xeokit 3D Collision Utilities

---

Efficient spatial searching and collision detection using 3D k-d trees, rays, and boundaries.

---

The KdTree3 provides a fast spatial search index that organizes 3D objects with axis-aligned boundaries, allowing efficient queries for intersections with other objects, volumes, and rays.

Features

This module includes functions for building and searching KdTree3 instances:

Building KdTree3s:

• createPrimsKdTree3 - Creates a KdTree3 containing primitives from geometry arrays, organized by their 3D boundaries.
• createSceneObjectPrimsKdTree3 - Creates a KdTree3 containing primitives from SceneObjects, organized by their world-space boundaries.
• createSceneObjectsKdTree3 - Creates a KdTree3 containing SceneObjects, organized by their world-space boundaries.

Searching KdTree3s:

• searchKdTree3WithAABB - Finds objects intersecting a given 3D axis-aligned bounding box (AABB).
• searchKdTree3WithFrustum - Finds objects intersecting a given 3D frustum volume.
• searchKdTree3WithRay - Finds objects intersecting a given 3D ray.

Use Cases

With these utilities, applications can implement:

• Frustum culling for SceneObjects
• Ray-picking for object selection
• Marquee selection of multiple objects

Installation

Install the xeokit SDK:

npm install @xeokit/sdk
Copy

Usage Example

Searching for SceneObjects intersecting a 3D world-space boundary:

import { Scene } from "@xeokit/sdk/scene";
import { SDKError } from "@xeokit/sdk/core";
import { TrianglesPrimitive } from "@xeokit/sdk/constants";
import { createSceneObjectsKdTree3, searchKdTree3WithAABB } from "@xeokit/sdk/kdtree3";

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

if (sceneModel instanceof SDKError) {
    console.error(sceneModel.message);
} else {
    sceneModel.createGeometry({
        id: "theGeometry",
        primitive: TrianglesPrimitive,
        positions: [10.07, 0, 11.07, 9.58, 3.11, 11.07, 8.15, ...],
        indices: [21, 0, 1, 1, 22, 21, 22, 1, 2, 2, 23, 22, 23, ...]
    });

    sceneModel.createLayerMesh({
        id: "tableTopMesh",
        geometryId: "theGeometry",
        position: [0, -3, 0],
        scale: [6, 0.5, 6],
        rotation: [0, 0, 0],
        color: [1.0, 0.3, 1.0]
    });

    sceneModel.createObject({
        id: "tableTopSceneObject",
        meshIds: ["tableTopMesh"]
    });

    sceneModel.build().then(() => {
        const kdTree = createSceneObjectsKdTree3(Object.values(scene.objects));

        const intersectingObjects = searchKdTree3WithAABB({
            kdTree,
            aabb: [0, 0, 0, 10, 10, 10]
        });

        console.log(intersectingObjects);
    });
}
Copy