GlowLayer doubles the number of active faces

Questions
1
2

It is expected as it draws everything twice, so twice the faces.

3

Got it, it seems that when using the GlowLayer, i need to control which meshes need to be addIncludedOnlyMesh

4

yes but be careful to also add any blockers within the layer, not only the glowing meshes should be in, but also the things hiding the glow.

5 
   const oldMesh = this._glowLayer.hasMesh;

      this._glowLayer.hasMesh = (mesh: Mesh) => {
        const status = oldMesh.apply(this._glowLayer, mesh);
        if (!status) return status;

        const materials: Material[] = [];
        if (mesh.material instanceof MultiMaterial) {
          materials.push(...mesh.material.getChildren());
        } else {
          materials.push(mesh.material);
        }

        for (const mtl of materials) {
          if ("emissiveColor" in mtl) {
            const color = mtl.emissiveColor as Color3;
            if (!color.equals(Color3.Black())) {
              return true;
            }
          }
          if (mtl["emmissiveTexture"]) {
            return true;
          }
        }

        return false;
      };
    }

Whether to provide an injection function to determine whether the grid is allowed to emit light