{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "featureId.schema.json",
  "title": "Feature ID in EXT_instance_features",
  "type": "object",
  "description": "Feature IDs stored in a GPU mesh instancing attribute",
  "allOf": [
    {
      "$ref": "glTFProperty.schema.json"
    }
  ],
  "properties": {
    "featureCount": {
      "type": "integer",
      "minimum": 1,
      "description": "The number of unique features in the attribute."
    },
    "nullFeatureId": {
      "type": "integer",
      "minimum": 0,
      "description": "A value that indicates that no feature is associated with this instance."
    },
    "label": {
      "type": "string",
      "pattern": "^[a-zA-Z_][a-zA-Z0-9_]*$",
      "description": "A label assigned to this feature ID set. Labels must be alphanumeric identifiers matching the regular expression `^[a-zA-Z_][a-zA-Z0-9_]*$`."
    },
    "attribute": {
      "description": "An attribute containing feature IDs. When this is omitted, then the feature IDs are assigned to the GPU instances by their index.",
      "$ref": "featureIdAttribute.schema.json"
    },
    "propertyTable": {
      "type": "integer",
      "minimum": 0,
      "description": "The index of the property table containing per-feature property values. Only applicable when using the `EXT_structural_metadata` extension."
    },
    "extensions": {},
    "extras": {}
  },
  "required": [
    "featureCount"
  ]
}