Stacked transparent glass renders as solid slabs

• A single pane looks correct, but two panes front to back make the rear one invisible or swap order as the camera rotates.
• Interior columns and furniture behind the glazing never appear.
• A glass box made of many faces shows some faces missing and some stacking a darker colour.

1. Set depthWrite: false on the glass material and see whether the rear surface appears.
2. Temporarily set transparent: false and opacity 1 to confirm geometry and winding.
3. Try side: THREE.DoubleSide to rule out back-face culling.
4. Check whether the glass is one mesh with many faces, which per-object sorting cannot order.

Use MeshPhysicalMaterial with depthWrite: false, side: THREE.DoubleSide, transmission 0.6 and renderOrder 10, or assign renderOrder 100 - i per layer so distant panes draw first; use alphaTest 0.5 with transparent: false for cut-out foliage.

var glassMat = new THREE.MeshPhysicalMaterial({
  color: 0x9fc6e8,
  transparent: true,
  opacity: 0.35,
  roughness: 0.1,
  metalness: 0,
  depthWrite: false,        // 关键
  side: THREE.DoubleSide,
  transmission: 0.6
});
glassMat.renderOrder = 10;   // 数值大的后画

glassLayers.forEach(function (mesh, i) {
  mesh.material.depthWrite = false;
  mesh.renderOrder = 100 - i;   // 远景先画
});

• Turning transparent off to remove the sorting artifact makes the glass fully opaque and hides the interior.
• Keeping depthWrite: true and only lowering opacity still culls the rear panes in the depth test.