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OrientedBoundingBox

An OrientedBoundingBox is a closed and convex cuboid. It can provide a tighter bounding volume than a bounding sphere or an axis aligned bounding box in many cases.

The class support two representations of an oriented bounding box:

Usage

Create an OrientedBoundingBox using a transformation matrix, a position where the box will be translated, and a scale.

import {Vector3} from '@math.gl/core';
import {OrientedBoundingBox} from '@math.gl/culling';

const center = new Vector3(1.0, 0.0, 0.0);
const halfAxes = new Matrix3().fromScale([1.0, 3.0, 2.0]);
const box = new OrientedBoundingBox(center, halfAxes);

Sort bounding boxes from back to front

boxes.sort(
  (boxA, boxB) =>
    boxB.distanceSquaredTo(camera.positionWC) - boxA.distanceSquaredTo(camera.positionWC)
);

Compute an oriented bounding box enclosing two points.

import {makeOrientedBoundingBoxFromPoints} from '@math.gl/culling';

const box = makeOrientedBoundingBoxFromPoints([
  [2, 0, 0],
  [-2, 0, 0]
]);

Inheritance​

class OrientedBoundingBox implements BoundingVolume.

Global Functions​

makeOrientedBoundingBoxFromPoints(positions : Array[3][], result? : OrientedBoundingBox) : OrientedBoundingBox​

Computes an instance of an OrientedBoundingBox of the given positions. This is an implementation of Stefan Gottschalk's Collision Queries using Oriented Bounding Boxes (PHD thesis).

  • positions List of Vector3 points that the bounding box will enclose.
  • result Optional object onto which to store the result.

Fields​

center: Vector3​

The center position of the box.

halfAxes: Matrix3​

The transformation matrix, to rotate the box to the right position.

readonly halfSize: number[]​

The array with three half-sizes for the bounding box

readonly quaternion: Quaternion​

The quaternion describing the orientation of the bounding box

Methods​

constructor(center = [0, 0, 0], halfAxes = [0, 0, 0, 0, 0, 0, 0, 0, 0]) {​

constructor​

  • center=Vector3.ZERO The center of the box.
  • halfAxes=Matrix3.ZERO The three orthogonal half-axes of the bounding box. Equivalently, the transformation matrix, to rotate and scale a cube centered at the origin.

fromCenterHalfSizeQuaternion(center : number[], halfSize : number[], quaternion : number[]) : OrientedBoundingBox​

Create an OrientedBoundingBox from a half-size-quaternion based OBB

clone() : OrientedBoundingBox​

Duplicates a OrientedBoundingBox instance.

Returns

  • A new OrientedBoundingBox instance.

equals(right: OrientedBoundingBox) : Boolean​

Compares the provided OrientedBoundingBox componentwise and returns true if they are equal, false otherwise.

  • right The second OrientedBoundingBox

Returns

  • true if left and right are equal, false otherwise.

intersectPlane(plane : Plane) : INTERSECTION​

Determines which side of a plane the oriented bounding box is located.

  • plane The plane to test against.

Returns

  • INTERSECTION.INSIDE if the entire box is on the side of the plane the normal is pointing
  • INTERSECTION.OUTSIDE if the entire box is on the opposite side, and
  • INTERSECTION.INTERSECTING if the box intersects the plane.

distanceTo(point : Number[3]) : Number​

Computes the estimated distance from the closest point on a bounding box to a point.

  • point The point

Returns

  • The estimated distance from the bounding sphere to the point.

distanceSquaredTo(point : Number[3]) : Number​

Computes the estimated distance squared from the closest point on a bounding box to a point.

  • point The point

Returns

  • The estimated distance squared from the bounding sphere to the point.

computePlaneDistances(position : Number[3], direction : Number[3], result : Number[2]]) : Number[2]​

The distances calculated by the vector from the center of the bounding box to position projected onto direction.

If you imagine the infinite number of planes with normal direction, this computes the smallest distance to the closest and farthest planes from position that intersect the bounding box.

  • position The position to calculate the distance from.
  • direction The direction from position.
  • result An optional Interval to store the nearest and farthest distances.

Returns

  • The nearest and farthest distances on the bounding box from position in direction.

Attribution​

This class was ported from Cesium under the Apache 2 License.