeGeometry(spireR, spireH * 2.8, 5);
-        const spire = new THREE.Mesh(spireGeo, crystalMat);
-        spire.position.set(sx, candidateH + spireH * 0.5, sz);
-        spire.rotation.z = perlin(sx * 2, sz * 2) * 0.28;
-        spire.rotation.x = perlin(sx * 3 + 1, sz * 3 + 1) * 0.18;
-        spire.castShadow = true;
-        crystalGroup.add(spire);
+        _spireData.push({
+          sx, sz,
+          posY: candidateH + spireH * 0.5,
+          rotX: perlin(sx * 3 + 1, sz * 3 + 1) * 0.18,
+          rotZ: perlin(sx * 2, sz * 2) * 0.28,
+          scaleXZ: spireR,
+          scaleY: spireH * 2.8,
+        });
       }
     }
   }
 
+  // Single InstancedMesh: N spires rendered in one draw call
+  const _spireDummy = new THREE.Object3D();
+  const spireBaseGeo = new THREE.ConeGeometry(1, 1, 5);
+  const crystalGroup = new THREE.Group();
+  const spireIM = new THREE.InstancedMesh(spireBaseGeo, crystalMat, _spireData.length);
+  spireIM.castShadow = true;
+  spireIM.instanceMatrix.setUsage(THREE.StaticDrawUsage);
+  for (let i = 0; i < _spireData.length; i++) {
+    const { sx, sz, posY, rotX, rotZ, scaleXZ, scaleY } = _spireData[i];
+    _spireDummy.position.set(sx, posY, sz);
+    _spireDummy.rotation.set(rotX, 0, rotZ);
+    _spireDummy.scale.set(scaleXZ, scaleY, scaleXZ);
+    _spireDummy.updateMatrix();
+    spireIM.setMatrixAt(i, _spireDummy.matrix);
+  }
+  spireIM.instanceMatrix.needsUpdate = true;
+  crystalGroup.add(spireIM);
+
   // --- Noise-displaced rocky underside with stalactite drips ---
   // CylinderGeometry with open top (openEnded=true) so only the tapered side
   // wall is visible. Vertices are radially and vertically displaced by Perlin