glTF2.0 in UE5.2, metadata "EXT_structural_metadata", "EXT_mesh_features"

[m.kwiatkowski]

@Marco13 Thx. But now I know How injected metadata to own buildings:
here is my example:

budynki.zip (217.5 KB)

1. I create buildings in Blender with _FEATURE_ID_0:
   

   

2. Connect vertexes to _FEATURE_ID_0
   

   

3. Export gltTF with attribute table:
   

4. Create own binary file with metadata:
   

   

Form me cesium#estimatedHeight :

FLOAT32 big-endian hexa 0x00002041 = 10
FLOAT32 big-endian hexa 0x0000F041 = 30
FLOAT32 big-endian hexa 0x00004842 = 50

elemetID:

INT32 hexa 0x00000000 = 0
INT32 hexa 0x01000000 = 1
INT32 hexa 0x02000000 = 2

4. Connect metadata file to glt:

    "buffers":[
        {
            "byteLength":3384,
            "uri":"budynki.bin"
        },
        {
          "name": "bufferMeta",
          "byteLength": 24,
          "uri": "bufferMeta.bin"
        }
    ],

5. Create bufferViews with metadata:

    "bufferViews":[
        {
          ...
        },
        {
          "buffer": 1,
          "byteLength": 12,
          "byteOffset": 0
        },
        {
          "buffer": 1,
          "byteLength": 12,
          "byteOffset": 12
        }
    ],

6. add accessors with metadata:

    "accessors":[
        {
          ..
        },
        {
            "bufferView":6,
            "componentType":5126,
            "count":12,
            "type":"SCALAR",
            "max":[
                50
            ],
            "min":[
                10
            ]
        },
        {
            "bufferView":7,
            "componentType":5125,
            "count":12,
            "type":"SCALAR",
            "max":[
                2
            ],
            "min":[
                0
            ]
        }
    ],

7. connect to mesh:

    "meshes":[
        {
            "name":"Cube.003",
            "primitives":[
                {
                    "attributes":{
                        "_FEATURE_ID_0":0,
                        "COLOR_0":1,
                        "POSITION":2,
                        "NORMAL":3,
                        "TEXCOORD_0":4
                    },
                    "indices":5,
                    "material":0,
                    "extensions": {
                      "EXT_feature_metadata": {
                        "featureIdAttributes": [
                          {
                            "featureTable": "default",
                            "featureIds": {
                              "attribute": "_FEATURE_ID_0"
                            }
                          },
                          {
                            "featureTable": "default",
                            "featureIds": {
                              "constant": 0,
                              "divisor": 2
                            }
                          }
                        ]
                      }
                    }
                }
            ]
        }
    ],

8. Add class:

      "extensionsUsed": [
        "EXT_feature_metadata"
      ],
      "extensionsRequired": [
        "EXT_feature_metadata"
      ],
      "extensions": {
        "EXT_feature_metadata": {
          "schema": {
            "classes": {
              "default": {
                "properties": {
                  "cesium#estimatedHeight": {
                    "type": "FLOAT32",
                    "default": 0.0
                  },
                  "elementId": {
                    "type": "INT32"
                  },
                  "year": {
                    "type": "STRING",
                    "optional": true,
                    "default": "2022"
                  }
                }
              }
            }
          },
          "featureTables": {
            "default": {
              "class": "default",
              "count": 3,
              "properties": {
                "cesium#estimatedHeight": {
                  "bufferView": 6
                },
                "elementId": {
                  "bufferView": 7
                }
              }
            }
          }
        }
      }

All works finie in UE.

This example change tekstur when heigh is 30:

But now I need write python script to Blender and automate this process. And I need to know how to use EXT_mesh_gpu_instancing