Babylon.js/src/Culling/boundingSphere.ts

import { DeepImmutable } from "../types";
import { ArrayTools } from "../Misc/arrayTools";
import { Matrix, Vector3, Plane } from "../Maths/math";

/**
 * Class used to store bounding sphere information
 */
export class BoundingSphere {
    /**
     * Gets the center of the bounding sphere in local space
     */
    public readonly center = Vector3.Zero();
    /**
     * Radius of the bounding sphere in local space
     */
    public radius: number;
    /**
     * Gets the center of the bounding sphere in world space
     */
    public readonly centerWorld = Vector3.Zero();
    /**
     * Radius of the bounding sphere in world space
     */
    public radiusWorld: number;
    /**
     * Gets the minimum vector in local space
     */
    public readonly minimum = Vector3.Zero();
    /**
     * Gets the maximum vector in local space
     */
    public readonly maximum = Vector3.Zero();

    private _worldMatrix: DeepImmutable<Matrix>;
    private static readonly TmpVector3 = ArrayTools.BuildArray(3, Vector3.Zero);

    /**
     * Creates a new bounding sphere
     * @param min defines the minimum vector (in local space)
     * @param max defines the maximum vector (in local space)
     * @param worldMatrix defines the new world matrix
     */
    constructor(min: DeepImmutable<Vector3>, max: DeepImmutable<Vector3>, worldMatrix?: DeepImmutable<Matrix>) {
        this.reConstruct(min, max, worldMatrix);
    }

    /**
     * Recreates the entire bounding sphere from scratch as if we call the constructor in place
     * @param min defines the new minimum vector (in local space)
     * @param max defines the new maximum vector (in local space)
     * @param worldMatrix defines the new world matrix
     */
    public reConstruct(min: DeepImmutable<Vector3>, max: DeepImmutable<Vector3>, worldMatrix?: DeepImmutable<Matrix>) {
        this.minimum.copyFrom(min);
        this.maximum.copyFrom(max);

        var distance = Vector3.Distance(min, max);

        max.addToRef(min, this.center).scaleInPlace(0.5);
        this.radius = distance * 0.5;

        this._update(worldMatrix || Matrix.IdentityReadOnly);
    }

    /**
     * Scale the current bounding sphere by applying a scale factor
     * @param factor defines the scale factor to apply
     * @returns the current bounding box
     */
    public scale(factor: number): BoundingSphere {
        const newRadius = this.radius * factor;
        const tmpVectors = BoundingSphere.TmpVector3;
        const tempRadiusVector = tmpVectors[0].setAll(newRadius);
        const min = this.center.subtractToRef(tempRadiusVector, tmpVectors[1]);
        const max = this.center.addToRef(tempRadiusVector, tmpVectors[2]);

        this.reConstruct(min, max, this._worldMatrix);

        return this;
    }

    /**
     * Gets the world matrix of the bounding box
     * @returns a matrix
     */
    public getWorldMatrix(): DeepImmutable<Matrix> {
        return this._worldMatrix;
    }

    // Methods
    /** @hidden */
    public _update(worldMatrix: DeepImmutable<Matrix>): void {
        if (!worldMatrix.isIdentity()) {
            Vector3.TransformCoordinatesToRef(this.center, worldMatrix, this.centerWorld);
            const tempVector = BoundingSphere.TmpVector3[0];
            Vector3.TransformNormalFromFloatsToRef(1.0, 1.0, 1.0, worldMatrix, tempVector);
            this.radiusWorld = Math.max(Math.abs(tempVector.x), Math.abs(tempVector.y), Math.abs(tempVector.z)) * this.radius;
        }
        else {
            this.centerWorld.copyFrom(this.center);
            this.radiusWorld = this.radius;
        }
    }

    /**
     * Tests if the bounding sphere is intersecting the frustum planes
     * @param frustumPlanes defines the frustum planes to test
     * @returns true if there is an intersection
     */
    public isInFrustum(frustumPlanes: Array<DeepImmutable<Plane>>): boolean {
        let center = this.centerWorld;
        let radius = this.radiusWorld;
        for (let i = 0; i < 6; i++) {
            if (frustumPlanes[i].dotCoordinate(center) <= -radius) {
                return false;
            }
        }
        return true;
    }

    /**
     * Tests if the bounding sphere center is in between the frustum planes.
     * Used for optimistic fast inclusion.
     * @param frustumPlanes defines the frustum planes to test
     * @returns true if the sphere center is in between the frustum planes
     */
    public isCenterInFrustum(frustumPlanes: Array<DeepImmutable<Plane>>): boolean {
        let center = this.centerWorld;
        for (let i = 0; i < 6; i++) {
            if (frustumPlanes[i].dotCoordinate(center) < 0) {
                return false;
            }
        }
        return true;
    }

    /**
     * Tests if a point is inside the bounding sphere
     * @param point defines the point to test
     * @returns true if the point is inside the bounding sphere
     */
    public intersectsPoint(point: DeepImmutable<Vector3>): boolean {
        const squareDistance = Vector3.DistanceSquared(this.centerWorld, point);
        if (this.radiusWorld * this.radiusWorld < squareDistance) {
            return false;
        }

        return true;
    }

    // Statics
    /**
     * Checks if two sphere intersct
     * @param sphere0 sphere 0
     * @param sphere1 sphere 1
     * @returns true if the speres intersect
     */
    public static Intersects(sphere0: DeepImmutable<BoundingSphere>, sphere1: DeepImmutable<BoundingSphere>): boolean {
        const squareDistance = Vector3.DistanceSquared(sphere0.centerWorld, sphere1.centerWorld);
        const radiusSum = sphere0.radiusWorld + sphere1.radiusWorld;

        if (radiusSum * radiusSum < squareDistance) {
            return false;
        }

        return true;
    }
}