TypeError: attribute.value.slice is not a function

CesiumJS
1

I am trying to load a tileset that contains a .glb, that utilizes “Sparse Accessors” and “EXT_mesh_features”. 3D tiles are served via Cesium-ion. I think there is a bug in CesiumJS. Here is the error I am getting:

TypeError: attribute.value.slice is not a function
    at addAttribute (http://localhost:4200/projects_stac_src_app_pages_explorer-3d_explorer-3d_module_ts.js:194881:39)
    at new VertexArray (http://localhost:4200/projects_stac_src_app_pages_explorer-3d_explorer-3d_module_ts.js:195079:5)
    at buildDrawCommand (http://localhost:4200/projects_stac_src_app_pages_explorer-3d_explorer-3d_module_ts.js:284191:23)
    at push.46753.ModelSceneGraph.buildDrawCommands (http://localhost:4200/projects_stac_src_app_pages_explorer-3d_explorer-3d_module_ts.js:278861:92)
    at buildDrawCommands (http://localhost:4200/projects_stac_src_app_pages_explorer-3d_explorer-3d_module_ts.js:272526:23)
    at push.86789.Model.update (http://localhost:4200/projects_stac_src_app_pages_explorer-3d_explorer-3d_module_ts.js:272341:3)
    at push.5985.Model3DTileContent.update (http://localhost:4200/projects_stac_src_app_pages_explorer-3d_explorer-3d_module_ts.js:273673:9)
    at push.34426.Cesium3DTile.process (http://localhost:4200/projects_stac_src_app_pages_explorer-3d_explorer-3d_module_ts.js:211306:19)
    at processTiles (http://localhost:4200/projects_stac_src_app_pages_explorer-3d_explorer-3d_module_ts.js:218218:12)
    at push.11992.Cesium3DTileset.prePassesUpdate (http://localhost:4200/projects_stac_src_app_pages_explorer-3d_explorer-3d_module_ts.js:218045:3)

Did some digging into the stack trace, here’s what I found out:

image
image294×195 3.39 KB

The value of the attribute is 0.

image
image780×166 6.8 KB

hasValue is true.

image
image1389×234 9.49 KB

it crashes here. It assumes that the value should be an array.

Here is the buffer view and the accessor:

  "bufferViews": [
    {
      "buffer": 0,
      "byteOffset": 0,
      "byteLength": 640800,
      "byteStride": 32,
      "target": 34962
    },
    {
      "buffer": 0,
      "byteOffset": 640800,
      "byteLength": 40052,
      "target": 34963
    },
    {
      "buffer": 0,
      "byteOffset": 680852,
      "byteLength": 140700
    },
    {
      "buffer": 0,
      "byteOffset": 821552,
      "byteLength": 140700
    }
  ],
"accessors": [
..........
   {
      "type": "SCALAR",
      "componentType": 5123,
      "count": 20025,
      "sparse": {
        "count": 2,
        "indices": {
          "bufferView": 2,
          "byteOffset": 140696,
          "componentType": 5123
        },
        "values": {
          "bufferView": 3,
          "byteOffset": 140696
        }
      }
    }
]
2

Sparse accessors are currently not supported. This is tracked in Support sparse accessors in Model · Issue #10284 · CesiumGS/cesium · GitHub . (And I think that it should be fixed ASAP, but cannot say what the priorities and timeline are for this one…)