xeokit Legacy XKT Importer / Exporter

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Imports and exports xeokit's legacy XKT binary format.

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XKT is the native binary format of xeokit v2, produced by xeokit-convert. It has been superseded by XGF in v3, but is still supported for compatibility with existing XKT assets. XKTLoader reads the geometry, meshes, and objects into a SceneModel, and the embedded model / object metadata into a DataModel; XKTExporter writes a SceneModel + DataModel back out as XKT.

An XKT file pools all geometry into shared arrays of 16-bit quantised positions, indices, and per-mesh material attributes, grouped into spatial tiles. Geometry used by a single mesh is baked into its tile's coordinate frame; geometry shared by several meshes is instanced. The loader reconstructs this into SceneModel geometries, meshes (placed with a per-tile RTC origin for full precision), and objects, and maps the metadata metaObjects into a DataModel object tree with aggregation relationships.

Scope

• Loading: XKT versions 7 through 12. Versions 7-10 use the legacy zlib-deflated container; versions 11-12 use the uncompressed offset-table container emitted by current xeokit-convert. Versions 1-6 are not handled.
• Triangle (solid / surface), line, and point primitives.
• Per-mesh colour and opacity; metallic / roughness, textures, texture sets, and UVs are not applied.
• Metadata is mapped to a DataModel from version 8 onwards (v8 stores it as parallel arrays; v9+ as a JSON document); versions 7 and earlier carried metadata in a separate file.
• Export writes XKT version 12 only: a single tile and one geometry per mesh (geometry is not re-instanced) with no textures.

Usage

import {Scene} from "@xeokit/sdk/model/scene";
import {Data} from "@xeokit/sdk/model/data";
import {XKTLoader, XKTExporter} from "@xeokit/sdk/formats/xkt";

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

const fileData = await (await fetch("model.xkt")).arrayBuffer();
await new XKTLoader().load({fileData, sceneModel, dataModel});

// …and back out:
const xkt = await new XKTExporter().write({sceneModel, dataModel}); // ArrayBuffer
Copy

The loader's / exporter's fileDataType is "arraybuffer", so read the .xkt as an ArrayBuffer first, and the exporter resolves to one.