xeokit Scene AABB3 Index

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Utilities for computing and managing Axis-Aligned Bounding Boxes (AABB) in xeokit scenes.

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The Scene AABB3 Index provides fast, centralized access to bounding boxes for entire scenes, individual objects, and meshes. It keeps these bounds up to date as the scene changes, making it useful for view framing, spatial queries, and scene analysis.

Features

• Computes and maintains AABBs for Scene, SceneObject, and SceneMesh.
• Supports world-space AABB calculation for compressed geometry.
• Provides scene-wide bounds and center point calculations.
• Automatically updates in response to scene lifecycle events.

Installation

npm install @xeokit/sdk
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Usage

This section walks through creating a scene, populating it with geometry, and querying bounding boxes using the Scene AABB3 Index.

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Step 1: Import required modules

Import the Scene API, the AABB index helpers, and any constants needed to define geometry.

import { Scene } from "@xeokit/sdk/scene";
import { SceneAABB3Index, getSceneAABB3Index } from "@xeokit/sdk/aabb";
import { TrianglesPrimitive } from "@xeokit/sdk/constants";
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Step 2: Create a Scene and SceneModel

Create a new Scene, then create a SceneModel to hold geometry and objects.

const scene = new Scene();

const sceneModelResult = scene.createModel({
    id: "demoModel"
});

if (!sceneModelResult.ok) {
  console.error("Failed to create model:", sceneModelResult.error);
}

const sceneModel = sceneModelResult.value;
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Step 3: Define geometry and meshes

Create geometry, attach it to a mesh, and then reference that mesh from a SceneObject.

sceneModel.createGeometry({
  id: "boxGeometry",
  primitive: TrianglesPrimitive,
  positions: [...],
  indices: [...]
});

sceneModel.createMesh({
  id: "boxMesh",
  geometryId: "boxGeometry",
  color: [1.0, 0.0, 0.0]
});

sceneModel.createObject({
  id: "object1",
  meshIds: ["boxMesh"]
});
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Step 4: Create or retrieve the SceneAABB3Index

Obtain a SceneAABB3Index for the Scene. If one already exists, it will be reused automatically.

const sceneAABB3Index = getSceneAABB3Index(scene);
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Step 5: Query scene-level bounds

Retrieve the axis-aligned bounding box for the entire Scene, as well as its center point.

const sceneAABB = sceneAABB3Index.getSceneAABB();
console.log("Scene AABB:", sceneAABB);

const sceneCenter = sceneAABB3Index.getSceneCenter();
console.log("Scene Center:", sceneCenter);
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Step 6: Query object-level bounds

Get the AABB for a single SceneObject by ID.

const objectAABB = sceneAABB3Index.getObjectAABB("object1");
console.log("Object1 AABB:", objectAABB);
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You can also compute a combined bounding box for multiple objects.

const combinedAABB =
  sceneAABB3Index.getCombinedObjectAABB(["object1", "object2"]);

console.log("Combined AABB:", combinedAABB);
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Step 7: Clean up

When the index is no longer needed, destroy it explicitly. The index will also be destroyed automatically when the Scene itself is destroyed.

sceneAABB3Index.destroy();
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