         let wireframeMesh;
          let textMesh;

          // this is a mesh we've seen before
          if (allMeshes.has(mesh)) {
            // may have been updated:
            const meshContext = allMeshes.get(mesh);
            meshMesh = meshContext.mesh;
            wireframeMesh = meshContext.wireframe;

            if (meshContext.timestamp < mesh.lastChangedTime) {
              // the mesh was updated!
              meshContext.timestamp = mesh.lastChangedTime;

              const geometry