SceneModelParams (xeokit JSON) Loader / Exporter

SceneModelImporter reads a SceneModelParams JSON document into a SceneModel, and SceneModelExporter writes a SceneModel back out as SceneModelParams.

SceneModelParams is the SDK's canonical JSON representation of a SceneModel — the same param object accepted by Scene.createModel and produced by SceneModel.toParams. This module is the thin loader/exporter wrapper that plugs that representation into the common ModelLoader / ModelExporter pipeline, so it lives alongside the binary format adapters (FBX, RVM, XGF, …) and is driven the same way.

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1. The format

SceneModelParams is a plain JSON object — no binary container, no quantisation pass of its own. It captures a SceneModel's complete renderable state:

• id, coordinateSystem (origin / scale / basis), and the model placement (matrix / position / scale / quaternion).
• Geometries — both uncompressed (SceneGeometryParams) and already-compressed (SceneGeometryCompressedParams) buffers.
• Meshes, objects, transforms, materials, and textures.

Because it mirrors the SceneModel's own param surface, a round-trip is lossless: object ids, geometry ids, transforms, and coordinate-system settings survive export → import unchanged, with no re-tessellation or re-quantisation. That makes it useful as a cache payload, a test fixture, or a hand-inspectable debug dump.

The document carries an optional version field. It is absent in hand-written documents and defaults to "1.0"; the loader keys its parser table on it.

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2. Load / export pipeline

Both sides are deliberately thin — the real work lives on SceneModel:

   SceneModelParams (JSON object)
        │
        ▼
   versions/1_0/parse.ts
        │   sceneModel.fromParams(fileData)
        ▼
   SceneModel populated


   SceneModel
        │
        ▼
   versions/1_0/encode.ts
        │   sceneModel.toParams()  →  SceneModelParams
        ▼
   SceneModelParams (JSON object)
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• Loader (SceneModelImporter) — format: "SceneModelParams", fileDataType: "json". getVersion reads fileData.version (falling back to "1.0") and dispatches to the matching parser. The "1.0" parser delegates straight to SceneModel.fromParams.
• Exporter (SceneModelExporter) — same format, same fileDataType, defaultVersion: "1.0". The "1.0" encoder calls SceneModel.toParams and resolves the resulting SceneModelParams object. Encoding yields cooperatively to the host (yieldToHost) so a large model doesn't block the main thread.

fileData here is the parsed JSON object, not a string — read the .json with JSON.parse (or response.json()) before handing it to the loader, and JSON.stringify the exporter's result before persisting it.

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3. Usage

Loader

import {Scene} from "@xeokit/sdk/model/scene";
import {SceneModelImporter} from "@xeokit/sdk/scenemodel";

const scene = new Scene();
const sceneModel = scene.createModel({id: "myModel"}).value;

const fileData = await (await fetch("model.json")).json();

await new SceneModelImporter().load({fileData, sceneModel});
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Exporter

import {SceneModelExporter} from "@xeokit/sdk/scenemodel";

const sceneModelParams = await new SceneModelExporter().write({sceneModel});
const json = JSON.stringify(sceneModelParams);
// persist or transmit `json`
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The exporter resolves the SceneModelParams object itself; stringify it yourself when you need bytes on disk or over the wire.

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4. File map

formats/scenemodel/
├── README.md                     (this file)
├── SceneModelImporter.ts     ModelLoader subclass — entry point
├── SceneModelExporter.ts     ModelExporter subclass — write-side
├── index.ts                  module re-exports
└── versions/1_0/
    ├── parse.ts                  fileData → SceneModel.fromParams
    └── encode.ts                 SceneModel.toParams → SceneModelParams
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