xeokit Streaming Loader

Batch-loads multi-part models from a JSON manifest into a SceneModel and an optional DataModel, chunk by chunk.

Large BIM and CAD models routinely exceed any sensible single-file limit — splitting them into geometry chunks (typically XGF) plus matching semantic chunks (DataModel JSON) is the standard delivery shape. ModelChunksLoader walks a manifest of those chunks and applies the configured per-chunk loaders, populating one SceneModel + DataModel pair end-to-end with no caller-side orchestration.

Shape

classDiagram
    direction TB
    class ModelChunksLoader {
      +sceneModelLoader : ModelLoader
      +dataModelLoader? : ModelLoader
      +load(params)
    }
    class ModelChunksLoaderParams {
      +sceneModelLoader : ModelLoader
      +dataModelLoader? : ModelLoader
    }
    class ModelChunksManifestParams {
      +sceneModelMIMEType : string
      +sceneModelFiles    : string[]
      +dataModelFiles?    : string[]
    }
    class LoadModelChunksParams {
      +modelChunksManifest : ModelChunksManifestParams
      +baseDir             : string
      +sceneModel          : SceneModel
      +dataModel?          : DataModel
    }
    class SceneModel {
      <<scene>>
    }
    class DataModel {
      <<data>>
    }
    ModelChunksLoader ..> ModelChunksLoaderParams : constructor
    ModelChunksLoader ..> LoadModelChunksParams : load
    LoadModelChunksParams o-- ModelChunksManifestParams
    LoadModelChunksParams o-- SceneModel : writes
    LoadModelChunksParams o-- DataModel : writes

Manifest shape

The manifest is a small JSON file pairing geometry chunks with the matching semantic chunks:

{
    "sceneModelMIMEType": "arraybuffer",
    "sceneModelFiles": [
        "model.xgf",
        "model2.xgf",
        "model3.xgf"
    ],
    "dataModelFiles": [
        "model.json",
        "model2.json",
        "model3.json"
    ]
}
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• sceneModelFiles lists the geometry chunks (XGF, glTF, …).
• dataModelFiles (optional) lists matching DataModel JSON chunks.
• sceneModelMIMEType chooses how chunks are fetched ("arraybuffer" for binary, "json" for text).

Features

• One call loads the whole model — pass the manifest, the baseDir, the target SceneModel + DataModel, and the loader walks every chunk in parallel.
• Pluggable per-chunk loaders — pass an formats!XGFLoader | XGFLoader for geometry, DataModelImporter for semantics, or any other loader that implements ModelLoader.
• Geometry + semantics in lockstep — chunks share an ordering so the loader emits SceneObjects and DataObjects with matching ids; picking and inspection see one coherent graph at the end.
• Returns when everything's done — single Promise resolution when every chunk has reached its target model.

Installation

npm install @xeokit/sdk
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Quick Start

1) Import the entry point

import { ModelChunksLoader } from "@xeokit/sdk/model/streaming";
import { XGFLoader }         from "@xeokit/sdk/formats/xgf";
import { DataModelImporter } from "@xeokit/sdk/formats/datamodel";
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2) Construct with per-chunk loaders

const modelChunksLoader = new ModelChunksLoader({
  sceneModelLoader: new XGFLoader(),
  dataModelLoader:  new DataModelImporter()
});
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3) Load a manifest

const manifest = await fetch("modelChunksManifest.json").then(r => r.json());

await modelChunksLoader.load({
  modelChunksManifest: manifest,
  baseDir: ".",
  sceneModel,
  dataModel
});
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