GLTFLoaderPlugin

Viewer plugin that loads models from glTF.

• Creates an Entity representing each model it loads, which will have Entity#isModel set true and will be registered by Entity#id in Scene#models.
• Creates an Entity for each object within the model, which is indicated by each glTF node that has a name attribute. Those Entities will have Entity#isObject set true and will be registered by Entity#id in Scene#objects.
• When loading, can set the World-space position, scale and rotation of each model within World space, along with initial properties for all the model's Entitys.

Metadata

GLTFLoaderPlugin can also load an accompanying JSON metadata file with each model, which creates a MetaModel corresponding to the model Entity and a MetaObject corresponding to each object Entity.

Each MetaObject has a MetaObject#type, which indicates the classification of its corresponding Entity. When loading metadata, we can also provide GLTFLoaderPlugin with a custom lookup table of initial values to set on the properties of each type of Entity. By default, GLTFLoaderPlugin uses its own map of default colors and visibilities for IFC element types.

Quality Setting

By default, GLTFLoaderPlugin will load a high-performance scene representation that's optimized for low memory usage and optimal rendering. The high-performance representation renders large numbers of objects efficiently, using geometry batching and instancing, with simple Lambertian shading that ignores any textures and realistic materials in the glTF.

Specifying performance:false to GLTFLoaderPlugin#load will internally load a heavier scene representation comprised of Node, Mesh, Geometry, Material and Texture components, that will exactly preserve the materials specified in the glTF. Use this when you want to load a model for a realistic preview, maybe using PBR etc.

We tend to use the default performance:true setting for CAD and BIM models, where structure is more important that surface appearance.

Publically, GLTFLoaderPlugin creates the same Entitys for both levels of performance. Privately, however, it implements Entitys using two different sets of concrete subtypes, for its two different internally-managed scene representations.

Usage

In the example below we'll load the Schependomlaan model from a glTF file, along with an accompanying JSON IFC metadata file.

This will create a bunch of Entitys that represents the model and its objects, along with a MetaModel and MetaObjects that hold their metadata.

Since this model contains IFC types, the GLTFLoaderPlugin will set the initial colors of object Entitys according to the standard IFC element colors in the GLTFModel's current map. Override that with your own map via property GLTFLoaderPlugin#objectDefaults.

Read more about this example in the user guide on Viewing BIM Models Offline.

We're leaving performance: true since our model has many objects and we're not interested in realistic rendering.

[Run this example]

import {Viewer, GLTFLoaderPlugin} from "xeokit-sdk.es.js";

//------------------------------------------------------------------------------------------------------------------
// 1. Create a Viewer,
// 2. Arrange the camera,
// 3. Tweak the selection material (tone it down a bit)
//------------------------------------------------------------------------------------------------------------------

// 1
const viewer = new Viewer({
     canvasId: "myCanvas",
     transparent: true
});

// 2
viewer.camera.orbitPitch(20);
viewer.camera.orbitYaw(-45);

// 3
viewer.scene.selectedMaterial.fillAlpha = 0.1;

//------------------------------------------------------------------------------------------------------------------
// 1. Create a glTF loader plugin,
// 2. Load a glTF building model and JSON IFC metadata
// 3. Emphasis the edges to make it look nice
//------------------------------------------------------------------------------------------------------------------

// 1
const gltfLoader = new GLTFLoaderPlugin(viewer);

// 2
var model = gltfLoader.load({                                    // Returns an Entity that represents the model
     id: "myModel",
     src: "./models/gltf/OTCConferenceCenter/scene.gltf",
     metaModelSrc: "./models/gltf/OTCConferenceCenter/metaModel.json",     // Creates a MetaModel (see below)
     edges: true,
     performance: true  // Load high-performance scene representation (default is false)
});

model.on("loaded", () => {

     //--------------------------------------------------------------------------------------------------------------
     // 1. Find metadata on the third storey
     // 2. Select all the objects in the building's third storey
     // 3. Fit the camera to all the objects on the third storey
     //--------------------------------------------------------------------------------------------------------------

     // 1
     const metaModel = viewer.metaScene.metaModels["myModel"];       // MetaModel with ID "myModel"
     const metaObject
         = viewer.metaScene.metaObjects["0u4wgLe6n0ABVaiXyikbkA"];   // MetaObject with ID "0u4wgLe6n0ABVaiXyikbkA"

     const name = metaObject.name;                                   // "01 eerste verdieping"
     const type = metaObject.type;                                   // "IfcBuildingStorey"
     const parent = metaObject.parent;                               // MetaObject with type "IfcBuilding"
     const children = metaObject.children;                           // Array of child MetaObjects
     const objectId = metaObject.id;                                 // "0u4wgLe6n0ABVaiXyikbkA"
     const objectIds = viewer.metaScene.getObjectIDsInSubtree(objectId);   // IDs of leaf sub-objects
     const aabb = viewer.scene.getAABB(objectIds);                   // Axis-aligned boundary of the leaf sub-objects

     // 2
     viewer.scene.setObjectsSelected(objectIds, true);

     // 3
     viewer.cameraFlight.flyTo(aabb);
});

// Find the model Entity by ID
model = viewer.scene.models["myModel"];

// Destroy the model
model.destroy();

Transforming

We have the option to rotate, scale and translate each .glTF model as we load it.

This lets us load multiple models, or even multiple copies of the same model, and position them apart from each other.

In the example below, we'll scale our model to half its size, rotate it 90 degrees about its local X-axis, then translate it 100 units along its X axis.

[Run example]

const model = gltfLoader.load({
     src: "./models/gltf/Duplex/scene.gltf",
     metaModelSrc: "./models/gltf/Duplex/Duplex.json",
     rotation: [90,0,0],
     scale: [0.5, 0.5, 0.5],
     position: [100, 0, 0]
});

Including and excluding IFC types

We can also load only those objects that have the specified IFC types. In the example below, we'll load only the objects that represent walls.

[Run this example]

const model = gltfLoader.load({
    id: "myModel",
     src: "./models/gltf/OTCConferenceCenter/scene.gltf",
     metaModelSrc: "./models/gltf/OTCConferenceCenter/metaModel.json",
     includeTypes: ["IfcWallStandardCase"]
});

We can also load only those objects that don't have the specified IFC types. In the example below, we'll load only the objects that do not represent empty space.

const model = gltfLoader.load({
    id: "myModel",
     src: "./models/gltf/OTCConferenceCenter/scene.gltf",
     metaModelSrc: "./models/gltf/OTCConferenceCenter/metaModel.json",
     excludeTypes: ["IfcSpace"]
});